Move java,lua api and remaining plugins to src/

Change-Id: I1c3b87e886603678368428ae56a6bd3327cbc90d
Signed-off-by: Damjan Marion <damarion@cisco.com>

8 files changed, 6009 insertions, 0 deletions

diff --git a/src/plugins/snat/in2out.c b/src/plugins/snat/in2out.c
new file mode 100644
index 00000000000..c78fdd76631
--- /dev/null
+++ b/src/plugins/snat/in2out.c
@@ -0,0 +1,1597 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vlib/vlib.h>
+#include <vnet/vnet.h>
+#include <vnet/pg/pg.h>
+#include <vnet/handoff.h>
+
+#include <vnet/ip/ip.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/fib/ip4_fib.h>
+#include <snat/snat.h>
+
+#include <vppinfra/hash.h>
+#include <vppinfra/error.h>
+#include <vppinfra/elog.h>
+
+typedef struct {
+  u32 sw_if_index;
+  u32 next_index;
+  u32 session_index;
+  u32 is_slow_path;
+} snat_in2out_trace_t;
+
+typedef struct {
+  u32 next_worker_index;
+  u8 do_handoff;
+} snat_in2out_worker_handoff_trace_t;
+
+/* packet trace format function */
+static u8 * format_snat_in2out_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  snat_in2out_trace_t * t = va_arg (*args, snat_in2out_trace_t *);
+  char * tag;
+
+  tag = t->is_slow_path ? "SNAT_IN2OUT_SLOW_PATH" : "SNAT_IN2OUT_FAST_PATH";
+  
+  s = format (s, "%s: sw_if_index %d, next index %d, session %d", tag,
+              t->sw_if_index, t->next_index, t->session_index);
+
+  return s;
+}
+
+static u8 * format_snat_in2out_fast_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  snat_in2out_trace_t * t = va_arg (*args, snat_in2out_trace_t *);
+
+  s = format (s, "SANT_IN2OUT_FAST: sw_if_index %d, next index %d", 
+              t->sw_if_index, t->next_index);
+
+  return s;
+}
+
+static u8 * format_snat_in2out_worker_handoff_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  snat_in2out_worker_handoff_trace_t * t =
+    va_arg (*args, snat_in2out_worker_handoff_trace_t *);
+  char * m;
+
+  m = t->do_handoff ? "next worker" : "same worker";
+  s = format (s, "SNAT_IN2OUT_WORKER_HANDOFF: %s %d", m, t->next_worker_index);
+
+  return s;
+}
+
+vlib_node_registration_t snat_in2out_node;
+vlib_node_registration_t snat_in2out_slowpath_node;
+vlib_node_registration_t snat_in2out_fast_node;
+vlib_node_registration_t snat_in2out_worker_handoff_node;
+
+#define foreach_snat_in2out_error                       \
+_(UNSUPPORTED_PROTOCOL, "Unsupported protocol")         \
+_(IN2OUT_PACKETS, "Good in2out packets processed")      \
+_(OUT_OF_PORTS, "Out of ports")                         \
+_(BAD_OUTSIDE_FIB, "Outside VRF ID not found")          \
+_(BAD_ICMP_TYPE, "icmp type not echo-request")          \
+_(NO_TRANSLATION, "No translation")
+  
+typedef enum {
+#define _(sym,str) SNAT_IN2OUT_ERROR_##sym,
+  foreach_snat_in2out_error
+#undef _
+  SNAT_IN2OUT_N_ERROR,
+} snat_in2out_error_t;
+
+static char * snat_in2out_error_strings[] = {
+#define _(sym,string) string,
+  foreach_snat_in2out_error
+#undef _
+};
+
+typedef enum {
+  SNAT_IN2OUT_NEXT_LOOKUP,
+  SNAT_IN2OUT_NEXT_DROP,
+  SNAT_IN2OUT_NEXT_SLOW_PATH,
+  SNAT_IN2OUT_N_NEXT,
+} snat_in2out_next_t;
+
+static u32 slow_path (snat_main_t *sm, vlib_buffer_t *b0,
+                      ip4_header_t * ip0,
+                      u32 rx_fib_index0,
+                      snat_session_key_t * key0,
+                      snat_session_t ** sessionp,
+                      vlib_node_runtime_t * node,
+                      u32 next0,
+                      u32 cpu_index)
+{
+  snat_user_t *u;
+  snat_user_key_t user_key;
+  snat_session_t *s;
+  clib_bihash_kv_8_8_t kv0, value0;
+  u32 oldest_per_user_translation_list_index;
+  dlist_elt_t * oldest_per_user_translation_list_elt;
+  dlist_elt_t * per_user_translation_list_elt;
+  dlist_elt_t * per_user_list_head_elt;
+  u32 session_index;
+  snat_session_key_t key1;
+  u32 address_index = ~0;
+  u32 outside_fib_index;
+  uword * p;
+  snat_static_mapping_key_t worker_by_out_key;
+
+  p = hash_get (sm->ip4_main->fib_index_by_table_id, sm->outside_vrf_id);
+  if (! p)
+    {
+      b0->error = node->errors[SNAT_IN2OUT_ERROR_BAD_OUTSIDE_FIB];
+      return SNAT_IN2OUT_NEXT_DROP;
+    }
+  outside_fib_index = p[0];
+
+  user_key.addr = ip0->src_address;
+  user_key.fib_index = rx_fib_index0;
+  kv0.key = user_key.as_u64;
+  
+  /* Ever heard of the "user" = src ip4 address before? */
+  if (clib_bihash_search_8_8 (&sm->user_hash, &kv0, &value0))
+    {
+      /* no, make a new one */
+      pool_get (sm->per_thread_data[cpu_index].users, u);
+      memset (u, 0, sizeof (*u));
+      u->addr = ip0->src_address;
+
+      pool_get (sm->per_thread_data[cpu_index].list_pool, per_user_list_head_elt);
+
+      u->sessions_per_user_list_head_index = per_user_list_head_elt -
+        sm->per_thread_data[cpu_index].list_pool;
+
+      clib_dlist_init (sm->per_thread_data[cpu_index].list_pool,
+                       u->sessions_per_user_list_head_index);
+
+      kv0.value = u - sm->per_thread_data[cpu_index].users;
+
+      /* add user */
+      clib_bihash_add_del_8_8 (&sm->user_hash, &kv0, 1 /* is_add */);
+    }
+  else
+    {
+      u = pool_elt_at_index (sm->per_thread_data[cpu_index].users,
+                             value0.value);
+    }
+
+  /* Over quota? Recycle the least recently used dynamic translation */
+  if (u->nsessions >= sm->max_translations_per_user)
+    {
+      /* Remove the oldest dynamic translation */
+      do {
+          oldest_per_user_translation_list_index =
+            clib_dlist_remove_head (sm->per_thread_data[cpu_index].list_pool,
+                                    u->sessions_per_user_list_head_index);
+
+          ASSERT (oldest_per_user_translation_list_index != ~0);
+
+          /* add it back to the end of the LRU list */
+          clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                              u->sessions_per_user_list_head_index,
+                              oldest_per_user_translation_list_index);
+          /* Get the list element */
+          oldest_per_user_translation_list_elt =
+            pool_elt_at_index (sm->per_thread_data[cpu_index].list_pool,
+                               oldest_per_user_translation_list_index);
+
+          /* Get the session index from the list element */
+          session_index = oldest_per_user_translation_list_elt->value;
+
+          /* Get the session */
+          s = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
+                                 session_index);
+      } while (snat_is_session_static (s));
+
+      /* Remove in2out, out2in keys */
+      kv0.key = s->in2out.as_u64;
+      if (clib_bihash_add_del_8_8 (&sm->in2out, &kv0, 0 /* is_add */))
+          clib_warning ("in2out key delete failed");
+      kv0.key = s->out2in.as_u64;
+      if (clib_bihash_add_del_8_8 (&sm->out2in, &kv0, 0 /* is_add */))
+          clib_warning ("out2in key delete failed");
+
+      snat_free_outside_address_and_port 
+        (sm, &s->out2in, s->outside_address_index);
+      s->outside_address_index = ~0;
+
+      if (snat_alloc_outside_address_and_port (sm, &key1, &address_index))
+        {
+          ASSERT(0);
+
+          b0->error = node->errors[SNAT_IN2OUT_ERROR_OUT_OF_PORTS];
+          return SNAT_IN2OUT_NEXT_DROP;
+        }
+      s->outside_address_index = address_index;
+    }
+  else
+    {
+      u8 static_mapping = 1;
+
+      /* First try to match static mapping by local address and port */
+      if (snat_static_mapping_match (sm, *key0, &key1, 0))
+        {
+          static_mapping = 0;
+          /* Try to create dynamic translation */
+          if (snat_alloc_outside_address_and_port (sm, &key1, &address_index))
+            {
+              b0->error = node->errors[SNAT_IN2OUT_ERROR_OUT_OF_PORTS];
+              return SNAT_IN2OUT_NEXT_DROP;
+            }
+        }
+
+      /* Create a new session */
+      pool_get (sm->per_thread_data[cpu_index].sessions, s);
+      memset (s, 0, sizeof (*s));
+      
+      s->outside_address_index = address_index;
+
+      if (static_mapping)
+        {
+          u->nstaticsessions++;
+          s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
+        }
+      else
+        {
+          u->nsessions++;
+        }
+
+      /* Create list elts */
+      pool_get (sm->per_thread_data[cpu_index].list_pool,
+                per_user_translation_list_elt);
+      clib_dlist_init (sm->per_thread_data[cpu_index].list_pool,
+                       per_user_translation_list_elt -
+                       sm->per_thread_data[cpu_index].list_pool);
+
+      per_user_translation_list_elt->value =
+        s - sm->per_thread_data[cpu_index].sessions;
+      s->per_user_index = per_user_translation_list_elt -
+                          sm->per_thread_data[cpu_index].list_pool;
+      s->per_user_list_head_index = u->sessions_per_user_list_head_index;
+
+      clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                          s->per_user_list_head_index,
+                          per_user_translation_list_elt -
+                          sm->per_thread_data[cpu_index].list_pool);
+   }
+  
+  s->in2out = *key0;
+  s->out2in = key1;
+  s->out2in.protocol = key0->protocol;
+  s->out2in.fib_index = outside_fib_index;
+  *sessionp = s;
+
+  /* Add to translation hashes */
+  kv0.key = s->in2out.as_u64;
+  kv0.value = s - sm->per_thread_data[cpu_index].sessions;
+  if (clib_bihash_add_del_8_8 (&sm->in2out, &kv0, 1 /* is_add */))
+      clib_warning ("in2out key add failed");
+  
+  kv0.key = s->out2in.as_u64;
+  kv0.value = s - sm->per_thread_data[cpu_index].sessions;
+  
+  if (clib_bihash_add_del_8_8 (&sm->out2in, &kv0, 1 /* is_add */))
+      clib_warning ("out2in key add failed");
+
+  /* Add to translated packets worker lookup */
+  worker_by_out_key.addr = s->out2in.addr;
+  worker_by_out_key.port = s->out2in.port;
+  worker_by_out_key.fib_index = s->out2in.fib_index;
+  kv0.key = worker_by_out_key.as_u64;
+  kv0.value = cpu_index;
+  clib_bihash_add_del_8_8 (&sm->worker_by_out, &kv0, 1);
+  return next0;
+}
+                      
+static inline u32 icmp_in2out_slow_path (snat_main_t *sm,
+                                         vlib_buffer_t * b0,
+                                         ip4_header_t * ip0,
+                                         icmp46_header_t * icmp0,
+                                         u32 sw_if_index0,
+                                         u32 rx_fib_index0,
+                                         vlib_node_runtime_t * node,
+                                         u32 next0,
+                                         f64 now,
+                                         u32 cpu_index)
+{
+  snat_session_key_t key0;
+  icmp_echo_header_t *echo0;
+  clib_bihash_kv_8_8_t kv0, value0;
+  snat_session_t * s0;
+  u32 new_addr0, old_addr0;
+  u16 old_id0, new_id0;
+  ip_csum_t sum0;
+  snat_runtime_t * rt = (snat_runtime_t *)node->runtime_data;
+
+  if (PREDICT_FALSE(icmp0->type != ICMP4_echo_request))
+    {
+      b0->error = node->errors[SNAT_IN2OUT_ERROR_BAD_ICMP_TYPE];
+      return SNAT_IN2OUT_NEXT_DROP;
+    }
+  
+  echo0 = (icmp_echo_header_t *)(icmp0+1);
+
+  key0.addr = ip0->src_address;
+  key0.port = echo0->identifier;
+  key0.protocol = SNAT_PROTOCOL_ICMP;
+  key0.fib_index = rx_fib_index0;
+  
+  kv0.key = key0.as_u64;
+  
+  if (clib_bihash_search_8_8 (&sm->in2out, &kv0, &value0))
+    {
+      ip4_address_t * first_int_addr;
+
+      if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+        {
+          first_int_addr = 
+            ip4_interface_first_address (sm->ip4_main, sw_if_index0,
+                                         0 /* just want the address */);
+          rt->cached_sw_if_index = sw_if_index0;
+          rt->cached_ip4_address = first_int_addr->as_u32;
+        }
+      
+      /* Don't NAT packet aimed at the intfc address */
+      if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
+                                rt->cached_ip4_address))
+        return next0;
+      
+      next0 = slow_path (sm, b0, ip0, rx_fib_index0, &key0,
+                         &s0, node, next0, cpu_index);
+      
+      if (PREDICT_FALSE (next0 == SNAT_IN2OUT_NEXT_DROP))
+        return next0;
+    }
+  else
+    s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
+                            value0.value);
+
+  old_addr0 = ip0->src_address.as_u32;
+  ip0->src_address = s0->out2in.addr;
+  new_addr0 = ip0->src_address.as_u32;
+  vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->out2in.fib_index;
+  
+  sum0 = ip0->checksum;
+  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                         ip4_header_t,
+                         src_address /* changed member */);
+  ip0->checksum = ip_csum_fold (sum0);
+  
+  old_id0 = echo0->identifier;
+  new_id0 = s0->out2in.port;
+  echo0->identifier = new_id0;
+
+  sum0 = icmp0->checksum;
+  sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
+                         identifier);
+  icmp0->checksum = ip_csum_fold (sum0);
+
+  /* Accounting */
+  s0->last_heard = now;
+  s0->total_pkts++;
+  s0->total_bytes += vlib_buffer_length_in_chain (sm->vlib_main, b0);
+  /* Per-user LRU list maintenance for dynamic translations */
+  if (!snat_is_session_static (s0))
+    {
+      clib_dlist_remove (sm->per_thread_data[cpu_index].list_pool,
+                         s0->per_user_index);
+      clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                          s0->per_user_list_head_index,
+                          s0->per_user_index);
+    }
+
+  return next0;
+}
+
+/**
+ * @brief Hairpinning
+ *
+ * Hairpinning allows two endpoints on the internal side of the NAT to
+ * communicate even if they only use each other's external IP addresses
+ * and ports.
+ *
+ * @param sm     SNAT main.
+ * @param b0     Vlib buffer.
+ * @param ip0    IP header.
+ * @param udp0   UDP header.
+ * @param tcp0   TCP header.
+ * @param proto0 SNAT protocol.
+ */
+static inline void
+snat_hairpinning (snat_main_t *sm,
+                  vlib_buffer_t * b0,
+                  ip4_header_t * ip0,
+                  udp_header_t * udp0,
+                  tcp_header_t * tcp0,
+                  u32 proto0)
+{
+  snat_session_key_t key0, sm0;
+  snat_static_mapping_key_t k0;
+  snat_session_t * s0;
+  clib_bihash_kv_8_8_t kv0, value0;
+  ip_csum_t sum0;
+  u32 new_dst_addr0 = 0, old_dst_addr0, ti = 0, si;
+  u16 new_dst_port0, old_dst_port0;
+
+  key0.addr = ip0->dst_address;
+  key0.port = udp0->dst_port;
+  key0.protocol = proto0;
+  key0.fib_index = sm->outside_fib_index;
+  kv0.key = key0.as_u64;
+
+  /* Check if destination is in active sessions */
+  if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
+    {
+      /* or static mappings */
+      if (!snat_static_mapping_match(sm, key0, &sm0, 1))
+        {
+          new_dst_addr0 = sm0.addr.as_u32;
+          new_dst_port0 = sm0.port;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
+        }
+    }
+  else
+    {
+      si = value0.value;
+      if (sm->num_workers > 1)
+        {
+          k0.addr = ip0->dst_address;
+          k0.port = udp0->dst_port;
+          k0.fib_index = sm->outside_fib_index;
+          kv0.key = k0.as_u64;
+          if (clib_bihash_search_8_8 (&sm->worker_by_out, &kv0, &value0))
+            ASSERT(0);
+          else
+            ti = value0.value;
+        }
+      else
+        ti = sm->num_workers;
+
+      s0 = pool_elt_at_index (sm->per_thread_data[ti].sessions, si);
+      new_dst_addr0 = s0->in2out.addr.as_u32;
+      new_dst_port0 = s0->in2out.port;
+      vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
+    }
+
+  /* Destination is behind the same NAT, use internal address and port */
+  if (new_dst_addr0)
+    {
+      old_dst_addr0 = ip0->dst_address.as_u32;
+      ip0->dst_address.as_u32 = new_dst_addr0;
+      sum0 = ip0->checksum;
+      sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0,
+                             ip4_header_t, dst_address);
+      ip0->checksum = ip_csum_fold (sum0);
+
+      old_dst_port0 = tcp0->ports.dst;
+      if (PREDICT_TRUE(new_dst_port0 != old_dst_port0))
+        {
+          if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+            {
+              tcp0->ports.dst = new_dst_port0;
+              sum0 = tcp0->checksum;
+              sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0,
+                                     ip4_header_t, dst_address);
+              sum0 = ip_csum_update (sum0, old_dst_port0, new_dst_port0,
+                                     ip4_header_t /* cheat */, length);
+              tcp0->checksum = ip_csum_fold(sum0);
+            }
+          else
+            {
+              udp0->dst_port = new_dst_port0;
+              udp0->checksum = 0;
+            }
+        }
+    }
+}
+
+static inline uword
+snat_in2out_node_fn_inline (vlib_main_t * vm,
+                            vlib_node_runtime_t * node,
+                            vlib_frame_t * frame, int is_slow_path)
+{
+  u32 n_left_from, * from, * to_next;
+  snat_in2out_next_t next_index;
+  u32 pkts_processed = 0;
+  snat_main_t * sm = &snat_main;
+  snat_runtime_t * rt = (snat_runtime_t *)node->runtime_data;
+  f64 now = vlib_time_now (vm);
+  u32 stats_node_index;
+  u32 cpu_index = os_get_cpu_number ();
+
+  stats_node_index = is_slow_path ? snat_in2out_slowpath_node.index :
+    snat_in2out_node.index;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
+
+      vlib_get_next_frame (vm, node, next_index,
+			   to_next, n_left_to_next);
+
+      while (n_left_from >= 4 && n_left_to_next >= 2)
+	{
+          u32 bi0, bi1;
+	  vlib_buffer_t * b0, * b1;
+          u32 next0, next1;
+          u32 sw_if_index0, sw_if_index1;
+          ip4_header_t * ip0, * ip1;
+          ip_csum_t sum0, sum1;
+          u32 new_addr0, old_addr0, new_addr1, old_addr1;
+          u16 old_port0, new_port0, old_port1, new_port1;
+          udp_header_t * udp0, * udp1;
+          tcp_header_t * tcp0, * tcp1;
+          icmp46_header_t * icmp0, * icmp1;
+          snat_session_key_t key0, key1;
+          u32 rx_fib_index0, rx_fib_index1;
+          u32 proto0, proto1;
+          snat_session_t * s0 = 0, * s1 = 0;
+          clib_bihash_kv_8_8_t kv0, value0, kv1, value1;
+          
+	  /* Prefetch next iteration. */
+	  {
+	    vlib_buffer_t * p2, * p3;
+            
+	    p2 = vlib_get_buffer (vm, from[2]);
+	    p3 = vlib_get_buffer (vm, from[3]);
+            
+	    vlib_prefetch_buffer_header (p2, LOAD);
+	    vlib_prefetch_buffer_header (p3, LOAD);
+
+	    CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
+	    CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
+	  }
+
+          /* speculatively enqueue b0 and b1 to the current next frame */
+	  to_next[0] = bi0 = from[0];
+	  to_next[1] = bi1 = from[1];
+	  from += 2;
+	  to_next += 2;
+	  n_left_from -= 2;
+	  n_left_to_next -= 2;
+          
+	  b0 = vlib_get_buffer (vm, bi0);
+	  b1 = vlib_get_buffer (vm, bi1);
+
+          ip0 = vlib_buffer_get_current (b0);
+          udp0 = ip4_next_header (ip0);
+          tcp0 = (tcp_header_t *) udp0;
+          icmp0 = (icmp46_header_t *) udp0;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+	  rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index, 
+                                   sw_if_index0);
+
+          next0 = next1 = SNAT_IN2OUT_NEXT_LOOKUP;
+
+          proto0 = ~0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_UDP) 
+            ? SNAT_PROTOCOL_UDP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_TCP) 
+            ? SNAT_PROTOCOL_TCP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_ICMP) 
+            ? SNAT_PROTOCOL_ICMP : proto0;
+
+          /* Next configured feature, probably ip4-lookup */
+          if (is_slow_path)
+            {
+              if (PREDICT_FALSE (proto0 == ~0))
+                goto trace00;
+              
+              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+                {
+                  next0 = icmp_in2out_slow_path 
+                    (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, 
+                     node, next0, now, cpu_index);
+                  goto trace00;
+                }
+            }
+          else
+            {
+              if (PREDICT_FALSE (proto0 == ~0 || proto0 == SNAT_PROTOCOL_ICMP))
+                {
+                  next0 = SNAT_IN2OUT_NEXT_SLOW_PATH;
+                  goto trace00;
+                }
+            }
+
+          key0.addr = ip0->src_address;
+          key0.port = udp0->src_port;
+          key0.protocol = proto0;
+          key0.fib_index = rx_fib_index0;
+          
+          kv0.key = key0.as_u64;
+
+          if (PREDICT_FALSE (clib_bihash_search_8_8 (&sm->in2out, &kv0, &value0) != 0))
+            {
+              if (is_slow_path)
+                {
+                  ip4_address_t * first_int_addr;
+                  
+                  if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+                    {
+                      first_int_addr = 
+                        ip4_interface_first_address (sm->ip4_main, sw_if_index0,
+                                                     0 /* just want the address */);
+                      rt->cached_sw_if_index = sw_if_index0;
+                      rt->cached_ip4_address = first_int_addr->as_u32;
+                    }
+                  
+                  /* Don't NAT packet aimed at the intfc address */
+                  if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
+                                    rt->cached_ip4_address))
+                    goto trace00;
+                  
+                  next0 = slow_path (sm, b0, ip0, rx_fib_index0, &key0,
+                                     &s0, node, next0, cpu_index);
+                  if (PREDICT_FALSE (next0 == SNAT_IN2OUT_NEXT_DROP))
+                    goto trace00;
+                }
+              else
+                {
+                  next0 = SNAT_IN2OUT_NEXT_SLOW_PATH;
+                  goto trace00;
+                }
+            }
+          else
+            s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
+                                    value0.value);
+
+          old_addr0 = ip0->src_address.as_u32;
+          ip0->src_address = s0->out2in.addr;
+          new_addr0 = ip0->src_address.as_u32;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->out2in.fib_index;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                 ip4_header_t,
+                                 src_address /* changed member */);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+            {
+              old_port0 = tcp0->ports.src;
+              tcp0->ports.src = s0->out2in.port;
+              new_port0 = tcp0->ports.src;
+
+              sum0 = tcp0->checksum;
+              sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                     ip4_header_t,
+                                     dst_address /* changed member */);
+              sum0 = ip_csum_update (sum0, old_port0, new_port0,
+                                     ip4_header_t /* cheat */,
+                                     length /* changed member */);
+              tcp0->checksum = ip_csum_fold(sum0);
+            }
+          else
+            {
+              old_port0 = udp0->src_port;
+              udp0->src_port = s0->out2in.port;
+              udp0->checksum = 0;
+            }
+
+          /* Hairpinning */
+          snat_hairpinning (sm, b0, ip0, udp0, tcp0, proto0);
+
+          /* Accounting */
+          s0->last_heard = now;
+          s0->total_pkts++;
+          s0->total_bytes += vlib_buffer_length_in_chain (vm, b0);
+          /* Per-user LRU list maintenance for dynamic translation */
+          if (!snat_is_session_static (s0))
+            {
+              clib_dlist_remove (sm->per_thread_data[cpu_index].list_pool,
+                                 s0->per_user_index);
+              clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                                  s0->per_user_list_head_index,
+                                  s0->per_user_index);
+            }
+        trace00:
+
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED))) 
+            {
+              snat_in2out_trace_t *t = 
+                 vlib_add_trace (vm, node, b0, sizeof (*t));
+              t->is_slow_path = is_slow_path;
+              t->sw_if_index = sw_if_index0;
+              t->next_index = next0;
+                  t->session_index = ~0;
+              if (s0)
+                t->session_index = s0 - sm->per_thread_data[cpu_index].sessions;
+            }
+
+          pkts_processed += next0 != SNAT_IN2OUT_NEXT_DROP;
+
+          ip1 = vlib_buffer_get_current (b1);
+          udp1 = ip4_next_header (ip1);
+          tcp1 = (tcp_header_t *) udp1;
+          icmp1 = (icmp46_header_t *) udp1;
+
+          sw_if_index1 = vnet_buffer(b1)->sw_if_index[VLIB_RX];
+	  rx_fib_index1 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index, 
+                                   sw_if_index1);
+
+          proto1 = ~0;
+          proto1 = (ip1->protocol == IP_PROTOCOL_UDP) 
+            ? SNAT_PROTOCOL_UDP : proto1;
+          proto1 = (ip1->protocol == IP_PROTOCOL_TCP) 
+            ? SNAT_PROTOCOL_TCP : proto1;
+          proto1 = (ip1->protocol == IP_PROTOCOL_ICMP) 
+            ? SNAT_PROTOCOL_ICMP : proto1;
+
+          /* Next configured feature, probably ip4-lookup */
+          if (is_slow_path)
+            {
+              if (PREDICT_FALSE (proto1 == ~0))
+                goto trace01;
+              
+              if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
+                {
+                  next1 = icmp_in2out_slow_path 
+                    (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node,
+                     next1, now, cpu_index);
+                  goto trace01;
+                }
+            }
+          else
+            {
+              if (PREDICT_FALSE (proto1 == ~0 || proto1 == SNAT_PROTOCOL_ICMP))
+                {
+                  next1 = SNAT_IN2OUT_NEXT_SLOW_PATH;
+                  goto trace01;
+                }
+            }
+
+          key1.addr = ip1->src_address;
+          key1.port = udp1->src_port;
+          key1.protocol = proto1;
+          key1.fib_index = rx_fib_index1;
+          
+          kv1.key = key1.as_u64;
+
+            if (PREDICT_FALSE(clib_bihash_search_8_8 (&sm->in2out, &kv1, &value1) != 0))
+            {
+              if (is_slow_path)
+                {
+                  ip4_address_t * first_int_addr;
+                  
+                  if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index1))
+                    {
+                      first_int_addr = 
+                        ip4_interface_first_address (sm->ip4_main, sw_if_index1,
+                                                     0 /* just want the address */);
+                      rt->cached_sw_if_index = sw_if_index1;
+                      rt->cached_ip4_address = first_int_addr->as_u32;
+                    }
+                  
+                  /* Don't NAT packet aimed at the intfc address */
+                  if (PREDICT_FALSE(ip1->dst_address.as_u32 ==
+                                    rt->cached_ip4_address))
+                    goto trace01;
+                  
+                  next1 = slow_path (sm, b1, ip1, rx_fib_index1, &key1,
+                                     &s1, node, next1, cpu_index);
+                  if (PREDICT_FALSE (next1 == SNAT_IN2OUT_NEXT_DROP))
+                    goto trace01;
+                }
+              else
+                {
+                  next1 = SNAT_IN2OUT_NEXT_SLOW_PATH;
+                  goto trace01;
+                }
+            }
+          else
+            s1 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
+                                    value1.value);
+
+          old_addr1 = ip1->src_address.as_u32;
+          ip1->src_address = s1->out2in.addr;
+          new_addr1 = ip1->src_address.as_u32;
+          vnet_buffer(b1)->sw_if_index[VLIB_TX] = s1->out2in.fib_index;
+
+          sum1 = ip1->checksum;
+          sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
+                                 ip4_header_t,
+                                 src_address /* changed member */);
+          ip1->checksum = ip_csum_fold (sum1);
+
+          if (PREDICT_TRUE(proto1 == SNAT_PROTOCOL_TCP))
+            {
+              old_port1 = tcp1->ports.src;
+              tcp1->ports.src = s1->out2in.port;
+              new_port1 = tcp1->ports.src;
+
+              sum1 = tcp1->checksum;
+              sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
+                                     ip4_header_t,
+                                     dst_address /* changed member */);
+              sum1 = ip_csum_update (sum1, old_port1, new_port1,
+                                     ip4_header_t /* cheat */,
+                                     length /* changed member */);
+              tcp1->checksum = ip_csum_fold(sum1);
+            }
+          else
+            {
+              old_port1 = udp1->src_port;
+              udp1->src_port = s1->out2in.port;
+              udp1->checksum = 0;
+            }
+
+          /* Hairpinning */
+          snat_hairpinning (sm, b1, ip1, udp1, tcp1, proto1);
+
+          /* Accounting */
+          s1->last_heard = now;
+          s1->total_pkts++;
+          s1->total_bytes += vlib_buffer_length_in_chain (vm, b1);
+          /* Per-user LRU list maintenance for dynamic translation */
+          if (!snat_is_session_static (s1))
+            {
+              clib_dlist_remove (sm->per_thread_data[cpu_index].list_pool,
+                                 s1->per_user_index);
+              clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                                  s1->per_user_list_head_index,
+                                  s1->per_user_index);
+            }
+        trace01:
+
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
+                            && (b1->flags & VLIB_BUFFER_IS_TRACED))) 
+            {
+              snat_in2out_trace_t *t = 
+                 vlib_add_trace (vm, node, b1, sizeof (*t));
+              t->sw_if_index = sw_if_index1;
+              t->next_index = next1;
+              t->session_index = ~0;
+              if (s1)
+                t->session_index = s1 - sm->per_thread_data[cpu_index].sessions;
+            }
+
+          pkts_processed += next1 != SNAT_IN2OUT_NEXT_DROP;
+
+          /* verify speculative enqueues, maybe switch current next frame */
+          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
+                                           to_next, n_left_to_next,
+                                           bi0, bi1, next0, next1);
+        }
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+          u32 bi0;
+	  vlib_buffer_t * b0;
+          u32 next0;
+          u32 sw_if_index0;
+          ip4_header_t * ip0;
+          ip_csum_t sum0;
+          u32 new_addr0, old_addr0;
+          u16 old_port0, new_port0;
+          udp_header_t * udp0;
+          tcp_header_t * tcp0;
+          icmp46_header_t * icmp0;
+          snat_session_key_t key0;
+          u32 rx_fib_index0;
+          u32 proto0;
+          snat_session_t * s0 = 0;
+          clib_bihash_kv_8_8_t kv0, value0;
+          
+          /* speculatively enqueue b0 to the current next frame */
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+          next0 = SNAT_IN2OUT_NEXT_LOOKUP;
+
+          ip0 = vlib_buffer_get_current (b0);
+          udp0 = ip4_next_header (ip0);
+          tcp0 = (tcp_header_t *) udp0;
+          icmp0 = (icmp46_header_t *) udp0;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+	  rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index, 
+                                   sw_if_index0);
+
+          proto0 = ~0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_UDP) 
+            ? SNAT_PROTOCOL_UDP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_TCP) 
+            ? SNAT_PROTOCOL_TCP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_ICMP) 
+            ? SNAT_PROTOCOL_ICMP : proto0;
+
+          /* Next configured feature, probably ip4-lookup */
+          if (is_slow_path)
+            {
+              if (PREDICT_FALSE (proto0 == ~0))
+                goto trace0;
+              
+              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+                {
+                  next0 = icmp_in2out_slow_path 
+                    (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
+                     next0, now, cpu_index);
+                  goto trace0;
+                }
+            }
+          else
+            {
+              if (PREDICT_FALSE (proto0 == ~0 || proto0 == SNAT_PROTOCOL_ICMP))
+                {
+                  next0 = SNAT_IN2OUT_NEXT_SLOW_PATH;
+                  goto trace0;
+                }
+            }
+
+          key0.addr = ip0->src_address;
+          key0.port = udp0->src_port;
+          key0.protocol = proto0;
+          key0.fib_index = rx_fib_index0;
+          
+          kv0.key = key0.as_u64;
+
+          if (clib_bihash_search_8_8 (&sm->in2out, &kv0, &value0))
+            {
+              if (is_slow_path)
+                {
+                  ip4_address_t * first_int_addr;
+                  
+                  if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+                    {
+                      first_int_addr = 
+                        ip4_interface_first_address (sm->ip4_main, sw_if_index0,
+                                                     0 /* just want the address */);
+                      rt->cached_sw_if_index = sw_if_index0;
+                      rt->cached_ip4_address = first_int_addr->as_u32;
+                    }
+                  
+                  /* Don't NAT packet aimed at the intfc address */
+                  if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
+                                    rt->cached_ip4_address))
+                    goto trace0;
+                  
+                  next0 = slow_path (sm, b0, ip0, rx_fib_index0, &key0,
+                                     &s0, node, next0, cpu_index);
+                  if (PREDICT_FALSE (next0 == SNAT_IN2OUT_NEXT_DROP))
+                    goto trace0;
+                }
+              else
+                {
+                  next0 = SNAT_IN2OUT_NEXT_SLOW_PATH;
+                  goto trace0;
+                }
+            }
+          else
+            s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
+                                    value0.value);
+
+          old_addr0 = ip0->src_address.as_u32;
+          ip0->src_address = s0->out2in.addr;
+          new_addr0 = ip0->src_address.as_u32;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->out2in.fib_index;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                 ip4_header_t,
+                                 src_address /* changed member */);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+            {
+              old_port0 = tcp0->ports.src;
+              tcp0->ports.src = s0->out2in.port;
+              new_port0 = tcp0->ports.src;
+
+              sum0 = tcp0->checksum;
+              sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                     ip4_header_t,
+                                     dst_address /* changed member */);
+              sum0 = ip_csum_update (sum0, old_port0, new_port0,
+                                     ip4_header_t /* cheat */,
+                                     length /* changed member */);
+              tcp0->checksum = ip_csum_fold(sum0);
+            }
+          else
+            {
+              old_port0 = udp0->src_port;
+              udp0->src_port = s0->out2in.port;
+              udp0->checksum = 0;
+            }
+
+          /* Hairpinning */
+          snat_hairpinning (sm, b0, ip0, udp0, tcp0, proto0);
+
+          /* Accounting */
+          s0->last_heard = now;
+          s0->total_pkts++;
+          s0->total_bytes += vlib_buffer_length_in_chain (vm, b0);
+          /* Per-user LRU list maintenance for dynamic translation */
+          if (!snat_is_session_static (s0))
+            {
+              clib_dlist_remove (sm->per_thread_data[cpu_index].list_pool,
+                                 s0->per_user_index);
+              clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                                  s0->per_user_list_head_index,
+                                  s0->per_user_index);
+            }
+
+        trace0:
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED))) 
+            {
+              snat_in2out_trace_t *t = 
+                 vlib_add_trace (vm, node, b0, sizeof (*t));
+              t->is_slow_path = is_slow_path;
+              t->sw_if_index = sw_if_index0;
+              t->next_index = next0;
+                  t->session_index = ~0;
+              if (s0)
+                t->session_index = s0 - sm->per_thread_data[cpu_index].sessions;
+            }
+
+          pkts_processed += next0 != SNAT_IN2OUT_NEXT_DROP;
+
+          /* verify speculative enqueue, maybe switch current next frame */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_node_increment_counter (vm, stats_node_index, 
+                               SNAT_IN2OUT_ERROR_IN2OUT_PACKETS, 
+                               pkts_processed);
+  return frame->n_vectors;
+}
+
+static uword
+snat_in2out_fast_path_fn (vlib_main_t * vm,
+                          vlib_node_runtime_t * node,
+                          vlib_frame_t * frame)
+{
+  return snat_in2out_node_fn_inline (vm, node, frame, 0 /* is_slow_path */);
+}
+
+VLIB_REGISTER_NODE (snat_in2out_node) = {
+  .function = snat_in2out_fast_path_fn,
+  .name = "snat-in2out",
+  .vector_size = sizeof (u32),
+  .format_trace = format_snat_in2out_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  
+  .n_errors = ARRAY_LEN(snat_in2out_error_strings),
+  .error_strings = snat_in2out_error_strings,
+
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+  
+  .n_next_nodes = SNAT_IN2OUT_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [SNAT_IN2OUT_NEXT_DROP] = "error-drop",
+    [SNAT_IN2OUT_NEXT_LOOKUP] = "ip4-lookup",
+    [SNAT_IN2OUT_NEXT_SLOW_PATH] = "snat-in2out-slowpath",
+  },
+};
+
+VLIB_NODE_FUNCTION_MULTIARCH (snat_in2out_node, snat_in2out_fast_path_fn);
+
+static uword
+snat_in2out_slow_path_fn (vlib_main_t * vm,
+                          vlib_node_runtime_t * node,
+                          vlib_frame_t * frame)
+{
+  return snat_in2out_node_fn_inline (vm, node, frame, 1 /* is_slow_path */);
+}
+
+VLIB_REGISTER_NODE (snat_in2out_slowpath_node) = {
+  .function = snat_in2out_slow_path_fn,
+  .name = "snat-in2out-slowpath",
+  .vector_size = sizeof (u32),
+  .format_trace = format_snat_in2out_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  
+  .n_errors = ARRAY_LEN(snat_in2out_error_strings),
+  .error_strings = snat_in2out_error_strings,
+
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+  
+  .n_next_nodes = SNAT_IN2OUT_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [SNAT_IN2OUT_NEXT_DROP] = "error-drop",
+    [SNAT_IN2OUT_NEXT_LOOKUP] = "ip4-lookup",
+    [SNAT_IN2OUT_NEXT_SLOW_PATH] = "snat-in2out-slowpath",
+  },
+};
+
+VLIB_NODE_FUNCTION_MULTIARCH (snat_in2out_slowpath_node, snat_in2out_slow_path_fn);
+
+static uword
+snat_in2out_worker_handoff_fn (vlib_main_t * vm,
+                               vlib_node_runtime_t * node,
+                               vlib_frame_t * frame)
+{
+  snat_main_t *sm = &snat_main;
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+  u32 n_left_from, *from, *to_next = 0;
+  static __thread vlib_frame_queue_elt_t **handoff_queue_elt_by_worker_index;
+  static __thread vlib_frame_queue_t **congested_handoff_queue_by_worker_index
+    = 0;
+  vlib_frame_queue_elt_t *hf = 0;
+  vlib_frame_t *f = 0;
+  int i;
+  u32 n_left_to_next_worker = 0, *to_next_worker = 0;
+  u32 next_worker_index = 0;
+  u32 current_worker_index = ~0;
+  u32 cpu_index = os_get_cpu_number ();
+
+  ASSERT (vec_len (sm->workers));
+
+  if (PREDICT_FALSE (handoff_queue_elt_by_worker_index == 0))
+    {
+      vec_validate (handoff_queue_elt_by_worker_index, tm->n_vlib_mains - 1);
+
+      vec_validate_init_empty (congested_handoff_queue_by_worker_index,
+			       sm->first_worker_index + sm->num_workers - 1,
+			       (vlib_frame_queue_t *) (~0));
+    }
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+
+  while (n_left_from > 0)
+    {
+      u32 bi0;
+      vlib_buffer_t *b0;
+      u32 sw_if_index0;
+      u32 rx_fib_index0;
+      ip4_header_t * ip0;
+      snat_user_key_t key0;
+      clib_bihash_kv_8_8_t kv0, value0;
+      u8 do_handoff;
+
+      bi0 = from[0];
+      from += 1;
+      n_left_from -= 1;
+
+      b0 = vlib_get_buffer (vm, bi0);
+
+      sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+      rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index0);
+
+      ip0 = vlib_buffer_get_current (b0);
+
+      key0.addr = ip0->src_address;
+      key0.fib_index = rx_fib_index0;
+
+      kv0.key = key0.as_u64;
+
+      /* Ever heard of of the "user" before? */
+      if (clib_bihash_search_8_8 (&sm->worker_by_in, &kv0, &value0))
+        {
+          /* No, assign next available worker (RR) */
+          next_worker_index = sm->first_worker_index +
+            sm->workers[sm->next_worker++ % vec_len (sm->workers)];
+
+          /* add non-traslated packets worker lookup */
+          kv0.value = next_worker_index;
+          clib_bihash_add_del_8_8 (&sm->worker_by_in, &kv0, 1);
+        }
+      else
+        next_worker_index = value0.value;
+
+      if (PREDICT_FALSE (next_worker_index != cpu_index))
+        {
+          do_handoff = 1;
+
+          if (next_worker_index != current_worker_index)
+            {
+              if (hf)
+                hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;
+
+              hf = vlib_get_worker_handoff_queue_elt (sm->fq_in2out_index,
+                                                      next_worker_index,
+                                                      handoff_queue_elt_by_worker_index);
+
+              n_left_to_next_worker = VLIB_FRAME_SIZE - hf->n_vectors;
+              to_next_worker = &hf->buffer_index[hf->n_vectors];
+              current_worker_index = next_worker_index;
+            }
+
+          /* enqueue to correct worker thread */
+          to_next_worker[0] = bi0;
+          to_next_worker++;
+          n_left_to_next_worker--;
+
+          if (n_left_to_next_worker == 0)
+            {
+              hf->n_vectors = VLIB_FRAME_SIZE;
+              vlib_put_frame_queue_elt (hf);
+              current_worker_index = ~0;
+              handoff_queue_elt_by_worker_index[next_worker_index] = 0;
+              hf = 0;
+            }
+        }
+      else
+        {
+          do_handoff = 0;
+          /* if this is 1st frame */
+          if (!f)
+            {
+              f = vlib_get_frame_to_node (vm, snat_in2out_node.index);
+              to_next = vlib_frame_vector_args (f);
+            }
+
+          to_next[0] = bi0;
+          to_next += 1;
+          f->n_vectors++;
+        }
+
+      if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+			 && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+	{
+          snat_in2out_worker_handoff_trace_t *t =
+            vlib_add_trace (vm, node, b0, sizeof (*t));
+          t->next_worker_index = next_worker_index;
+          t->do_handoff = do_handoff;
+        }
+    }
+
+  if (f)
+    vlib_put_frame_to_node (vm, snat_in2out_node.index, f);
+
+  if (hf)
+    hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;
+
+  /* Ship frames to the worker nodes */
+  for (i = 0; i < vec_len (handoff_queue_elt_by_worker_index); i++)
+    {
+      if (handoff_queue_elt_by_worker_index[i])
+	{
+	  hf = handoff_queue_elt_by_worker_index[i];
+	  /*
+	   * It works better to let the handoff node
+	   * rate-adapt, always ship the handoff queue element.
+	   */
+	  if (1 || hf->n_vectors == hf->last_n_vectors)
+	    {
+	      vlib_put_frame_queue_elt (hf);
+	      handoff_queue_elt_by_worker_index[i] = 0;
+	    }
+	  else
+	    hf->last_n_vectors = hf->n_vectors;
+	}
+      congested_handoff_queue_by_worker_index[i] =
+	(vlib_frame_queue_t *) (~0);
+    }
+  hf = 0;
+  current_worker_index = ~0;
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (snat_in2out_worker_handoff_node) = {
+  .function = snat_in2out_worker_handoff_fn,
+  .name = "snat-in2out-worker-handoff",
+  .vector_size = sizeof (u32),
+  .format_trace = format_snat_in2out_worker_handoff_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  
+  .n_next_nodes = 1,
+
+  .next_nodes = {
+    [0] = "error-drop",
+  },
+};
+
+VLIB_NODE_FUNCTION_MULTIARCH (snat_in2out_worker_handoff_node, snat_in2out_worker_handoff_fn);
+
+static inline u32 icmp_in2out_static_map (snat_main_t *sm,
+                                          vlib_buffer_t * b0,
+                                          ip4_header_t * ip0,
+                                          icmp46_header_t * icmp0,
+                                          u32 sw_if_index0,
+                                          vlib_node_runtime_t * node,
+                                          u32 next0,
+                                          u32 rx_fib_index0)
+{
+  snat_session_key_t key0, sm0;
+  icmp_echo_header_t *echo0;
+  u32 new_addr0, old_addr0;
+  u16 old_id0, new_id0;
+  ip_csum_t sum0;
+  snat_runtime_t * rt = (snat_runtime_t *)node->runtime_data;
+
+  echo0 = (icmp_echo_header_t *)(icmp0+1);
+
+  key0.addr = ip0->src_address;
+  key0.port = echo0->identifier;
+  key0.fib_index = rx_fib_index0;
+  
+  if (snat_static_mapping_match(sm, key0, &sm0, 0))
+    {
+      ip4_address_t * first_int_addr;
+
+      if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+        {
+          first_int_addr =
+            ip4_interface_first_address (sm->ip4_main, sw_if_index0,
+                                         0 /* just want the address */);
+          rt->cached_sw_if_index = sw_if_index0;
+          rt->cached_ip4_address = first_int_addr->as_u32;
+        }
+
+      /* Don't NAT packet aimed at the intfc address */
+      if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
+                                rt->cached_ip4_address))
+        return next0;
+
+      b0->error = node->errors[SNAT_IN2OUT_ERROR_NO_TRANSLATION];
+      return SNAT_IN2OUT_NEXT_DROP;
+    }
+
+  new_addr0 = sm0.addr.as_u32;
+  new_id0 = sm0.port;
+  vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
+  old_addr0 = ip0->src_address.as_u32;
+  ip0->src_address.as_u32 = new_addr0;
+  
+  sum0 = ip0->checksum;
+  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                         ip4_header_t,
+                         src_address /* changed member */);
+  ip0->checksum = ip_csum_fold (sum0);
+  
+  if (PREDICT_FALSE(new_id0 != echo0->identifier))
+    {
+      old_id0 = echo0->identifier;
+      echo0->identifier = new_id0;
+
+      sum0 = icmp0->checksum;
+      sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
+                             identifier);
+      icmp0->checksum = ip_csum_fold (sum0);
+    }
+
+  return next0;
+}
+
+static uword
+snat_in2out_fast_static_map_fn (vlib_main_t * vm,
+                                vlib_node_runtime_t * node,
+                                vlib_frame_t * frame)
+{
+  u32 n_left_from, * from, * to_next;
+  snat_in2out_next_t next_index;
+  u32 pkts_processed = 0;
+  snat_main_t * sm = &snat_main;
+  snat_runtime_t * rt = (snat_runtime_t *)node->runtime_data;
+  u32 stats_node_index;
+
+  stats_node_index = snat_in2out_fast_node.index;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
+
+      vlib_get_next_frame (vm, node, next_index,
+			   to_next, n_left_to_next);
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+          u32 bi0;
+	  vlib_buffer_t * b0;
+          u32 next0;
+          u32 sw_if_index0;
+          ip4_header_t * ip0;
+          ip_csum_t sum0;
+          u32 new_addr0, old_addr0;
+          u16 old_port0, new_port0;
+          udp_header_t * udp0;
+          tcp_header_t * tcp0;
+          icmp46_header_t * icmp0;
+          snat_session_key_t key0, sm0;
+          u32 proto0;
+          u32 rx_fib_index0;
+
+          /* speculatively enqueue b0 to the current next frame */
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+          next0 = SNAT_IN2OUT_NEXT_LOOKUP;
+
+          ip0 = vlib_buffer_get_current (b0);
+          udp0 = ip4_next_header (ip0);
+          tcp0 = (tcp_header_t *) udp0;
+          icmp0 = (icmp46_header_t *) udp0;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+	  rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index0);
+
+          proto0 = ~0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_UDP)
+            ? SNAT_PROTOCOL_UDP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_TCP)
+            ? SNAT_PROTOCOL_TCP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_ICMP)
+            ? SNAT_PROTOCOL_ICMP : proto0;
+
+          if (PREDICT_FALSE (proto0 == ~0))
+              goto trace0;
+
+          if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+            {
+              ip4_address_t * first_int_addr;
+              
+              if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+                {
+                  first_int_addr = 
+                    ip4_interface_first_address (sm->ip4_main, sw_if_index0,
+                                                 0 /* just want the address */);
+                  rt->cached_sw_if_index = sw_if_index0;
+                  rt->cached_ip4_address = first_int_addr->as_u32;
+                }
+              
+              /* Don't NAT packet aimed at the intfc address */
+              if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
+                                rt->cached_ip4_address))
+                goto trace0;
+
+              next0 = icmp_in2out_static_map
+                (sm, b0, ip0, icmp0, sw_if_index0, node, next0, rx_fib_index0);
+              goto trace0;
+            }
+
+          key0.addr = ip0->src_address;
+          key0.port = udp0->src_port;
+          key0.fib_index = rx_fib_index0;
+
+          if (snat_static_mapping_match(sm, key0, &sm0, 0))
+            {
+              b0->error = node->errors[SNAT_IN2OUT_ERROR_NO_TRANSLATION];
+              next0= SNAT_IN2OUT_NEXT_DROP;
+              goto trace0;
+            }
+
+          new_addr0 = sm0.addr.as_u32;
+          new_port0 = sm0.port;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
+          old_addr0 = ip0->src_address.as_u32;
+          ip0->src_address.as_u32 = new_addr0;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                 ip4_header_t,
+                                 src_address /* changed member */);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_FALSE(new_port0 != udp0->dst_port))
+            {
+              if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+                {
+                  old_port0 = tcp0->ports.src;
+                  tcp0->ports.src = new_port0;
+
+                  sum0 = tcp0->checksum;
+                  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                         ip4_header_t,
+                                         dst_address /* changed member */);
+                  sum0 = ip_csum_update (sum0, old_port0, new_port0,
+                                         ip4_header_t /* cheat */,
+                                         length /* changed member */);
+                  tcp0->checksum = ip_csum_fold(sum0);
+                }
+              else
+                {
+                  old_port0 = udp0->src_port;
+                  udp0->src_port = new_port0;
+                  udp0->checksum = 0;
+                }
+            }
+          else
+            {
+              if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+                {
+                  sum0 = tcp0->checksum;
+                  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                         ip4_header_t,
+                                         dst_address /* changed member */);
+                  tcp0->checksum = ip_csum_fold(sum0);
+                }
+            }
+
+          /* Hairpinning */
+          snat_hairpinning (sm, b0, ip0, udp0, tcp0, proto0);
+
+        trace0:
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+            {
+              snat_in2out_trace_t *t =
+                 vlib_add_trace (vm, node, b0, sizeof (*t));
+              t->sw_if_index = sw_if_index0;
+              t->next_index = next0;
+            }
+
+          pkts_processed += next0 != SNAT_IN2OUT_NEXT_DROP;
+
+          /* verify speculative enqueue, maybe switch current next frame */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_node_increment_counter (vm, stats_node_index,
+                               SNAT_IN2OUT_ERROR_IN2OUT_PACKETS,
+                               pkts_processed);
+  return frame->n_vectors;
+}
+
+
+VLIB_REGISTER_NODE (snat_in2out_fast_node) = {
+  .function = snat_in2out_fast_static_map_fn,
+  .name = "snat-in2out-fast",
+  .vector_size = sizeof (u32),
+  .format_trace = format_snat_in2out_fast_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  
+  .n_errors = ARRAY_LEN(snat_in2out_error_strings),
+  .error_strings = snat_in2out_error_strings,
+
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+  
+  .n_next_nodes = SNAT_IN2OUT_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [SNAT_IN2OUT_NEXT_DROP] = "error-drop",
+    [SNAT_IN2OUT_NEXT_LOOKUP] = "ip4-lookup",
+    [SNAT_IN2OUT_NEXT_SLOW_PATH] = "snat-in2out-slowpath",
+  },
+};
+
+VLIB_NODE_FUNCTION_MULTIARCH (snat_in2out_fast_node, snat_in2out_fast_static_map_fn);
diff --git a/src/plugins/snat/out2in.c b/src/plugins/snat/out2in.c
new file mode 100644
index 00000000000..f1f4159cdce
--- /dev/null
+++ b/src/plugins/snat/out2in.c
@@ -0,0 +1,1261 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vlib/vlib.h>
+#include <vnet/vnet.h>
+#include <vnet/pg/pg.h>
+#include <vnet/handoff.h>
+
+#include <vnet/ip/ip.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/fib/ip4_fib.h>
+#include <snat/snat.h>
+
+#include <vppinfra/hash.h>
+#include <vppinfra/error.h>
+#include <vppinfra/elog.h>
+
+typedef struct {
+  u32 sw_if_index;
+  u32 next_index;
+  u32 session_index;
+} snat_out2in_trace_t;
+
+typedef struct {
+  u32 next_worker_index;
+  u8 do_handoff;
+} snat_out2in_worker_handoff_trace_t;
+
+/* packet trace format function */
+static u8 * format_snat_out2in_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  snat_out2in_trace_t * t = va_arg (*args, snat_out2in_trace_t *);
+  
+  s = format (s, "SNAT_OUT2IN: sw_if_index %d, next index %d, session index %d",
+              t->sw_if_index, t->next_index, t->session_index);
+  return s;
+}
+
+static u8 * format_snat_out2in_fast_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  snat_out2in_trace_t * t = va_arg (*args, snat_out2in_trace_t *);
+  
+  s = format (s, "SNAT_OUT2IN_FAST: sw_if_index %d, next index %d",
+              t->sw_if_index, t->next_index);
+  return s;
+}
+
+static u8 * format_snat_out2in_worker_handoff_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  snat_out2in_worker_handoff_trace_t * t =
+    va_arg (*args, snat_out2in_worker_handoff_trace_t *);
+  char * m;
+
+  m = t->do_handoff ? "next worker" : "same worker";
+  s = format (s, "SNAT_OUT2IN_WORKER_HANDOFF: %s %d", m, t->next_worker_index);
+
+  return s;
+}
+
+vlib_node_registration_t snat_out2in_node;
+vlib_node_registration_t snat_out2in_fast_node;
+vlib_node_registration_t snat_out2in_worker_handoff_node;
+
+#define foreach_snat_out2in_error                       \
+_(UNSUPPORTED_PROTOCOL, "Unsupported protocol")         \
+_(OUT2IN_PACKETS, "Good out2in packets processed")      \
+_(BAD_ICMP_TYPE, "icmp type not echo-reply")            \
+_(NO_TRANSLATION, "No translation")
+  
+typedef enum {
+#define _(sym,str) SNAT_OUT2IN_ERROR_##sym,
+  foreach_snat_out2in_error
+#undef _
+  SNAT_OUT2IN_N_ERROR,
+} snat_out2in_error_t;
+
+static char * snat_out2in_error_strings[] = {
+#define _(sym,string) string,
+  foreach_snat_out2in_error
+#undef _
+};
+
+typedef enum {
+  SNAT_OUT2IN_NEXT_DROP,
+  SNAT_OUT2IN_NEXT_LOOKUP,
+  SNAT_OUT2IN_N_NEXT,
+} snat_out2in_next_t;
+
+/**
+ * @brief Create session for static mapping.
+ *
+ * Create NAT session initiated by host from external network with static
+ * mapping.
+ *
+ * @param sm     SNAT main.
+ * @param b0     Vlib buffer.
+ * @param in2out In2out SNAT session key.
+ * @param out2in Out2in SNAT session key.
+ * @param node   Vlib node.
+ *
+ * @returns SNAT session if successfully created otherwise 0.
+ */
+static inline snat_session_t *
+create_session_for_static_mapping (snat_main_t *sm,
+                                   vlib_buffer_t *b0,
+                                   snat_session_key_t in2out,
+                                   snat_session_key_t out2in,
+                                   vlib_node_runtime_t * node,
+                                   u32 cpu_index)
+{
+  snat_user_t *u;
+  snat_user_key_t user_key;
+  snat_session_t *s;
+  clib_bihash_kv_8_8_t kv0, value0;
+  dlist_elt_t * per_user_translation_list_elt;
+  dlist_elt_t * per_user_list_head_elt;
+
+  user_key.addr = in2out.addr;
+  user_key.fib_index = in2out.fib_index;
+  kv0.key = user_key.as_u64;
+
+  /* Ever heard of the "user" = inside ip4 address before? */
+  if (clib_bihash_search_8_8 (&sm->user_hash, &kv0, &value0))
+    {
+      /* no, make a new one */
+      pool_get (sm->per_thread_data[cpu_index].users, u);
+      memset (u, 0, sizeof (*u));
+      u->addr = in2out.addr;
+
+      pool_get (sm->per_thread_data[cpu_index].list_pool,
+                per_user_list_head_elt);
+
+      u->sessions_per_user_list_head_index = per_user_list_head_elt -
+        sm->per_thread_data[cpu_index].list_pool;
+
+      clib_dlist_init (sm->per_thread_data[cpu_index].list_pool,
+                       u->sessions_per_user_list_head_index);
+
+      kv0.value = u - sm->per_thread_data[cpu_index].users;
+
+      /* add user */
+      clib_bihash_add_del_8_8 (&sm->user_hash, &kv0, 1 /* is_add */);
+
+      /* add non-traslated packets worker lookup */
+      kv0.value = cpu_index;
+      clib_bihash_add_del_8_8 (&sm->worker_by_in, &kv0, 1);
+    }
+  else
+    {
+      u = pool_elt_at_index (sm->per_thread_data[cpu_index].users,
+                             value0.value);
+    }
+
+  pool_get (sm->per_thread_data[cpu_index].sessions, s);
+  memset (s, 0, sizeof (*s));
+
+  s->outside_address_index = ~0;
+  s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
+  u->nstaticsessions++;
+
+  /* Create list elts */
+  pool_get (sm->per_thread_data[cpu_index].list_pool,
+            per_user_translation_list_elt);
+  clib_dlist_init (sm->per_thread_data[cpu_index].list_pool,
+                   per_user_translation_list_elt -
+                   sm->per_thread_data[cpu_index].list_pool);
+
+  per_user_translation_list_elt->value =
+    s - sm->per_thread_data[cpu_index].sessions;
+  s->per_user_index =
+    per_user_translation_list_elt - sm->per_thread_data[cpu_index].list_pool;
+  s->per_user_list_head_index = u->sessions_per_user_list_head_index;
+
+  clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                      s->per_user_list_head_index,
+                      per_user_translation_list_elt -
+                      sm->per_thread_data[cpu_index].list_pool);
+
+  s->in2out = in2out;
+  s->out2in = out2in;
+  s->in2out.protocol = out2in.protocol;
+
+  /* Add to translation hashes */
+  kv0.key = s->in2out.as_u64;
+  kv0.value = s - sm->per_thread_data[cpu_index].sessions;
+  if (clib_bihash_add_del_8_8 (&sm->in2out, &kv0, 1 /* is_add */))
+      clib_warning ("in2out key add failed");
+
+  kv0.key = s->out2in.as_u64;
+  kv0.value = s - sm->per_thread_data[cpu_index].sessions;
+
+  if (clib_bihash_add_del_8_8 (&sm->out2in, &kv0, 1 /* is_add */))
+      clib_warning ("out2in key add failed");
+
+  return s;
+}
+
+static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
+                                         vlib_buffer_t * b0,
+                                         ip4_header_t * ip0,
+                                         icmp46_header_t * icmp0,
+                                         u32 sw_if_index0,
+                                         u32 rx_fib_index0,
+                                         vlib_node_runtime_t * node,
+                                         u32 next0, f64 now,
+                                         u32 cpu_index)
+{
+  snat_session_key_t key0, sm0;
+  icmp_echo_header_t *echo0;
+  clib_bihash_kv_8_8_t kv0, value0;
+  snat_session_t * s0;
+  u32 new_addr0, old_addr0;
+  u16 old_id0, new_id0;
+  ip_csum_t sum0;
+  snat_runtime_t * rt = (snat_runtime_t *)node->runtime_data;
+
+  echo0 = (icmp_echo_header_t *)(icmp0+1);
+
+  key0.addr = ip0->dst_address;
+  key0.port = echo0->identifier;
+  key0.protocol = SNAT_PROTOCOL_ICMP;
+  key0.fib_index = rx_fib_index0;
+  
+  kv0.key = key0.as_u64;
+  
+  if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
+    {
+      /* Try to match static mapping by external address and port,
+         destination address and port in packet */
+      if (snat_static_mapping_match(sm, key0, &sm0, 1))
+        {
+           ip4_address_t * first_int_addr;
+
+          if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+            {
+              first_int_addr = 
+                ip4_interface_first_address (sm->ip4_main, sw_if_index0,
+                                             0 /* just want the address */);
+              rt->cached_sw_if_index = sw_if_index0;
+              rt->cached_ip4_address = first_int_addr->as_u32;
+            }
+          
+          /* Don't NAT packet aimed at the intfc address */
+          if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
+                            rt->cached_ip4_address))
+            return next0;
+
+          b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+          return SNAT_OUT2IN_NEXT_DROP;
+        }
+
+      /* Create session initiated by host from external network */
+      s0 = create_session_for_static_mapping(sm, b0, sm0, key0,
+                                             node, cpu_index);
+      if (!s0)
+        return SNAT_OUT2IN_NEXT_DROP;
+    }
+  else
+    s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
+                            value0.value);
+
+  old_addr0 = ip0->dst_address.as_u32;
+  ip0->dst_address = s0->in2out.addr;
+  new_addr0 = ip0->dst_address.as_u32;
+  vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
+  
+  sum0 = ip0->checksum;
+  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                         ip4_header_t,
+                         dst_address /* changed member */);
+  ip0->checksum = ip_csum_fold (sum0);
+  
+  old_id0 = echo0->identifier;
+  new_id0 = s0->in2out.port;
+  echo0->identifier = new_id0;
+
+  sum0 = icmp0->checksum;
+  sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
+                         identifier);
+  icmp0->checksum = ip_csum_fold (sum0);
+
+  /* Accounting */
+  s0->last_heard = now;
+  s0->total_pkts++;
+  s0->total_bytes += vlib_buffer_length_in_chain (sm->vlib_main, b0);
+  /* Per-user LRU list maintenance for dynamic translation */
+  if (!snat_is_session_static (s0))
+    {
+      clib_dlist_remove (sm->per_thread_data[cpu_index].list_pool,
+                         s0->per_user_index);
+      clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                          s0->per_user_list_head_index,
+                          s0->per_user_index);
+    }
+
+  return next0;
+}
+
+static uword
+snat_out2in_node_fn (vlib_main_t * vm,
+		  vlib_node_runtime_t * node,
+		  vlib_frame_t * frame)
+{
+  u32 n_left_from, * from, * to_next;
+  snat_out2in_next_t next_index;
+  u32 pkts_processed = 0;
+  snat_main_t * sm = &snat_main;
+  f64 now = vlib_time_now (vm);
+  u32 cpu_index = os_get_cpu_number ();
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
+
+      vlib_get_next_frame (vm, node, next_index,
+			   to_next, n_left_to_next);
+
+      while (n_left_from >= 4 && n_left_to_next >= 2)
+	{
+          u32 bi0, bi1;
+	  vlib_buffer_t * b0, * b1;
+          u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
+          u32 next1 = SNAT_OUT2IN_NEXT_LOOKUP;
+          u32 sw_if_index0, sw_if_index1;
+          ip4_header_t * ip0, *ip1;
+          ip_csum_t sum0, sum1;
+          u32 new_addr0, old_addr0;
+          u16 new_port0, old_port0;
+          u32 new_addr1, old_addr1;
+          u16 new_port1, old_port1;
+          udp_header_t * udp0, * udp1;
+          tcp_header_t * tcp0, * tcp1;
+          icmp46_header_t * icmp0, * icmp1;
+          snat_session_key_t key0, key1, sm0, sm1;
+          u32 rx_fib_index0, rx_fib_index1;
+          u32 proto0, proto1;
+          snat_session_t * s0 = 0, * s1 = 0;
+          clib_bihash_kv_8_8_t kv0, kv1, value0, value1;
+          
+	  /* Prefetch next iteration. */
+	  {
+	    vlib_buffer_t * p2, * p3;
+            
+	    p2 = vlib_get_buffer (vm, from[2]);
+	    p3 = vlib_get_buffer (vm, from[3]);
+            
+	    vlib_prefetch_buffer_header (p2, LOAD);
+	    vlib_prefetch_buffer_header (p3, LOAD);
+
+	    CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
+	    CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
+	  }
+
+          /* speculatively enqueue b0 and b1 to the current next frame */
+	  to_next[0] = bi0 = from[0];
+	  to_next[1] = bi1 = from[1];
+	  from += 2;
+	  to_next += 2;
+	  n_left_from -= 2;
+	  n_left_to_next -= 2;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+	  b1 = vlib_get_buffer (vm, bi1);
+            
+          ip0 = vlib_buffer_get_current (b0);
+          udp0 = ip4_next_header (ip0);
+          tcp0 = (tcp_header_t *) udp0;
+          icmp0 = (icmp46_header_t *) udp0;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+	  rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index, 
+                                   sw_if_index0);
+
+          proto0 = ~0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_UDP) 
+            ? SNAT_PROTOCOL_UDP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_TCP) 
+            ? SNAT_PROTOCOL_TCP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_ICMP) 
+            ? SNAT_PROTOCOL_ICMP : proto0;
+
+          if (PREDICT_FALSE (proto0 == ~0))
+              goto trace0;
+
+          if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+            {
+              next0 = icmp_out2in_slow_path 
+                (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node, 
+                 next0, now, cpu_index);
+              goto trace0;
+            }
+
+          key0.addr = ip0->dst_address;
+          key0.port = udp0->dst_port;
+          key0.protocol = proto0;
+          key0.fib_index = rx_fib_index0;
+          
+          kv0.key = key0.as_u64;
+
+          if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
+            {
+              /* Try to match static mapping by external address and port,
+                 destination address and port in packet */
+              if (snat_static_mapping_match(sm, key0, &sm0, 1))
+                {
+                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  goto trace0;
+                }
+
+              /* Create session initiated by host from external network */
+              s0 = create_session_for_static_mapping(sm, b0, sm0, key0, node,
+                                                     cpu_index);
+              if (!s0)
+                goto trace0;
+            }
+          else
+            s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
+                                    value0.value);
+
+          old_addr0 = ip0->dst_address.as_u32;
+          ip0->dst_address = s0->in2out.addr;
+          new_addr0 = ip0->dst_address.as_u32;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                 ip4_header_t,
+                                 dst_address /* changed member */);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+            {
+              old_port0 = tcp0->ports.dst;
+              tcp0->ports.dst = s0->in2out.port;
+              new_port0 = tcp0->ports.dst;
+
+              sum0 = tcp0->checksum;
+              sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                     ip4_header_t,
+                                     dst_address /* changed member */);
+
+              sum0 = ip_csum_update (sum0, old_port0, new_port0,
+                                     ip4_header_t /* cheat */,
+                                     length /* changed member */);
+              tcp0->checksum = ip_csum_fold(sum0);
+            }
+          else
+            {
+              old_port0 = udp0->dst_port;
+              udp0->dst_port = s0->in2out.port;
+              udp0->checksum = 0;
+            }
+
+          /* Accounting */
+          s0->last_heard = now;
+          s0->total_pkts++;
+          s0->total_bytes += vlib_buffer_length_in_chain (vm, b0);
+          /* Per-user LRU list maintenance for dynamic translation */
+          if (!snat_is_session_static (s0))
+            {
+              clib_dlist_remove (sm->per_thread_data[cpu_index].list_pool,
+                                 s0->per_user_index);
+              clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                                  s0->per_user_list_head_index,
+                                  s0->per_user_index);
+            }
+        trace0:
+
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED))) 
+            {
+              snat_out2in_trace_t *t = 
+                 vlib_add_trace (vm, node, b0, sizeof (*t));
+              t->sw_if_index = sw_if_index0;
+              t->next_index = next0;
+              t->session_index = ~0;
+              if (s0)
+                t->session_index = s0 - sm->per_thread_data[cpu_index].sessions;
+            }
+
+          pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
+
+
+          ip1 = vlib_buffer_get_current (b1);
+          udp1 = ip4_next_header (ip1);
+          tcp1 = (tcp_header_t *) udp1;
+          icmp1 = (icmp46_header_t *) udp1;
+
+          sw_if_index1 = vnet_buffer(b1)->sw_if_index[VLIB_RX];
+	  rx_fib_index1 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index, 
+                                   sw_if_index1);
+
+          proto1 = ~0;
+          proto1 = (ip1->protocol == IP_PROTOCOL_UDP) 
+            ? SNAT_PROTOCOL_UDP : proto1;
+          proto1 = (ip1->protocol == IP_PROTOCOL_TCP) 
+            ? SNAT_PROTOCOL_TCP : proto1;
+          proto1 = (ip1->protocol == IP_PROTOCOL_ICMP) 
+            ? SNAT_PROTOCOL_ICMP : proto1;
+
+          if (PREDICT_FALSE (proto1 == ~0))
+              goto trace1;
+
+          if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
+            {
+              next1 = icmp_out2in_slow_path 
+                (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node, 
+                 next1, now, cpu_index);
+              goto trace1;
+            }
+
+          key1.addr = ip1->dst_address;
+          key1.port = udp1->dst_port;
+          key1.protocol = proto1;
+          key1.fib_index = rx_fib_index1;
+          
+          kv1.key = key1.as_u64;
+
+          if (clib_bihash_search_8_8 (&sm->out2in, &kv1, &value1))
+            {
+              /* Try to match static mapping by external address and port,
+                 destination address and port in packet */
+              if (snat_static_mapping_match(sm, key1, &sm1, 1))
+                {
+                  b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  goto trace1;
+                }
+
+              /* Create session initiated by host from external network */
+              s1 = create_session_for_static_mapping(sm, b1, sm1, key1, node,
+                                                     cpu_index);
+              if (!s1)
+                goto trace1;
+            }
+          else
+            s1 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
+                                    value1.value);
+
+          old_addr1 = ip1->dst_address.as_u32;
+          ip1->dst_address = s1->in2out.addr;
+          new_addr1 = ip1->dst_address.as_u32;
+          vnet_buffer(b1)->sw_if_index[VLIB_TX] = s1->in2out.fib_index;
+
+          sum1 = ip1->checksum;
+          sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
+                                 ip4_header_t,
+                                 dst_address /* changed member */);
+          ip1->checksum = ip_csum_fold (sum1);
+
+          if (PREDICT_TRUE(proto1 == SNAT_PROTOCOL_TCP))
+            {
+              old_port1 = tcp1->ports.dst;
+              tcp1->ports.dst = s1->in2out.port;
+              new_port1 = tcp1->ports.dst;
+
+              sum1 = tcp1->checksum;
+              sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
+                                     ip4_header_t,
+                                     dst_address /* changed member */);
+
+              sum1 = ip_csum_update (sum1, old_port1, new_port1,
+                                     ip4_header_t /* cheat */,
+                                     length /* changed member */);
+              tcp1->checksum = ip_csum_fold(sum1);
+            }
+          else
+            {
+              old_port1 = udp1->dst_port;
+              udp1->dst_port = s1->in2out.port;
+              udp1->checksum = 0;
+            }
+
+          /* Accounting */
+          s1->last_heard = now;
+          s1->total_pkts++;
+          s1->total_bytes += vlib_buffer_length_in_chain (vm, b1);
+          /* Per-user LRU list maintenance for dynamic translation */
+          if (!snat_is_session_static (s1))
+            {
+              clib_dlist_remove (sm->per_thread_data[cpu_index].list_pool,
+                                 s1->per_user_index);
+              clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                                  s1->per_user_list_head_index,
+                                  s1->per_user_index);
+            }
+        trace1:
+
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
+                            && (b1->flags & VLIB_BUFFER_IS_TRACED))) 
+            {
+              snat_out2in_trace_t *t = 
+                 vlib_add_trace (vm, node, b1, sizeof (*t));
+              t->sw_if_index = sw_if_index1;
+              t->next_index = next1;
+              t->session_index = ~0;
+              if (s1)
+                t->session_index = s1 - sm->per_thread_data[cpu_index].sessions;
+            }
+
+          pkts_processed += next1 != SNAT_OUT2IN_NEXT_DROP;
+
+          /* verify speculative enqueues, maybe switch current next frame */
+          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
+                                           to_next, n_left_to_next,
+                                           bi0, bi1, next0, next1);
+        }
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+          u32 bi0;
+	  vlib_buffer_t * b0;
+          u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
+          u32 sw_if_index0;
+          ip4_header_t * ip0;
+          ip_csum_t sum0;
+          u32 new_addr0, old_addr0;
+          u16 new_port0, old_port0;
+          udp_header_t * udp0;
+          tcp_header_t * tcp0;
+          icmp46_header_t * icmp0;
+          snat_session_key_t key0, sm0;
+          u32 rx_fib_index0;
+          u32 proto0;
+          snat_session_t * s0 = 0;
+          clib_bihash_kv_8_8_t kv0, value0;
+          
+          /* speculatively enqueue b0 to the current next frame */
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+
+          ip0 = vlib_buffer_get_current (b0);
+          udp0 = ip4_next_header (ip0);
+          tcp0 = (tcp_header_t *) udp0;
+          icmp0 = (icmp46_header_t *) udp0;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+	  rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index, 
+                                   sw_if_index0);
+
+          proto0 = ~0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_UDP) 
+            ? SNAT_PROTOCOL_UDP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_TCP) 
+            ? SNAT_PROTOCOL_TCP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_ICMP) 
+            ? SNAT_PROTOCOL_ICMP : proto0;
+
+          if (PREDICT_FALSE (proto0 == ~0))
+              goto trace00;
+
+          if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+            {
+              next0 = icmp_out2in_slow_path 
+                (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node, 
+                 next0, now, cpu_index);
+              goto trace00;
+            }
+
+          key0.addr = ip0->dst_address;
+          key0.port = udp0->dst_port;
+          key0.protocol = proto0;
+          key0.fib_index = rx_fib_index0;
+          
+          kv0.key = key0.as_u64;
+
+          if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
+            {
+              /* Try to match static mapping by external address and port,
+                 destination address and port in packet */
+              if (snat_static_mapping_match(sm, key0, &sm0, 1))
+                {
+                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  goto trace00;
+                }
+
+              /* Create session initiated by host from external network */
+              s0 = create_session_for_static_mapping(sm, b0, sm0, key0, node,
+                                                     cpu_index);
+              if (!s0)
+                goto trace00;
+            }
+          else
+            s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
+                                    value0.value);
+
+          old_addr0 = ip0->dst_address.as_u32;
+          ip0->dst_address = s0->in2out.addr;
+          new_addr0 = ip0->dst_address.as_u32;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                 ip4_header_t,
+                                 dst_address /* changed member */);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+            {
+              old_port0 = tcp0->ports.dst;
+              tcp0->ports.dst = s0->in2out.port;
+              new_port0 = tcp0->ports.dst;
+
+              sum0 = tcp0->checksum;
+              sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                     ip4_header_t,
+                                     dst_address /* changed member */);
+
+              sum0 = ip_csum_update (sum0, old_port0, new_port0,
+                                     ip4_header_t /* cheat */,
+                                     length /* changed member */);
+              tcp0->checksum = ip_csum_fold(sum0);
+            }
+          else
+            {
+              old_port0 = udp0->dst_port;
+              udp0->dst_port = s0->in2out.port;
+              udp0->checksum = 0;
+            }
+
+          /* Accounting */
+          s0->last_heard = now;
+          s0->total_pkts++;
+          s0->total_bytes += vlib_buffer_length_in_chain (vm, b0);
+          /* Per-user LRU list maintenance for dynamic translation */
+          if (!snat_is_session_static (s0))
+            {
+              clib_dlist_remove (sm->per_thread_data[cpu_index].list_pool,
+                                 s0->per_user_index);
+              clib_dlist_addtail (sm->per_thread_data[cpu_index].list_pool,
+                                  s0->per_user_list_head_index,
+                                  s0->per_user_index);
+            }
+        trace00:
+
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED))) 
+            {
+              snat_out2in_trace_t *t = 
+                 vlib_add_trace (vm, node, b0, sizeof (*t));
+              t->sw_if_index = sw_if_index0;
+              t->next_index = next0;
+              t->session_index = ~0;
+              if (s0)
+                t->session_index = s0 - sm->per_thread_data[cpu_index].sessions;
+            }
+
+          pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
+
+          /* verify speculative enqueue, maybe switch current next frame */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_node_increment_counter (vm, snat_out2in_node.index, 
+                               SNAT_OUT2IN_ERROR_OUT2IN_PACKETS, 
+                               pkts_processed);
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (snat_out2in_node) = {
+  .function = snat_out2in_node_fn,
+  .name = "snat-out2in",
+  .vector_size = sizeof (u32),
+  .format_trace = format_snat_out2in_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  
+  .n_errors = ARRAY_LEN(snat_out2in_error_strings),
+  .error_strings = snat_out2in_error_strings,
+
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+  
+  .n_next_nodes = SNAT_OUT2IN_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
+    [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
+  },
+};
+VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_node, snat_out2in_node_fn);
+
+static uword
+snat_out2in_worker_handoff_fn (vlib_main_t * vm,
+                               vlib_node_runtime_t * node,
+                               vlib_frame_t * frame)
+{
+  snat_main_t *sm = &snat_main;
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+  u32 n_left_from, *from, *to_next = 0;
+  static __thread vlib_frame_queue_elt_t **handoff_queue_elt_by_worker_index;
+  static __thread vlib_frame_queue_t **congested_handoff_queue_by_worker_index
+    = 0;
+  vlib_frame_queue_elt_t *hf = 0;
+  vlib_frame_t *f = 0;
+  int i;
+  u32 n_left_to_next_worker = 0, *to_next_worker = 0;
+  u32 next_worker_index = 0;
+  u32 current_worker_index = ~0;
+  u32 cpu_index = os_get_cpu_number ();
+
+  ASSERT (vec_len (sm->workers));
+
+  if (PREDICT_FALSE (handoff_queue_elt_by_worker_index == 0))
+    {
+      vec_validate (handoff_queue_elt_by_worker_index, tm->n_vlib_mains - 1);
+
+      vec_validate_init_empty (congested_handoff_queue_by_worker_index,
+			       sm->first_worker_index + sm->num_workers - 1,
+			       (vlib_frame_queue_t *) (~0));
+    }
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+
+  while (n_left_from > 0)
+    {
+      u32 bi0;
+      vlib_buffer_t *b0;
+      u32 sw_if_index0;
+      u32 rx_fib_index0;
+      ip4_header_t * ip0;
+      udp_header_t * udp0;
+      snat_static_mapping_key_t key0;
+      clib_bihash_kv_8_8_t kv0, value0;
+      u8 do_handoff;
+
+      bi0 = from[0];
+      from += 1;
+      n_left_from -= 1;
+
+      b0 = vlib_get_buffer (vm, bi0);
+
+      sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+      rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index0);
+
+      ip0 = vlib_buffer_get_current (b0);
+      udp0 = ip4_next_header (ip0);
+
+      key0.addr = ip0->dst_address;
+      key0.port = udp0->dst_port;
+      key0.fib_index = rx_fib_index0;
+
+      kv0.key = key0.as_u64;
+
+      /* Ever heard of of the "user" before? */
+      if (clib_bihash_search_8_8 (&sm->worker_by_out, &kv0, &value0))
+        {
+          key0.port = 0;
+          kv0.key = key0.as_u64;
+
+          if (clib_bihash_search_8_8 (&sm->worker_by_out, &kv0, &value0))
+            {
+              /* No, assign next available worker (RR) */
+              next_worker_index = sm->first_worker_index +
+                sm->workers[sm->next_worker++ % vec_len (sm->workers)];
+            }
+          else
+            {
+              /* Static mapping without port */
+              next_worker_index = value0.value;
+            }
+
+          /* Add to translated packets worker lookup */
+          kv0.value = next_worker_index;
+          clib_bihash_add_del_8_8 (&sm->worker_by_out, &kv0, 1);
+        }
+      else
+        next_worker_index = value0.value;
+
+      if (PREDICT_FALSE (next_worker_index != cpu_index))
+        {
+          do_handoff = 1;
+
+          if (next_worker_index != current_worker_index)
+            {
+              if (hf)
+                hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;
+
+              hf = vlib_get_worker_handoff_queue_elt (sm->fq_out2in_index,
+                                                      next_worker_index,
+                                                      handoff_queue_elt_by_worker_index);
+
+              n_left_to_next_worker = VLIB_FRAME_SIZE - hf->n_vectors;
+              to_next_worker = &hf->buffer_index[hf->n_vectors];
+              current_worker_index = next_worker_index;
+            }
+
+          /* enqueue to correct worker thread */
+          to_next_worker[0] = bi0;
+          to_next_worker++;
+          n_left_to_next_worker--;
+
+          if (n_left_to_next_worker == 0)
+            {
+              hf->n_vectors = VLIB_FRAME_SIZE;
+              vlib_put_frame_queue_elt (hf);
+              current_worker_index = ~0;
+              handoff_queue_elt_by_worker_index[next_worker_index] = 0;
+              hf = 0;
+            }
+        }
+      else
+        {
+          do_handoff = 0;
+          /* if this is 1st frame */
+          if (!f)
+            {
+              f = vlib_get_frame_to_node (vm, snat_out2in_node.index);
+              to_next = vlib_frame_vector_args (f);
+            }
+
+          to_next[0] = bi0;
+          to_next += 1;
+          f->n_vectors++;
+        }
+
+      if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+			 && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+	{
+          snat_out2in_worker_handoff_trace_t *t =
+            vlib_add_trace (vm, node, b0, sizeof (*t));
+          t->next_worker_index = next_worker_index;
+          t->do_handoff = do_handoff;
+        }
+    }
+
+  if (f)
+    vlib_put_frame_to_node (vm, snat_out2in_node.index, f);
+
+  if (hf)
+    hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;
+
+  /* Ship frames to the worker nodes */
+  for (i = 0; i < vec_len (handoff_queue_elt_by_worker_index); i++)
+    {
+      if (handoff_queue_elt_by_worker_index[i])
+	{
+	  hf = handoff_queue_elt_by_worker_index[i];
+	  /*
+	   * It works better to let the handoff node
+	   * rate-adapt, always ship the handoff queue element.
+	   */
+	  if (1 || hf->n_vectors == hf->last_n_vectors)
+	    {
+	      vlib_put_frame_queue_elt (hf);
+	      handoff_queue_elt_by_worker_index[i] = 0;
+	    }
+	  else
+	    hf->last_n_vectors = hf->n_vectors;
+	}
+      congested_handoff_queue_by_worker_index[i] =
+	(vlib_frame_queue_t *) (~0);
+    }
+  hf = 0;
+  current_worker_index = ~0;
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (snat_out2in_worker_handoff_node) = {
+  .function = snat_out2in_worker_handoff_fn,
+  .name = "snat-out2in-worker-handoff",
+  .vector_size = sizeof (u32),
+  .format_trace = format_snat_out2in_worker_handoff_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  
+  .n_next_nodes = 1,
+
+  .next_nodes = {
+    [0] = "error-drop",
+  },
+};
+
+VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_worker_handoff_node, snat_out2in_worker_handoff_fn);
+
+static inline u32 icmp_out2in_fast (snat_main_t *sm,
+                                    vlib_buffer_t * b0,
+                                    ip4_header_t * ip0,
+                                    icmp46_header_t * icmp0,
+                                    u32 sw_if_index0,
+                                    vlib_node_runtime_t * node,
+                                    u32 next0,
+                                    u32 rx_fib_index0)
+{
+  snat_session_key_t key0, sm0;
+  icmp_echo_header_t *echo0;
+  u32 new_addr0, old_addr0;
+  u16 old_id0, new_id0;
+  ip_csum_t sum0;
+  snat_runtime_t * rt = (snat_runtime_t *)node->runtime_data;
+
+  echo0 = (icmp_echo_header_t *)(icmp0+1);
+
+  key0.addr = ip0->dst_address;
+  key0.port = echo0->identifier;
+  key0.fib_index = rx_fib_index0;
+
+  if (snat_static_mapping_match(sm, key0, &sm0, 1))
+    {
+      ip4_address_t * first_int_addr;
+
+      if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+        {
+          first_int_addr =
+            ip4_interface_first_address (sm->ip4_main, sw_if_index0,
+                                         0 /* just want the address */);
+          rt->cached_sw_if_index = sw_if_index0;
+          rt->cached_ip4_address = first_int_addr->as_u32;
+        }
+
+      /* Don't NAT packet aimed at the intfc address */
+      if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
+                        rt->cached_ip4_address))
+        return next0;
+
+      b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+      return SNAT_OUT2IN_NEXT_DROP;
+    }
+
+  new_addr0 = sm0.addr.as_u32;
+  new_id0 = sm0.port;
+  vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
+
+  old_addr0 = ip0->dst_address.as_u32;
+  ip0->dst_address.as_u32 = new_addr0;
+
+  sum0 = ip0->checksum;
+  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                         ip4_header_t,
+                         dst_address /* changed member */);
+  ip0->checksum = ip_csum_fold (sum0);
+
+  if (PREDICT_FALSE(new_id0 != echo0->identifier))
+    {
+      old_id0 = echo0->identifier;
+      echo0->identifier = new_id0;
+
+      sum0 = icmp0->checksum;
+      sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
+                             identifier);
+      icmp0->checksum = ip_csum_fold (sum0);
+    }
+
+  return next0;
+}
+
+static uword
+snat_out2in_fast_node_fn (vlib_main_t * vm,
+	        	  vlib_node_runtime_t * node,
+		          vlib_frame_t * frame)
+{
+  u32 n_left_from, * from, * to_next;
+  snat_out2in_next_t next_index;
+  u32 pkts_processed = 0;
+  snat_main_t * sm = &snat_main;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
+
+      vlib_get_next_frame (vm, node, next_index,
+			   to_next, n_left_to_next);
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+          u32 bi0;
+	  vlib_buffer_t * b0;
+          u32 next0 = SNAT_OUT2IN_NEXT_DROP;
+          u32 sw_if_index0;
+          ip4_header_t * ip0;
+          ip_csum_t sum0;
+          u32 new_addr0, old_addr0;
+          u16 new_port0, old_port0;
+          udp_header_t * udp0;
+          tcp_header_t * tcp0;
+          icmp46_header_t * icmp0;
+          snat_session_key_t key0, sm0;
+          u32 proto0;
+          u32 rx_fib_index0;
+
+          /* speculatively enqueue b0 to the current next frame */
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+
+          ip0 = vlib_buffer_get_current (b0);
+          udp0 = ip4_next_header (ip0);
+          tcp0 = (tcp_header_t *) udp0;
+          icmp0 = (icmp46_header_t *) udp0;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+	  rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index0);
+
+	  vnet_feature_next (sw_if_index0, &next0, b0);
+
+          proto0 = ~0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_UDP)
+            ? SNAT_PROTOCOL_UDP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_TCP)
+            ? SNAT_PROTOCOL_TCP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_ICMP)
+            ? SNAT_PROTOCOL_ICMP : proto0;
+
+          if (PREDICT_FALSE (proto0 == ~0))
+              goto trace00;
+
+          if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+            {
+              next0 = icmp_out2in_fast
+                (sm, b0, ip0, icmp0, sw_if_index0, node, next0, rx_fib_index0);
+              goto trace00;
+            }
+
+          key0.addr = ip0->dst_address;
+          key0.port = udp0->dst_port;
+          key0.fib_index = rx_fib_index0;
+
+          if (snat_static_mapping_match(sm, key0, &sm0, 1))
+            {
+              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+              goto trace00;
+            }
+
+          new_addr0 = sm0.addr.as_u32;
+          new_port0 = sm0.port;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
+          old_addr0 = ip0->dst_address.as_u32;
+          ip0->dst_address.as_u32 = new_addr0;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                 ip4_header_t,
+                                 dst_address /* changed member */);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_FALSE(new_port0 != udp0->dst_port))
+            {
+               if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+                {
+                  old_port0 = tcp0->ports.dst;
+                  tcp0->ports.dst = new_port0;
+
+                  sum0 = tcp0->checksum;
+                  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                         ip4_header_t,
+                                         dst_address /* changed member */);
+
+                  sum0 = ip_csum_update (sum0, old_port0, new_port0,
+                                         ip4_header_t /* cheat */,
+                                         length /* changed member */);
+                  tcp0->checksum = ip_csum_fold(sum0);
+                }
+              else
+                {
+                  old_port0 = udp0->dst_port;
+                  udp0->dst_port = new_port0;
+                  udp0->checksum = 0;
+                }
+            }
+          else
+            {
+              if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+                {
+                  sum0 = tcp0->checksum;
+                  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                         ip4_header_t,
+                                         dst_address /* changed member */);
+
+                  tcp0->checksum = ip_csum_fold(sum0);
+                }
+            }
+
+        trace00:
+
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+            {
+              snat_out2in_trace_t *t =
+                 vlib_add_trace (vm, node, b0, sizeof (*t));
+              t->sw_if_index = sw_if_index0;
+              t->next_index = next0;
+            }
+
+          pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
+
+          /* verify speculative enqueue, maybe switch current next frame */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_node_increment_counter (vm, snat_out2in_fast_node.index,
+                               SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
+                               pkts_processed);
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (snat_out2in_fast_node) = {
+  .function = snat_out2in_fast_node_fn,
+  .name = "snat-out2in-fast",
+  .vector_size = sizeof (u32),
+  .format_trace = format_snat_out2in_fast_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  
+  .n_errors = ARRAY_LEN(snat_out2in_error_strings),
+  .error_strings = snat_out2in_error_strings,
+
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+  
+  .n_next_nodes = SNAT_OUT2IN_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
+    [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
+  },
+};
+VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_fast_node, snat_out2in_fast_node_fn);
diff --git a/src/plugins/snat/snat.api b/src/plugins/snat/snat.api
new file mode 100644
index 00000000000..a191eed5944
--- /dev/null
+++ b/src/plugins/snat/snat.api
@@ -0,0 +1,283 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * @file snat.api
+ * @brief VPP control-plane API messages.
+ *
+ * This file defines VPP control-plane API messages which are generally
+ * called through a shared memory interface.
+ */
+
+/** \brief Add/del S-NAT address range
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param is_ip4 - 1 if address type is IPv4
+    @first_ip_address - first IP address
+    @last_ip_address - last IP address
+    @is_add - 1 if add, 0 if delete
+*/
+define snat_add_address_range {
+  u32 client_index;
+  u32 context;
+  u8 is_ip4;
+  u8 first_ip_address[16];
+  u8 last_ip_address[16];
+  u8 is_add;
+};
+
+/** \brief Add S-NAT address range reply
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param retval - return code
+*/
+define snat_add_address_range_reply {
+  u32 context;
+  i32 retval;
+};
+
+/** \brief Dump S-NAT addresses
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+*/
+define snat_address_dump {
+  u32 client_index;
+  u32 context;
+};
+
+/** \brief S-NAT address details response
+    @param context - sender context, to match reply w/ request
+    @param is_ip4 - 1 if address type is IPv4
+    @param ip_address - IP address
+*/
+define snat_address_details {
+  u32 context;
+  u8 is_ip4;
+  u8 ip_address[16];
+};
+
+/** \brief Enable/disable S-NAT feature on the interface
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param is_add - 1 if add, 0 if delete
+    @param is_inside - 1 if inside, 0 if outside
+    @param sw_if_index - software index of the interface
+*/
+define snat_interface_add_del_feature {
+  u32 client_index;
+  u32 context;
+  u8 is_add;
+  u8 is_inside;
+  u32 sw_if_index;
+};
+
+/** \brief Enable/disable S-NAT feature on the interface reply
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param retval - return code
+*/
+define snat_interface_add_del_feature_reply {
+  u32 context;
+  i32 retval;
+};
+
+/** \brief Dump interfaces with S-NAT feature
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+*/
+define snat_interface_dump {
+  u32 client_index;
+  u32 context;
+};
+
+/** \brief S-NAT interface details response
+    @param context - sender context, to match reply w/ request
+    @param is_inside - 1 if inside, 0 if outside
+    @param sw_if_index - software index of the interface
+*/
+define snat_interface_details {
+  u32 context;
+  u8 is_inside;
+  u32 sw_if_index;
+};
+
+/** \brief Add/delete S-NAT static mapping
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param is_add - 1 if add, 0 if delete
+    @param is_ip4 - 1 if address type is IPv4
+    @param addr_only - 1 if address only mapping
+    @param local_ip_address - local IP address
+    @param external_ip_address - external IP address
+    @param local_port - local port number
+    @param external_port - external port number
+    @param vfr_id - VRF ID
+*/
+define snat_add_static_mapping {
+  u32 client_index;
+  u32 context;
+  u8 is_add;
+  u8 is_ip4;
+  u8 addr_only;
+  u8 local_ip_address[16];
+  u8 external_ip_address[16];
+  u16 local_port;
+  u16 external_port;
+  u32 vrf_id;
+};
+
+/** \brief Add/delete S-NAT static mapping reply
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param retval - return code
+*/
+define snat_add_static_mapping_reply {
+  u32 context;
+  i32 retval;
+};
+
+/** \brief Dump S-NAT static mappings
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+*/
+define snat_static_mapping_dump {
+  u32 client_index;
+  u32 context;
+};
+
+/** \brief S-NAT static mapping details response
+    @param context - sender context, to match reply w/ request
+    @param is_ip4 - 1 if address type is IPv4
+    @param addr_only - 1 if address only mapping
+    @param local_ip_address - local IP address
+    @param external_ip_address - external IP address
+    @param local_port - local port number
+    @param external_port - external port number
+    @param vfr_id - VRF ID
+*/
+define snat_static_mapping_details {
+  u32 context;
+  u8 is_ip4;
+  u8 addr_only;
+  u8 local_ip_address[16];
+  u8 external_ip_address[16];
+  u16 local_port;
+  u16 external_port;
+  u32 vrf_id;
+};
+
+/** \brief Control ping from client to api server request
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+*/
+define snat_control_ping
+{
+  u32 client_index;
+  u32 context;
+};
+
+/** \brief Control ping from the client to the server response
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param retval - return code for the request
+    @param vpe_pid - the pid of the vpe, returned by the server
+*/
+define snat_control_ping_reply
+{
+  u32 context;
+  i32 retval;
+  u32 client_index;
+  u32 vpe_pid;
+};
+
+/** \brief Show S-NAT plugin startup config
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+*/
+define snat_show_config
+{
+  u32 client_index;
+  u32 context;
+};
+
+/** \brief Show S-NAT plugin startup config reply
+    @param context - sender context, to match reply w/ request
+    @param retval - return code for the request
+    @param static_mapping_only - if 1 dynamic translations disabled
+    @param static_mapping_connection_tracking - if 1 create session data
+    @param translation_buckets - number of translation hash buckets
+    @param translation_memory_size - translation hash memory size
+    @param user_buckets - number of user hash buckets
+    @param user_memory_size - user hash memory size
+    @param max_translations_per_user - maximum number of translations per user
+    @param outside_vrf_id - outside VRF id
+    @param inside_vrf_id - default inside VRF id
+*/
+define snat_show_config_reply
+{
+  u32 context;
+  i32 retval;
+  u8 static_mapping_only;
+  u8 static_mapping_connection_tracking;
+  u32 translation_buckets;
+  u32 translation_memory_size;
+  u32 user_buckets;
+  u32 user_memory_size;
+  u32 max_translations_per_user;
+  u32 outside_vrf_id;
+  u32 inside_vrf_id;
+};
+
+/** \brief Set S-NAT workers
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param worker_mask - S-NAT workers mask
+*/
+define snat_set_workers {
+  u32 client_index;
+  u32 context;
+  u64 worker_mask;
+};
+
+/** \brief Set S-NAT workers reply
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param retval - return code
+*/
+define snat_set_workers_reply {
+  u32 context;
+  i32 retval;
+};
+
+/** \brief Dump S-NAT workers
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+*/
+define snat_worker_dump {
+  u32 client_index;
+  u32 context;
+};
+
+/** \brief S-NAT workers details response
+    @param context - sender context, to match reply w/ request
+    @param worker_index - worker index
+    @param lcore_id - lcore ID
+    @param name - worker name
+*/
+define snat_worker_details {
+  u32 context;
+  u32 worker_index;
+  u32 lcore_id;
+  u8 name[64];
+};
diff --git a/src/plugins/snat/snat.c b/src/plugins/snat/snat.c
new file mode 100644
index 00000000000..bc9956841d2
--- /dev/null
+++ b/src/plugins/snat/snat.c
@@ -0,0 +1,1957 @@
+/*
+ * snat.c - simple nat plugin
+ *
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vnet/vnet.h>
+#include <vnet/plugin/plugin.h>
+#include <vlibapi/api.h>
+#include <snat/snat.h>
+
+#include <vlibapi/api.h>
+#include <vlibmemory/api.h>
+#include <vlibsocket/api.h>
+
+snat_main_t snat_main;
+
+/* define message IDs */
+#include <snat/snat_msg_enum.h>
+
+/* define message structures */
+#define vl_typedefs
+#include <snat/snat_all_api_h.h> 
+#undef vl_typedefs
+
+/* define generated endian-swappers */
+#define vl_endianfun
+#include <snat/snat_all_api_h.h> 
+#undef vl_endianfun
+
+#define vl_print(handle, ...) vlib_cli_output (handle, __VA_ARGS__)
+
+/* Get the API version number */
+#define vl_api_version(n,v) static u32 api_version=(v);
+#include <snat/snat_all_api_h.h>
+#undef vl_api_version
+
+/* Macro to finish up custom dump fns */
+#define FINISH                                  \
+    vec_add1 (s, 0);                            \
+    vl_print (handle, (char *)s);               \
+    vec_free (s);                               \
+    return handle;
+
+/* 
+ * A handy macro to set up a message reply.
+ * Assumes that the following variables are available:
+ * mp - pointer to request message
+ * rmp - pointer to reply message type
+ * rv - return value
+ */
+
+#define REPLY_MACRO(t)                                          \
+do {                                                            \
+    unix_shared_memory_queue_t * q =                            \
+    vl_api_client_index_to_input_queue (mp->client_index);      \
+    if (!q)                                                     \
+        return;                                                 \
+                                                                \
+    rmp = vl_msg_api_alloc (sizeof (*rmp));                     \
+    rmp->_vl_msg_id = ntohs((t)+sm->msg_id_base);               \
+    rmp->context = mp->context;                                 \
+    rmp->retval = ntohl(rv);                                    \
+                                                                \
+    vl_msg_api_send_shmem (q, (u8 *)&rmp);                      \
+} while(0);
+
+#define REPLY_MACRO2(t, body)                                   \
+do {                                                            \
+    unix_shared_memory_queue_t * q =                            \
+    vl_api_client_index_to_input_queue (mp->client_index);      \
+    if (!q)                                                     \
+        return;                                                 \
+                                                                \
+    rmp = vl_msg_api_alloc (sizeof (*rmp));                     \
+    rmp->_vl_msg_id = ntohs((t)+sm->msg_id_base);               \
+    rmp->context = mp->context;                                 \
+    rmp->retval = ntohl(rv);                                    \
+    do {body;} while (0);                                       \
+    vl_msg_api_send_shmem (q, (u8 *)&rmp);                      \
+} while(0);
+
+
+/* Hook up input features */
+VNET_FEATURE_INIT (ip4_snat_in2out, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "snat-in2out",
+  .runs_before = VNET_FEATURES ("snat-out2in"),
+};
+VNET_FEATURE_INIT (ip4_snat_out2in, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "snat-out2in",
+  .runs_before = VNET_FEATURES ("ip4-lookup"),
+};
+VNET_FEATURE_INIT (ip4_snat_in2out_worker_handoff, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "snat-in2out-worker-handoff",
+  .runs_before = VNET_FEATURES ("snat-out2in-worker-handoff"),
+};
+VNET_FEATURE_INIT (ip4_snat_out2in_worker_handoff, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "snat-out2in-worker-handoff",
+  .runs_before = VNET_FEATURES ("ip4-lookup"),
+};
+VNET_FEATURE_INIT (ip4_snat_in2out_fast, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "snat-in2out-fast",
+  .runs_before = VNET_FEATURES ("snat-out2in-fast"),
+};
+VNET_FEATURE_INIT (ip4_snat_out2in_fast, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "snat-out2in-fast",
+  .runs_before = VNET_FEATURES ("ip4-lookup"),
+};
+
+
+/* 
+ * This routine exists to convince the vlib plugin framework that
+ * we haven't accidentally copied a random .dll into the plugin directory.
+ *
+ * Also collects global variable pointers passed from the vpp engine
+ */
+
+clib_error_t * 
+vlib_plugin_register (vlib_main_t * vm, vnet_plugin_handoff_t * h,
+                      int from_early_init)
+{
+  snat_main_t * sm = &snat_main;
+  clib_error_t * error = 0;
+
+  sm->vlib_main = vm;
+  sm->vnet_main = h->vnet_main;
+  sm->ethernet_main = h->ethernet_main;
+
+  return error;
+}
+
+/*$$$$$ move to an installed header file */
+#if (1 || CLIB_DEBUG > 0)       /* "trust, but verify" */
+
+#define VALIDATE_SW_IF_INDEX(mp)				\
+ do { u32 __sw_if_index = ntohl(mp->sw_if_index);		\
+    vnet_main_t *__vnm = vnet_get_main();                       \
+    if (pool_is_free_index(__vnm->interface_main.sw_interfaces, \
+                           __sw_if_index)) {                    \
+        rv = VNET_API_ERROR_INVALID_SW_IF_INDEX;                \
+        goto bad_sw_if_index;                                   \
+    }                                                           \
+} while(0);
+
+#define BAD_SW_IF_INDEX_LABEL                   \
+do {                                            \
+bad_sw_if_index:                                \
+    ;                                           \
+} while (0);
+
+#define VALIDATE_RX_SW_IF_INDEX(mp)				\
+ do { u32 __rx_sw_if_index = ntohl(mp->rx_sw_if_index);		\
+    vnet_main_t *__vnm = vnet_get_main();                       \
+    if (pool_is_free_index(__vnm->interface_main.sw_interfaces, \
+                           __rx_sw_if_index)) {			\
+        rv = VNET_API_ERROR_INVALID_SW_IF_INDEX;                \
+        goto bad_rx_sw_if_index;				\
+    }                                                           \
+} while(0);
+
+#define BAD_RX_SW_IF_INDEX_LABEL		\
+do {                                            \
+bad_rx_sw_if_index:				\
+    ;                                           \
+} while (0);
+
+#define VALIDATE_TX_SW_IF_INDEX(mp)				\
+ do { u32 __tx_sw_if_index = ntohl(mp->tx_sw_if_index);		\
+    vnet_main_t *__vnm = vnet_get_main();                       \
+    if (pool_is_free_index(__vnm->interface_main.sw_interfaces, \
+                           __tx_sw_if_index)) {			\
+        rv = VNET_API_ERROR_INVALID_SW_IF_INDEX;                \
+        goto bad_tx_sw_if_index;				\
+    }                                                           \
+} while(0);
+
+#define BAD_TX_SW_IF_INDEX_LABEL		\
+do {                                            \
+bad_tx_sw_if_index:				\
+    ;                                           \
+} while (0);
+
+#else
+
+#define VALIDATE_SW_IF_INDEX(mp)
+#define BAD_SW_IF_INDEX_LABEL
+#define VALIDATE_RX_SW_IF_INDEX(mp)
+#define BAD_RX_SW_IF_INDEX_LABEL
+#define VALIDATE_TX_SW_IF_INDEX(mp)
+#define BAD_TX_SW_IF_INDEX_LABEL
+
+#endif  /* CLIB_DEBUG > 0 */
+
+void snat_add_address (snat_main_t *sm, ip4_address_t *addr)
+{
+  snat_address_t * ap;
+
+  /* Check if address already exists */
+  vec_foreach (ap, sm->addresses)
+    {
+      if (ap->addr.as_u32 == addr->as_u32)
+        return;
+    }
+
+  vec_add2 (sm->addresses, ap, 1);
+  ap->addr = *addr;
+  clib_bitmap_alloc (ap->busy_port_bitmap, 65535);
+}
+
+static int is_snat_address_used_in_static_mapping (snat_main_t *sm,
+                                                   ip4_address_t addr)
+{
+  snat_static_mapping_t *m;
+  pool_foreach (m, sm->static_mappings,
+  ({
+      if (m->external_addr.as_u32 == addr.as_u32)
+        return 1;
+  }));
+
+  return 0;
+}
+
+int snat_del_address (snat_main_t *sm, ip4_address_t addr)
+{
+  snat_address_t *a = 0;
+  snat_session_t *ses;
+  u32 *ses_to_be_removed = 0, *ses_index;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_user_key_t user_key;
+  snat_user_t *u;
+  snat_main_per_thread_data_t *tsm;
+
+  int i;
+
+  /* Find SNAT address */
+  for (i=0; i < vec_len (sm->addresses); i++)
+    {
+      if (sm->addresses[i].addr.as_u32 == addr.as_u32)
+        {
+          a = sm->addresses + i;
+          break;
+        }
+    }
+  if (!a)
+    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+  /* Check if address is used in some static mapping */
+  if (is_snat_address_used_in_static_mapping(sm, addr))
+    {
+      clib_warning ("address used in static mapping");
+      return VNET_API_ERROR_UNSPECIFIED;
+    }
+
+  /* Delete sessions using address */
+  if (a->busy_ports)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+        {
+          pool_foreach (ses, tsm->sessions, ({
+            if (ses->out2in.addr.as_u32 == addr.as_u32)
+              {
+                vec_add1 (ses_to_be_removed, ses - tsm->sessions);
+                kv.key = ses->in2out.as_u64;
+                clib_bihash_add_del_8_8 (&sm->in2out, &kv, 0);
+                kv.key = ses->out2in.as_u64;
+                clib_bihash_add_del_8_8 (&sm->out2in, &kv, 0);
+                clib_dlist_remove (tsm->list_pool, ses->per_user_index);
+                user_key.addr = ses->in2out.addr;
+                user_key.fib_index = ses->in2out.fib_index;
+                kv.key = user_key.as_u64;
+                if (!clib_bihash_search_8_8 (&sm->user_hash, &kv, &value))
+                  {
+                    u = pool_elt_at_index (tsm->users, value.value);
+                    u->nsessions--;
+                  }
+              }
+          }));
+
+          vec_foreach (ses_index, ses_to_be_removed)
+            pool_put_index (tsm->sessions, ses_index[0]);
+
+          vec_free (ses_to_be_removed);
+       }
+    }
+
+  vec_del1 (sm->addresses, i);
+
+  return 0;
+}
+
+static void increment_v4_address (ip4_address_t * a)
+{
+  u32 v;
+  
+  v = clib_net_to_host_u32(a->as_u32) + 1;
+  a->as_u32 = clib_host_to_net_u32(v);
+}
+
+/**
+ * @brief Add static mapping.
+ *
+ * Create static mapping between local addr+port and external addr+port.
+ *
+ * @param l_addr Local IPv4 address.
+ * @param e_addr External IPv4 address.
+ * @param l_port Local port number.
+ * @param e_port External port number.
+ * @param vrf_id VRF ID.
+ * @param addr_only If 0 address port and pair mapping, otherwise address only.
+ * @param is_add If 0 delete static mapping, otherwise add.
+ *
+ * @returns
+ */
+int snat_add_static_mapping(ip4_address_t l_addr, ip4_address_t e_addr,
+                            u16 l_port, u16 e_port, u32 vrf_id, int addr_only,
+                            int is_add)
+{
+  snat_main_t * sm = &snat_main;
+  snat_static_mapping_t *m;
+  snat_static_mapping_key_t m_key;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_address_t *a = 0;
+  u32 fib_index = ~0;
+  uword * p;
+  int i;
+
+  /* If outside FIB index is not resolved yet */
+  if (sm->outside_fib_index == ~0)
+    {
+      p = hash_get (sm->ip4_main->fib_index_by_table_id, sm->outside_vrf_id);
+      if (!p)
+        return VNET_API_ERROR_NO_SUCH_FIB;
+      sm->outside_fib_index = p[0];
+    }
+
+  m_key.addr = e_addr;
+  m_key.port = addr_only ? 0 : e_port;
+  m_key.fib_index = sm->outside_fib_index;
+  kv.key = m_key.as_u64;
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    m = 0;
+  else
+    m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (is_add)
+    {
+      if (m)
+        return VNET_API_ERROR_VALUE_EXIST;
+
+      /* Convert VRF id to FIB index */
+      if (vrf_id != ~0)
+        {
+          p = hash_get (sm->ip4_main->fib_index_by_table_id, vrf_id);
+          if (!p)
+            return VNET_API_ERROR_NO_SUCH_FIB;
+          fib_index = p[0];
+        }
+      /* If not specified use inside VRF id from SNAT plugin startup config */
+      else
+        {
+          if (sm->inside_fib_index == ~0)
+            {
+              p = hash_get (sm->ip4_main->fib_index_by_table_id, sm->inside_vrf_id);
+              if (!p)
+                return VNET_API_ERROR_NO_SUCH_FIB;
+              fib_index = p[0];
+              sm->inside_fib_index = fib_index;
+            }
+          else
+            fib_index = sm->inside_fib_index;
+
+          vrf_id = sm->inside_vrf_id;
+        }
+
+      /* Find external address in allocated addresses and reserve port for
+         address and port pair mapping when dynamic translations enabled */
+      if (!addr_only && !(sm->static_mapping_only))
+        {
+          for (i = 0; i < vec_len (sm->addresses); i++)
+            {
+              if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+                {
+                  a = sm->addresses + i;
+                  /* External port must be unused */
+                  if (clib_bitmap_get_no_check (a->busy_port_bitmap, e_port))
+                    return VNET_API_ERROR_INVALID_VALUE;
+                  clib_bitmap_set_no_check (a->busy_port_bitmap, e_port, 1);
+                  if (e_port > 1024)
+                    a->busy_ports++;
+
+                  break;
+                }
+            }
+          /* External address must be allocated */
+          if (!a)
+            return VNET_API_ERROR_NO_SUCH_ENTRY;
+        }
+
+      pool_get (sm->static_mappings, m);
+      memset (m, 0, sizeof (*m));
+      m->local_addr = l_addr;
+      m->external_addr = e_addr;
+      m->addr_only = addr_only;
+      m->vrf_id = vrf_id;
+      m->fib_index = fib_index;
+      if (!addr_only)
+        {
+          m->local_port = l_port;
+          m->external_port = e_port;
+        }
+
+      m_key.addr = m->local_addr;
+      m_key.port = m->local_port;
+      m_key.fib_index = m->fib_index;
+      kv.key = m_key.as_u64;
+      kv.value = m - sm->static_mappings;
+      clib_bihash_add_del_8_8(&sm->static_mapping_by_local, &kv, 1);
+
+      m_key.addr = m->external_addr;
+      m_key.port = m->external_port;
+      m_key.fib_index = sm->outside_fib_index;
+      kv.key = m_key.as_u64;
+      kv.value = m - sm->static_mappings;
+      clib_bihash_add_del_8_8(&sm->static_mapping_by_external, &kv, 1);
+
+      /* Assign worker */
+      if (sm->workers)
+        {
+          snat_user_key_t w_key0;
+          snat_static_mapping_key_t w_key1;
+
+          w_key0.addr = m->local_addr;
+          w_key0.fib_index = m->fib_index;
+          kv.key = w_key0.as_u64;
+
+          if (clib_bihash_search_8_8 (&sm->worker_by_in, &kv, &value))
+            {
+              kv.value = sm->first_worker_index +
+                sm->workers[sm->next_worker++ % vec_len (sm->workers)];
+
+              clib_bihash_add_del_8_8 (&sm->worker_by_in, &kv, 1);
+            }
+          else
+            {
+              kv.value = value.value;
+            }
+
+          w_key1.addr = m->external_addr;
+          w_key1.port = clib_host_to_net_u16 (m->external_port);
+          w_key1.fib_index = sm->outside_fib_index;
+          kv.key = w_key1.as_u64;
+          clib_bihash_add_del_8_8 (&sm->worker_by_out, &kv, 1);
+        }
+    }
+  else
+    {
+      if (!m)
+        return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+      /* Free external address port */
+      if (!addr_only && !(sm->static_mapping_only))
+        {
+          for (i = 0; i < vec_len (sm->addresses); i++)
+            {
+              if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+                {
+                  a = sm->addresses + i;
+                  clib_bitmap_set_no_check (a->busy_port_bitmap, e_port, 0);
+                  a->busy_ports--;
+
+                  break;
+                }
+            }
+        }
+
+      m_key.addr = m->local_addr;
+      m_key.port = m->local_port;
+      m_key.fib_index = m->fib_index;
+      kv.key = m_key.as_u64;
+      clib_bihash_add_del_8_8(&sm->static_mapping_by_local, &kv, 0);
+
+      m_key.addr = m->external_addr;
+      m_key.port = m->external_port;
+      m_key.fib_index = sm->outside_fib_index;
+      kv.key = m_key.as_u64;
+      clib_bihash_add_del_8_8(&sm->static_mapping_by_external, &kv, 0);
+
+      /* Delete session(s) for static mapping if exist */
+      if (!(sm->static_mapping_only) ||
+          (sm->static_mapping_only && sm->static_mapping_connection_tracking))
+        {
+          snat_user_key_t u_key;
+          snat_user_t *u;
+          dlist_elt_t * head, * elt;
+          u32 elt_index, head_index, del_elt_index;
+          u32 ses_index;
+          u64 user_index;
+          snat_session_t * s;
+          snat_main_per_thread_data_t *tsm;
+
+          u_key.addr = m->local_addr;
+          u_key.fib_index = m->fib_index;
+          kv.key = u_key.as_u64;
+          if (!clib_bihash_search_8_8 (&sm->user_hash, &kv, &value))
+            {
+              user_index = value.value;
+              if (!clib_bihash_search_8_8 (&sm->worker_by_in, &kv, &value))
+                tsm = vec_elt_at_index (sm->per_thread_data, value.value);
+              else
+                tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+              u = pool_elt_at_index (tsm->users, user_index);
+              if (u->nstaticsessions)
+                {
+                  head_index = u->sessions_per_user_list_head_index;
+                  head = pool_elt_at_index (tsm->list_pool, head_index);
+                  elt_index = head->next;
+                  elt = pool_elt_at_index (tsm->list_pool, elt_index);
+                  ses_index = elt->value;
+                  while (ses_index != ~0)
+                    {
+                      s =  pool_elt_at_index (tsm->sessions, ses_index);
+                      del_elt_index = elt_index;
+                      elt_index = elt->next;
+                      elt = pool_elt_at_index (tsm->list_pool, elt_index);
+                      ses_index = elt->value;
+
+                      if (!addr_only)
+                        {
+                          if ((s->out2in.addr.as_u32 != e_addr.as_u32) &&
+                              (clib_net_to_host_u16 (s->out2in.port) != e_port))
+                            continue;
+                        }
+
+                      value.key = s->in2out.as_u64;
+                      clib_bihash_add_del_8_8 (&sm->in2out, &value, 0);
+                      value.key = s->out2in.as_u64;
+                      clib_bihash_add_del_8_8 (&sm->out2in, &value, 0);
+                      pool_put (tsm->sessions, s);
+
+                      clib_dlist_remove (tsm->list_pool, del_elt_index);
+                      pool_put_index (tsm->list_pool, del_elt_index);
+                      u->nstaticsessions--;
+
+                      if (!addr_only)
+                        break;
+                    }
+                  if (addr_only)
+                    {
+                      pool_put (tsm->users, u);
+                      clib_bihash_add_del_8_8 (&sm->user_hash, &kv, 0);
+                    }
+                }
+            }
+        }
+
+      /* Delete static mapping from pool */
+      pool_put (sm->static_mappings, m);
+    }
+
+  return 0;
+}
+
+static int snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del)
+{
+  snat_main_t *sm = &snat_main;
+  snat_interface_t *i;
+  const char * feature_name;
+
+  if (sm->static_mapping_only && !(sm->static_mapping_connection_tracking))
+    feature_name = is_inside ?  "snat-in2out-fast" : "snat-out2in-fast";
+  else
+    {
+      if (sm->num_workers > 1)
+        feature_name = is_inside ?  "snat-in2out-worker-handoff" : "snat-out2in-worker-handoff";
+      else
+        feature_name = is_inside ?  "snat-in2out" : "snat-out2in";
+    }
+
+  vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index,
+			       !is_del, 0, 0);
+
+  if (sm->fq_in2out_index == ~0)
+    sm->fq_in2out_index = vlib_frame_queue_main_init (snat_in2out_node.index, 0);
+
+  if (sm->fq_out2in_index == ~0)
+    sm->fq_out2in_index = vlib_frame_queue_main_init (snat_out2in_node.index, 0);
+
+  pool_foreach (i, sm->interfaces,
+  ({
+    if (i->sw_if_index == sw_if_index)
+      {
+        if (is_del)
+          pool_put (sm->interfaces, i);
+        else
+          return VNET_API_ERROR_VALUE_EXIST;
+
+        return 0;
+      }
+  }));
+
+  if (is_del)
+    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+  pool_get (sm->interfaces, i);
+  i->sw_if_index = sw_if_index;
+  i->is_inside = is_inside;
+
+  return 0;
+}
+
+static int snat_set_workers (uword * bitmap)
+{
+  snat_main_t *sm = &snat_main;
+  int i;
+
+  if (sm->num_workers < 2)
+    return VNET_API_ERROR_FEATURE_DISABLED;
+
+  if (clib_bitmap_last_set (bitmap) >= sm->num_workers)
+    return VNET_API_ERROR_INVALID_WORKER;
+
+  vec_free (sm->workers);
+  clib_bitmap_foreach (i, bitmap,
+    ({
+      vec_add1(sm->workers, i);
+    }));
+
+  return 0;
+}
+
+static void 
+vl_api_snat_add_address_range_t_handler
+(vl_api_snat_add_address_range_t * mp)
+{
+  snat_main_t * sm = &snat_main;
+  vl_api_snat_add_address_range_reply_t * rmp;
+  ip4_address_t this_addr;
+  u32 start_host_order, end_host_order;
+  int i, count;
+  int rv = 0;
+  u32 * tmp;
+
+  if (mp->is_ip4 != 1)
+    {
+      rv = VNET_API_ERROR_UNIMPLEMENTED;
+      goto send_reply;
+    }
+
+  if (sm->static_mapping_only)
+    {
+      rv = VNET_API_ERROR_FEATURE_DISABLED;
+      goto send_reply;
+    }
+
+  tmp = (u32 *) mp->first_ip_address;
+  start_host_order = clib_host_to_net_u32 (tmp[0]);
+  tmp = (u32 *) mp->last_ip_address;
+  end_host_order = clib_host_to_net_u32 (tmp[0]);
+
+  count = (end_host_order - start_host_order) + 1;
+
+  if (count > 1024)
+    clib_warning ("%U - %U, %d addresses...",
+                  format_ip4_address, mp->first_ip_address,
+                  format_ip4_address, mp->last_ip_address,
+                  count);
+  
+  memcpy (&this_addr.as_u8, mp->first_ip_address, 4);
+
+  for (i = 0; i < count; i++)
+    {
+      if (mp->is_add)
+        snat_add_address (sm, &this_addr);
+      else
+        rv = snat_del_address (sm, this_addr);
+
+      if (rv)
+        goto send_reply;
+
+      increment_v4_address (&this_addr);
+    }
+
+ send_reply:
+  REPLY_MACRO (VL_API_SNAT_ADD_ADDRESS_RANGE_REPLY);
+}
+
+static void *vl_api_snat_add_address_range_t_print
+(vl_api_snat_add_address_range_t *mp, void * handle)
+{
+  u8 * s;
+
+  s = format (0, "SCRIPT: snat_add_address_range ");
+  s = format (s, "%U ", format_ip4_address, mp->first_ip_address);
+  if (memcmp (mp->first_ip_address, mp->last_ip_address, 4))
+    {
+      s = format (s, " - %U ", format_ip4_address, mp->last_ip_address);
+    }
+  FINISH;
+}
+
+static void
+send_snat_address_details
+(snat_address_t * a, unix_shared_memory_queue_t * q, u32 context)
+{
+  vl_api_snat_address_details_t *rmp;
+  snat_main_t * sm = &snat_main;
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  memset (rmp, 0, sizeof (*rmp));
+  rmp->_vl_msg_id = ntohs (VL_API_SNAT_ADDRESS_DETAILS+sm->msg_id_base);
+  rmp->is_ip4 = 1;
+  clib_memcpy (rmp->ip_address, &(a->addr), 4);
+  rmp->context = context;
+
+  vl_msg_api_send_shmem (q, (u8 *) & rmp);
+}
+
+static void
+vl_api_snat_address_dump_t_handler
+(vl_api_snat_address_dump_t * mp)
+{
+  unix_shared_memory_queue_t *q;
+  snat_main_t * sm = &snat_main;
+  snat_address_t * a;
+
+  q = vl_api_client_index_to_input_queue (mp->client_index);
+  if (q == 0)
+    return;
+
+  vec_foreach (a, sm->addresses)
+    send_snat_address_details (a, q, mp->context);
+}
+
+static void *vl_api_snat_address_dump_t_print
+(vl_api_snat_address_dump_t *mp, void * handle)
+{
+  u8 *s;
+
+  s = format (0, "SCRIPT: snat_address_dump ");
+
+  FINISH;
+}
+
+static void
+vl_api_snat_interface_add_del_feature_t_handler
+(vl_api_snat_interface_add_del_feature_t * mp)
+{
+  snat_main_t * sm = &snat_main;
+  vl_api_snat_interface_add_del_feature_reply_t * rmp;
+  u8 is_del = mp->is_add == 0;
+  u32 sw_if_index = ntohl(mp->sw_if_index);
+  int rv = 0;
+
+  VALIDATE_SW_IF_INDEX(mp);
+
+  rv = snat_interface_add_del (sw_if_index, mp->is_inside, is_del);
+  
+  BAD_SW_IF_INDEX_LABEL;
+
+  REPLY_MACRO(VL_API_SNAT_INTERFACE_ADD_DEL_FEATURE_REPLY);
+}
+
+static void *vl_api_snat_interface_add_del_feature_t_print
+(vl_api_snat_interface_add_del_feature_t * mp, void *handle)
+{
+  u8 * s;
+
+  s = format (0, "SCRIPT: snat_interface_add_del_feature ");
+  s = format (s, "sw_if_index %d %s %s",
+              clib_host_to_net_u32(mp->sw_if_index),
+              mp->is_inside ? "in":"out",
+              mp->is_add ? "" : "del");
+
+  FINISH;
+}
+
+static void
+send_snat_interface_details
+(snat_interface_t * i, unix_shared_memory_queue_t * q, u32 context)
+{
+  vl_api_snat_interface_details_t *rmp;
+  snat_main_t * sm = &snat_main;
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  memset (rmp, 0, sizeof (*rmp));
+  rmp->_vl_msg_id = ntohs (VL_API_SNAT_INTERFACE_DETAILS+sm->msg_id_base);
+  rmp->sw_if_index = ntohl (i->sw_if_index);
+  rmp->is_inside = i->is_inside;
+  rmp->context = context;
+
+  vl_msg_api_send_shmem (q, (u8 *) & rmp);
+}
+
+static void
+vl_api_snat_interface_dump_t_handler
+(vl_api_snat_interface_dump_t * mp)
+{
+  unix_shared_memory_queue_t *q;
+  snat_main_t * sm = &snat_main;
+  snat_interface_t * i;
+
+  q = vl_api_client_index_to_input_queue (mp->client_index);
+  if (q == 0)
+    return;
+
+  pool_foreach (i, sm->interfaces,
+  ({
+    send_snat_interface_details(i, q, mp->context);
+  }));
+}
+
+static void *vl_api_snat_interface_dump_t_print
+(vl_api_snat_interface_dump_t *mp, void * handle)
+{
+  u8 *s;
+
+  s = format (0, "SCRIPT: snat_interface_dump ");
+
+  FINISH;
+}static void
+
+vl_api_snat_add_static_mapping_t_handler
+(vl_api_snat_add_static_mapping_t * mp)
+{
+  snat_main_t * sm = &snat_main;
+  vl_api_snat_add_static_mapping_reply_t * rmp;
+  ip4_address_t local_addr, external_addr;
+  u16 local_port = 0, external_port = 0;
+  u32 vrf_id;
+  int rv = 0;
+
+  if (mp->is_ip4 != 1)
+    {
+      rv = VNET_API_ERROR_UNIMPLEMENTED;
+      goto send_reply;
+    }
+
+  memcpy (&local_addr.as_u8, mp->local_ip_address, 4);
+  memcpy (&external_addr.as_u8, mp->external_ip_address, 4);
+  if (mp->addr_only == 0)
+    {
+      local_port = clib_net_to_host_u16 (mp->local_port);
+      external_port = clib_net_to_host_u16 (mp->external_port);
+    }
+  vrf_id = clib_net_to_host_u32 (mp->vrf_id);
+
+  rv = snat_add_static_mapping(local_addr, external_addr, local_port,
+                               external_port, vrf_id, mp->addr_only,
+                               mp->is_add);
+
+ send_reply:
+  REPLY_MACRO (VL_API_SNAT_ADD_ADDRESS_RANGE_REPLY);
+}
+
+static void *vl_api_snat_add_static_mapping_t_print
+(vl_api_snat_add_static_mapping_t *mp, void * handle)
+{
+  u8 * s;
+
+  s = format (0, "SCRIPT: snat_add_static_mapping ");
+  s = format (s, "local_addr %U external_addr %U ",
+              format_ip4_address, mp->local_ip_address,
+              format_ip4_address, mp->external_ip_address);
+
+  if (mp->addr_only == 0)
+    s = format (s, "local_port %d external_port %d ",
+                clib_net_to_host_u16 (mp->local_port),
+                clib_net_to_host_u16 (mp->external_port));
+
+  if (mp->vrf_id != ~0)
+    s = format (s, "vrf %d", clib_net_to_host_u32 (mp->vrf_id));
+
+  FINISH;
+}
+
+static void
+send_snat_static_mapping_details
+(snat_static_mapping_t * m, unix_shared_memory_queue_t * q, u32 context)
+{
+  vl_api_snat_static_mapping_details_t *rmp;
+  snat_main_t * sm = &snat_main;
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  memset (rmp, 0, sizeof (*rmp));
+  rmp->_vl_msg_id = ntohs (VL_API_SNAT_STATIC_MAPPING_DETAILS+sm->msg_id_base);
+  rmp->is_ip4 = 1;
+  rmp->addr_only = m->addr_only;
+  clib_memcpy (rmp->local_ip_address, &(m->local_addr), 4);
+  clib_memcpy (rmp->external_ip_address, &(m->external_addr), 4);
+  rmp->local_port = htons (m->local_port);
+  rmp->external_port = htons (m->external_port);
+  rmp->vrf_id = htonl (m->vrf_id);
+  rmp->context = context;
+
+  vl_msg_api_send_shmem (q, (u8 *) & rmp);
+}
+
+static void
+vl_api_snat_static_mapping_dump_t_handler
+(vl_api_snat_static_mapping_dump_t * mp)
+{
+  unix_shared_memory_queue_t *q;
+  snat_main_t * sm = &snat_main;
+  snat_static_mapping_t * m;
+
+  q = vl_api_client_index_to_input_queue (mp->client_index);
+  if (q == 0)
+    return;
+
+  pool_foreach (m, sm->static_mappings,
+  ({
+      send_snat_static_mapping_details (m, q, mp->context);
+  }));
+}
+
+static void *vl_api_snat_static_mapping_dump_t_print
+(vl_api_snat_static_mapping_dump_t *mp, void * handle)
+{
+  u8 *s;
+
+  s = format (0, "SCRIPT: snat_static_mapping_dump ");
+
+  FINISH;
+}
+
+static void
+vl_api_snat_control_ping_t_handler
+(vl_api_snat_control_ping_t * mp)
+{
+  vl_api_snat_control_ping_reply_t *rmp;
+  snat_main_t * sm = &snat_main;
+  int rv = 0;
+
+  REPLY_MACRO2(VL_API_SNAT_CONTROL_PING_REPLY,
+  ({
+    rmp->vpe_pid = ntohl (getpid());
+  }));
+}
+
+static void *vl_api_snat_control_ping_t_print
+(vl_api_snat_control_ping_t *mp, void * handle)
+{
+  u8 *s;
+
+  s = format (0, "SCRIPT: snat_control_ping ");
+
+  FINISH;
+}
+
+static void
+vl_api_snat_show_config_t_handler
+(vl_api_snat_show_config_t * mp)
+{
+  vl_api_snat_show_config_reply_t *rmp;
+  snat_main_t * sm = &snat_main;
+  int rv = 0;
+
+  REPLY_MACRO2(VL_API_SNAT_SHOW_CONFIG_REPLY,
+  ({
+    rmp->translation_buckets = htonl (sm->translation_buckets);
+    rmp->translation_memory_size = htonl (sm->translation_memory_size);
+    rmp->user_buckets = htonl (sm->user_buckets);
+    rmp->user_memory_size = htonl (sm->user_memory_size);
+    rmp->max_translations_per_user = htonl (sm->max_translations_per_user);
+    rmp->outside_vrf_id = htonl (sm->outside_vrf_id);
+    rmp->inside_vrf_id = htonl (sm->inside_vrf_id);
+    rmp->static_mapping_only = sm->static_mapping_only;
+    rmp->static_mapping_connection_tracking =
+      sm->static_mapping_connection_tracking;
+  }));
+}
+
+static void *vl_api_snat_show_config_t_print
+(vl_api_snat_show_config_t *mp, void * handle)
+{
+  u8 *s;
+
+  s = format (0, "SCRIPT: snat_show_config ");
+
+  FINISH;
+}
+
+static void 
+vl_api_snat_set_workers_t_handler
+(vl_api_snat_set_workers_t * mp)
+{
+  snat_main_t * sm = &snat_main;
+  vl_api_snat_set_workers_reply_t * rmp;
+  int rv = 0;
+  uword *bitmap = 0;
+  u64 mask = clib_net_to_host_u64 (mp->worker_mask);
+
+  if (sm->num_workers < 2)
+    {
+      rv = VNET_API_ERROR_FEATURE_DISABLED;
+      goto send_reply;
+    }
+
+  bitmap = clib_bitmap_set_multiple (bitmap, 0, mask, BITS (mask)); 
+  rv = snat_set_workers(bitmap);
+  clib_bitmap_free (bitmap);
+
+ send_reply:
+  REPLY_MACRO (VL_API_SNAT_SET_WORKERS_REPLY);
+}
+
+static void *vl_api_snat_set_workers_t_print
+(vl_api_snat_set_workers_t *mp, void * handle)
+{
+  u8 * s;
+  uword *bitmap = 0;
+  u8 first = 1;
+  int i;
+  u64 mask = clib_net_to_host_u64 (mp->worker_mask);
+
+  s = format (0, "SCRIPT: snat_set_workers ");
+  bitmap = clib_bitmap_set_multiple (bitmap, 0, mask, BITS (mask)); 
+  clib_bitmap_foreach (i, bitmap,
+    ({
+      if (first)
+        s = format (s, "%d", i);
+      else
+        s = format (s, ",%d", i);
+      first = 0;
+    }));
+  clib_bitmap_free (bitmap);
+  FINISH;
+}
+
+static void
+send_snat_worker_details
+(u32 worker_index, unix_shared_memory_queue_t * q, u32 context)
+{
+  vl_api_snat_worker_details_t *rmp;
+  snat_main_t * sm = &snat_main;
+  vlib_worker_thread_t *w =
+    vlib_worker_threads + worker_index + sm->first_worker_index;
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  memset (rmp, 0, sizeof (*rmp));
+  rmp->_vl_msg_id = ntohs (VL_API_SNAT_WORKER_DETAILS+sm->msg_id_base);
+  rmp->context = context;
+  rmp->worker_index = htonl (worker_index);
+  rmp->lcore_id = htonl (w->lcore_id);
+  strncpy ((char *) rmp->name, (char *) w->name, ARRAY_LEN (rmp->name) - 1);
+
+  vl_msg_api_send_shmem (q, (u8 *) & rmp);
+}
+
+static void
+vl_api_snat_worker_dump_t_handler
+(vl_api_snat_worker_dump_t * mp)
+{
+  unix_shared_memory_queue_t *q;
+  snat_main_t * sm = &snat_main;
+  u32 * worker_index;
+
+  q = vl_api_client_index_to_input_queue (mp->client_index);
+  if (q == 0)
+    return;
+
+  vec_foreach (worker_index, sm->workers)
+    {
+      send_snat_worker_details(*worker_index, q, mp->context);
+    }
+}
+
+static void *vl_api_snat_worker_dump_t_print
+(vl_api_snat_worker_dump_t *mp, void * handle)
+{
+  u8 *s;
+
+  s = format (0, "SCRIPT: snat_worker_dump ");
+
+  FINISH;
+}
+
+/* List of message types that this plugin understands */
+#define foreach_snat_plugin_api_msg                                     \
+_(SNAT_ADD_ADDRESS_RANGE, snat_add_address_range)                       \
+_(SNAT_INTERFACE_ADD_DEL_FEATURE, snat_interface_add_del_feature)       \
+_(SNAT_ADD_STATIC_MAPPING, snat_add_static_mapping)                     \
+_(SNAT_CONTROL_PING, snat_control_ping)                                 \
+_(SNAT_STATIC_MAPPING_DUMP, snat_static_mapping_dump)                   \
+_(SNAT_SHOW_CONFIG, snat_show_config)                                   \
+_(SNAT_ADDRESS_DUMP, snat_address_dump)                                 \
+_(SNAT_INTERFACE_DUMP, snat_interface_dump)                             \
+_(SNAT_SET_WORKERS, snat_set_workers)                                   \
+_(SNAT_WORKER_DUMP, snat_worker_dump)
+
+/* Set up the API message handling tables */
+static clib_error_t *
+snat_plugin_api_hookup (vlib_main_t *vm)
+{
+   snat_main_t * sm __attribute__ ((unused)) = &snat_main;
+#define _(N,n)                                                  \
+    vl_msg_api_set_handlers((VL_API_##N + sm->msg_id_base),     \
+                           #n,					\
+                           vl_api_##n##_t_handler,              \
+                           vl_noop_handler,                     \
+                           vl_api_##n##_t_endian,               \
+                           vl_api_##n##_t_print,                \
+                           sizeof(vl_api_##n##_t), 1); 
+    foreach_snat_plugin_api_msg;
+#undef _
+
+    return 0;
+}
+
+#define vl_msg_name_crc_list
+#include <snat/snat_all_api_h.h>
+#undef vl_msg_name_crc_list
+
+static void
+setup_message_id_table (snat_main_t * sm, api_main_t * am)
+{
+#define _(id,n,crc) \
+  vl_msg_api_add_msg_name_crc (am, #n "_" #crc, id + sm->msg_id_base);
+  foreach_vl_msg_name_crc_snat;
+#undef _
+}
+
+static void plugin_custom_dump_configure (snat_main_t * sm) 
+{
+#define _(n,f) sm->api_main->msg_print_handlers \
+  [VL_API_##n + sm->msg_id_base]                \
+    = (void *) vl_api_##f##_t_print;
+  foreach_snat_plugin_api_msg;
+#undef _
+}
+
+static clib_error_t * snat_init (vlib_main_t * vm)
+{
+  snat_main_t * sm = &snat_main;
+  clib_error_t * error = 0;
+  ip4_main_t * im = &ip4_main;
+  ip_lookup_main_t * lm = &im->lookup_main;
+  u8 * name;
+  uword *p;
+  vlib_thread_registration_t *tr;
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+  uword *bitmap = 0;
+  u32 i;
+
+  name = format (0, "snat_%08x%c", api_version, 0);
+
+  /* Ask for a correctly-sized block of API message decode slots */
+  sm->msg_id_base = vl_msg_api_get_msg_ids 
+      ((char *) name, VL_MSG_FIRST_AVAILABLE);
+
+  sm->vlib_main = vm;
+  sm->vnet_main = vnet_get_main();
+  sm->ip4_main = im;
+  sm->ip4_lookup_main = lm;
+  sm->api_main = &api_main;
+  sm->first_worker_index = 0;
+  sm->next_worker = 0;
+  sm->num_workers = 0;
+  sm->workers = 0;
+  sm->fq_in2out_index = ~0;
+  sm->fq_out2in_index = ~0;
+
+  p = hash_get_mem (tm->thread_registrations_by_name, "workers");
+  if (p)
+    {
+      tr = (vlib_thread_registration_t *) p[0];
+      if (tr)
+        {
+          sm->num_workers = tr->count;
+          sm->first_worker_index = tr->first_index;
+        }
+    }
+
+  /* Use all available workers by default */
+  if (sm->num_workers > 1)
+    {
+      for (i=0; i < sm->num_workers; i++)
+        bitmap = clib_bitmap_set (bitmap, i, 1);
+      snat_set_workers(bitmap);
+      clib_bitmap_free (bitmap);
+    }
+
+  error = snat_plugin_api_hookup (vm);
+
+  /* Add our API messages to the global name_crc hash table */
+  setup_message_id_table (sm, &api_main);
+
+  plugin_custom_dump_configure (sm);
+  vec_free(name);
+
+  return error;
+}
+
+VLIB_INIT_FUNCTION (snat_init);
+
+void snat_free_outside_address_and_port (snat_main_t * sm, 
+                                         snat_session_key_t * k, 
+                                         u32 address_index)
+{
+  snat_address_t *a;
+  u16 port_host_byte_order = clib_net_to_host_u16 (k->port);
+  
+  ASSERT (address_index < vec_len (sm->addresses));
+
+  a = sm->addresses + address_index;
+
+  ASSERT (clib_bitmap_get_no_check (a->busy_port_bitmap,
+    port_host_byte_order) == 1);
+
+  clib_bitmap_set_no_check (a->busy_port_bitmap, port_host_byte_order, 0);
+  a->busy_ports--;
+}  
+
+/**
+ * @brief Match SNAT static mapping.
+ *
+ * @param sm          SNAT main.
+ * @param match       Address and port to match.
+ * @param mapping     External or local address and port of the matched mapping.
+ * @param by_external If 0 match by local address otherwise match by external
+ *                    address.
+ *
+ * @returns 0 if match found otherwise 1.
+ */
+int snat_static_mapping_match (snat_main_t * sm,
+                               snat_session_key_t match,
+                               snat_session_key_t * mapping,
+                               u8 by_external)
+{
+  clib_bihash_kv_8_8_t kv, value;
+  snat_static_mapping_t *m;
+  snat_static_mapping_key_t m_key;
+  clib_bihash_8_8_t *mapping_hash = &sm->static_mapping_by_local;
+
+  if (by_external)
+    mapping_hash = &sm->static_mapping_by_external;
+
+  m_key.addr = match.addr;
+  m_key.port = clib_net_to_host_u16 (match.port);
+  m_key.fib_index = match.fib_index;
+
+  kv.key = m_key.as_u64;
+
+  if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+    {
+      /* Try address only mapping */
+      m_key.port = 0;
+      kv.key = m_key.as_u64;
+      if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+        return 1;
+    }
+
+  m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (by_external)
+    {
+      mapping->addr = m->local_addr;
+      /* Address only mapping doesn't change port */
+      mapping->port = m->addr_only ? match.port
+        : clib_host_to_net_u16 (m->local_port);
+      mapping->fib_index = m->fib_index;
+    }
+  else
+    {
+      mapping->addr = m->external_addr;
+      /* Address only mapping doesn't change port */
+      mapping->port = m->addr_only ? match.port
+        : clib_host_to_net_u16 (m->external_port);
+      mapping->fib_index = sm->outside_fib_index;
+    }
+
+  return 0;
+}
+
+int snat_alloc_outside_address_and_port (snat_main_t * sm, 
+                                         snat_session_key_t * k,
+                                         u32 * address_indexp)
+{
+  int i;
+  snat_address_t *a;
+  u32 portnum;
+
+  for (i = 0; i < vec_len (sm->addresses); i++)
+    {
+      if (sm->addresses[i].busy_ports < (65535-1024))
+        {
+          a = sm->addresses + i;
+
+          while (1)
+            {
+              portnum = random_u32 (&sm->random_seed);
+              portnum &= 0xFFFF;
+              if (portnum < 1024)
+                continue;
+              if (clib_bitmap_get_no_check (a->busy_port_bitmap, portnum))
+                continue;
+              clib_bitmap_set_no_check (a->busy_port_bitmap, portnum, 1);
+              a->busy_ports++;
+              /* Caller sets protocol and fib index */
+              k->addr = a->addr;
+              k->port = clib_host_to_net_u16(portnum);
+              *address_indexp = i;
+              return 0;
+            }
+        }
+    }
+  /* Totally out of translations to use... */
+  return 1;
+}
+
+
+static clib_error_t *
+add_address_command_fn (vlib_main_t * vm,
+                        unformat_input_t * input,
+                        vlib_cli_command_t * cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  snat_main_t * sm = &snat_main;
+  ip4_address_t start_addr, end_addr, this_addr;
+  u32 start_host_order, end_host_order;
+  int i, count;
+  int is_add = 1;
+  int rv = 0;
+
+  /* Get a line of input. */
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "%U - %U",
+                    unformat_ip4_address, &start_addr,
+                    unformat_ip4_address, &end_addr))
+        ;
+      else if (unformat (line_input, "%U", unformat_ip4_address, &start_addr))
+        end_addr = start_addr;
+      else if (unformat (line_input, "del"))
+        is_add = 0;
+      else
+        return clib_error_return (0, "unknown input '%U'",
+          format_unformat_error, input);
+     }
+  unformat_free (line_input);
+
+  if (sm->static_mapping_only)
+    return clib_error_return (0, "static mapping only mode");
+
+  start_host_order = clib_host_to_net_u32 (start_addr.as_u32);
+  end_host_order = clib_host_to_net_u32 (end_addr.as_u32);
+  
+  if (end_host_order < start_host_order)
+    return clib_error_return (0, "end address less than start address");
+
+  count = (end_host_order - start_host_order) + 1;
+
+  if (count > 1024)
+    clib_warning ("%U - %U, %d addresses...",
+                  format_ip4_address, &start_addr,
+                  format_ip4_address, &end_addr,
+                  count);
+  
+  this_addr = start_addr;
+
+  for (i = 0; i < count; i++)
+    {
+      if (is_add)
+        snat_add_address (sm, &this_addr);
+      else
+        rv = snat_del_address (sm, this_addr);
+
+      switch (rv)
+        {
+        case VNET_API_ERROR_NO_SUCH_ENTRY:
+          return clib_error_return (0, "S-NAT address not exist.");
+          break;
+        case VNET_API_ERROR_UNSPECIFIED:
+          return clib_error_return (0, "S-NAT address used in static mapping.");
+          break;
+        default:
+          break;
+        }
+
+      increment_v4_address (&this_addr);
+    }
+
+  return 0;
+}
+
+VLIB_CLI_COMMAND (add_address_command, static) = {
+  .path = "snat add address",
+  .short_help = "snat add addresses <ip4-range-start> [- <ip4-range-end>] [del]",
+  .function = add_address_command_fn,
+};
+
+static clib_error_t *
+snat_feature_command_fn (vlib_main_t * vm,
+                          unformat_input_t * input,
+                          vlib_cli_command_t * cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  vnet_main_t * vnm = vnet_get_main();
+  clib_error_t * error = 0;
+  u32 sw_if_index;
+  u32 * inside_sw_if_indices = 0;
+  u32 * outside_sw_if_indices = 0;
+  int is_del = 0;
+  int i;
+
+  sw_if_index = ~0;
+
+  /* Get a line of input. */
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "in %U", unformat_vnet_sw_interface,
+                    vnm, &sw_if_index))
+        vec_add1 (inside_sw_if_indices, sw_if_index);
+      else if (unformat (line_input, "out %U", unformat_vnet_sw_interface,
+                         vnm, &sw_if_index))
+        vec_add1 (outside_sw_if_indices, sw_if_index);
+      else if (unformat (line_input, "del"))
+        is_del = 1;
+      else
+        return clib_error_return (0, "unknown input '%U'",
+          format_unformat_error, input);
+    }
+  unformat_free (line_input);
+
+  if (vec_len (inside_sw_if_indices))
+    {
+      for (i = 0; i < vec_len(inside_sw_if_indices); i++)
+        {
+          sw_if_index = inside_sw_if_indices[i];
+          snat_interface_add_del (sw_if_index, 1, is_del);
+        }
+    }
+
+  if (vec_len (outside_sw_if_indices))
+    {
+      for (i = 0; i < vec_len(outside_sw_if_indices); i++)
+        {
+          sw_if_index = outside_sw_if_indices[i];
+          snat_interface_add_del (sw_if_index, 0, is_del);
+        }
+    }
+
+  vec_free (inside_sw_if_indices);
+  vec_free (outside_sw_if_indices);
+
+  return error;
+}
+
+VLIB_CLI_COMMAND (set_interface_snat_command, static) = {
+  .path = "set interface snat",
+  .function = snat_feature_command_fn,
+  .short_help = "set interface snat in <intfc> out <intfc> [del]",
+};
+
+static clib_error_t *
+add_static_mapping_command_fn (vlib_main_t * vm,
+                               unformat_input_t * input,
+                               vlib_cli_command_t * cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  clib_error_t * error = 0;
+  ip4_address_t l_addr, e_addr;
+  u32 l_port = 0, e_port = 0, vrf_id = ~0;
+  int is_add = 1;
+  int addr_only = 1;
+  int rv;
+
+  /* Get a line of input. */
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "local %U %u", unformat_ip4_address, &l_addr,
+                    &l_port))
+        addr_only = 0;
+      else if (unformat (line_input, "local %U", unformat_ip4_address, &l_addr))
+        ;
+      else if (unformat (line_input, "external %U %u", unformat_ip4_address,
+                         &e_addr, &e_port))
+        addr_only = 0;
+      else if (unformat (line_input, "external %U", unformat_ip4_address,
+                         &e_addr))
+        ;
+      else if (unformat (line_input, "vrf %u", &vrf_id))
+        ;
+      else if (unformat (line_input, "del"))
+        is_add = 0;
+      else
+        return clib_error_return (0, "unknown input: '%U'",
+          format_unformat_error, line_input);
+    }
+  unformat_free (line_input);
+
+  rv = snat_add_static_mapping(l_addr, e_addr, (u16) l_port, (u16) e_port,
+                               vrf_id, addr_only, is_add);
+
+  switch (rv)
+    {
+    case VNET_API_ERROR_INVALID_VALUE:
+      return clib_error_return (0, "External port already in use.");
+      break;
+    case VNET_API_ERROR_NO_SUCH_ENTRY:
+      if (is_add)
+        return clib_error_return (0, "External addres must be allocated.");
+      else
+        return clib_error_return (0, "Mapping not exist.");
+      break;
+    case VNET_API_ERROR_NO_SUCH_FIB:
+      return clib_error_return (0, "No such VRF id.");
+    case VNET_API_ERROR_VALUE_EXIST:
+      return clib_error_return (0, "Mapping already exist.");
+    default:
+      break;
+    }
+
+  return error;
+}
+
+/*?
+ * @cliexpar
+ * @cliexstart{snat add static mapping}
+ * Static mapping allows hosts on the external network to initiate connection
+ * to to the local network host.
+ * To create static mapping between local host address 10.0.0.3 port 6303 and
+ * external address 4.4.4.4 port 3606 use:
+ *  vpp# snat add static mapping local 10.0.0.3 6303 external 4.4.4.4 3606
+ * If not runnig "static mapping only" S-NAT plugin mode use before:
+ *  vpp# snat add address 4.4.4.4
+ * To create static mapping between local and external address use:
+ *  vpp# snat add static mapping local 10.0.0.3 external 4.4.4.4
+ * @cliexend
+?*/
+VLIB_CLI_COMMAND (add_static_mapping_command, static) = {
+  .path = "snat add static mapping",
+  .function = add_static_mapping_command_fn,
+  .short_help =
+    "snat add static mapping local <addr> [<port>] external <addr> [<port>] [vrf <table-id>] [del]",
+};
+
+static clib_error_t *
+set_workers_command_fn (vlib_main_t * vm,
+                        unformat_input_t * input,
+                        vlib_cli_command_t * cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  uword *bitmap = 0;
+  int rv = 0;
+
+  /* Get a line of input. */
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "%U", unformat_bitmap_list, &bitmap))
+        ;
+      else
+        return clib_error_return (0, "unknown input '%U'",
+          format_unformat_error, input);
+     }
+  unformat_free (line_input);
+
+  if (bitmap == 0)
+    return clib_error_return (0, "List of workers must be specified.");
+
+  rv = snat_set_workers(bitmap);
+
+  clib_bitmap_free (bitmap);
+
+  switch (rv)
+    {
+    case VNET_API_ERROR_INVALID_WORKER:
+      return clib_error_return (0, "Invalid worker(s).");
+      break;
+    case VNET_API_ERROR_FEATURE_DISABLED:
+      return clib_error_return (0,
+        "Supported only if 2 or more workes available.");
+      break;
+    default:
+      break;
+    }
+
+  return 0;
+}
+
+/*?
+ * @cliexpar
+ * @cliexstart{set snat workers}
+ * Set SNAT workers if 2 or more workers available, use:
+ *  vpp# set snat workers 0-2,5
+ * @cliexend
+?*/
+VLIB_CLI_COMMAND (set_workers_command, static) = {
+  .path = "set snat workers",
+  .function = set_workers_command_fn,
+  .short_help =
+    "set snat workers <workers-list>",
+};
+
+static clib_error_t *
+snat_config (vlib_main_t * vm, unformat_input_t * input)
+{
+  snat_main_t * sm = &snat_main;
+  u32 translation_buckets = 1024;
+  u32 translation_memory_size = 128<<20;
+  u32 user_buckets = 128;
+  u32 user_memory_size = 64<<20;
+  u32 max_translations_per_user = 100;
+  u32 outside_vrf_id = 0;
+  u32 inside_vrf_id = 0;
+  u32 static_mapping_buckets = 1024;
+  u32 static_mapping_memory_size = 64<<20;
+  u8 static_mapping_only = 0;
+  u8 static_mapping_connection_tracking = 0;
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "translation hash buckets %d", &translation_buckets))
+        ;
+      else if (unformat (input, "translation hash memory %d",
+                         &translation_memory_size));
+      else if (unformat (input, "user hash buckets %d", &user_buckets))
+        ;
+      else if (unformat (input, "user hash memory %d",
+                         &user_memory_size))
+        ;
+      else if (unformat (input, "max translations per user %d",
+                         &max_translations_per_user))
+        ;
+      else if (unformat (input, "outside VRF id %d",
+                         &outside_vrf_id))
+        ;
+      else if (unformat (input, "inside VRF id %d",
+                         &inside_vrf_id))
+        ;
+      else if (unformat (input, "static mapping only"))
+        {
+          static_mapping_only = 1;
+          if (unformat (input, "connection tracking"))
+            static_mapping_connection_tracking = 1;
+        }
+      else 
+	return clib_error_return (0, "unknown input '%U'",
+				  format_unformat_error, input);
+    }
+
+  /* for show commands, etc. */
+  sm->translation_buckets = translation_buckets;
+  sm->translation_memory_size = translation_memory_size;
+  sm->user_buckets = user_buckets;
+  sm->user_memory_size = user_memory_size;
+  sm->max_translations_per_user = max_translations_per_user;
+  sm->outside_vrf_id = outside_vrf_id;
+  sm->outside_fib_index = ~0;
+  sm->inside_vrf_id = inside_vrf_id;
+  sm->inside_fib_index = ~0;
+  sm->static_mapping_only = static_mapping_only;
+  sm->static_mapping_connection_tracking = static_mapping_connection_tracking;
+
+  if (!static_mapping_only ||
+      (static_mapping_only && static_mapping_connection_tracking))
+    {
+      clib_bihash_init_8_8 (&sm->worker_by_in, "worker-by-in", user_buckets,
+                            user_memory_size);
+
+      clib_bihash_init_8_8 (&sm->worker_by_out, "worker-by-out", user_buckets,
+                            user_memory_size);
+
+      vec_validate (sm->per_thread_data, tm->n_vlib_mains - 1);
+
+      clib_bihash_init_8_8 (&sm->in2out, "in2out", translation_buckets,
+                            translation_memory_size);
+
+      clib_bihash_init_8_8 (&sm->out2in, "out2in", translation_buckets,
+                            translation_memory_size);
+
+      clib_bihash_init_8_8 (&sm->user_hash, "users", user_buckets,
+                            user_memory_size);
+    }
+  clib_bihash_init_8_8 (&sm->static_mapping_by_local,
+                        "static_mapping_by_local", static_mapping_buckets,
+                        static_mapping_memory_size);
+
+  clib_bihash_init_8_8 (&sm->static_mapping_by_external,
+                        "static_mapping_by_external", static_mapping_buckets,
+                        static_mapping_memory_size);
+  return 0;
+}
+
+VLIB_CONFIG_FUNCTION (snat_config, "snat");
+
+u8 * format_snat_key (u8 * s, va_list * args)
+{
+  snat_session_key_t * key = va_arg (*args, snat_session_key_t *);
+  char * protocol_string = "unknown";
+  static char *protocol_strings[] = {
+      "UDP",
+      "TCP",
+      "ICMP",
+  };
+
+  if (key->protocol < ARRAY_LEN(protocol_strings))
+      protocol_string = protocol_strings[key->protocol];
+
+  s = format (s, "%U proto %s port %d fib %d",
+              format_ip4_address, &key->addr, protocol_string,
+              clib_net_to_host_u16 (key->port), key->fib_index);
+  return s;
+}
+
+u8 * format_snat_session (u8 * s, va_list * args)
+{
+  snat_main_t * sm __attribute__((unused)) = va_arg (*args, snat_main_t *);
+  snat_session_t * sess = va_arg (*args, snat_session_t *);
+
+  s = format (s, "  i2o %U\n", format_snat_key, &sess->in2out);
+  s = format (s, "    o2i %U\n", format_snat_key, &sess->out2in);
+  s = format (s, "       last heard %.2f\n", sess->last_heard);
+  s = format (s, "       total pkts %d, total bytes %lld\n",
+              sess->total_pkts, sess->total_bytes);
+  if (snat_is_session_static (sess))
+    s = format (s, "       static translation\n");
+  else
+    s = format (s, "       dynamic translation\n");
+
+  return s;
+}
+
+u8 * format_snat_user (u8 * s, va_list * args)
+{
+  snat_main_per_thread_data_t * sm = va_arg (*args, snat_main_per_thread_data_t *);
+  snat_user_t * u = va_arg (*args, snat_user_t *);
+  int verbose = va_arg (*args, int);
+  dlist_elt_t * head, * elt;
+  u32 elt_index, head_index;
+  u32 session_index;
+  snat_session_t * sess;
+
+  s = format (s, "%U: %d dynamic translations, %d static translations\n",
+              format_ip4_address, &u->addr, u->nsessions, u->nstaticsessions);
+
+  if (verbose == 0)
+    return s;
+
+  if (u->nsessions || u->nstaticsessions)
+    {
+      head_index = u->sessions_per_user_list_head_index;
+      head = pool_elt_at_index (sm->list_pool, head_index);
+
+      elt_index = head->next;
+      elt = pool_elt_at_index (sm->list_pool, elt_index);
+      session_index = elt->value;
+
+      while (session_index != ~0)
+        {
+          sess = pool_elt_at_index (sm->sessions, session_index);
+
+          s = format (s, "  %U\n", format_snat_session, sm, sess);
+
+          elt_index = elt->next;
+          elt = pool_elt_at_index (sm->list_pool, elt_index);
+          session_index = elt->value;
+        }
+    }
+
+  return s;
+}
+
+u8 * format_snat_static_mapping (u8 * s, va_list * args)
+{
+  snat_static_mapping_t *m = va_arg (*args, snat_static_mapping_t *);
+
+  if (m->addr_only)
+      s = format (s, "local %U external %U vrf %d",
+                  format_ip4_address, &m->local_addr,
+                  format_ip4_address, &m->external_addr,
+                  m->vrf_id);
+  else
+      s = format (s, "local %U:%d external %U:%d vrf %d",
+                  format_ip4_address, &m->local_addr, m->local_port,
+                  format_ip4_address, &m->external_addr, m->external_port,
+                  m->vrf_id);
+
+  return s;
+}
+
+static clib_error_t *
+show_snat_command_fn (vlib_main_t * vm,
+		 unformat_input_t * input,
+		 vlib_cli_command_t * cmd)
+{
+  int verbose = 0;
+  snat_main_t * sm = &snat_main;
+  snat_user_t * u;
+  snat_static_mapping_t *m;
+  snat_interface_t *i;
+  snat_address_t * ap;
+  vnet_main_t *vnm = vnet_get_main();
+  snat_main_per_thread_data_t *tsm;
+  u32 users_num = 0, sessions_num = 0, *worker;
+  uword j = 0;
+
+  if (unformat (input, "detail"))
+    verbose = 1;
+  else if (unformat (input, "verbose"))
+    verbose = 2;
+
+  if (sm->static_mapping_only)
+    {
+      if (sm->static_mapping_connection_tracking)
+        vlib_cli_output (vm, "SNAT mode: static mapping only connection "
+                         "tracking");
+      else
+        vlib_cli_output (vm, "SNAT mode: static mapping only");
+    }
+  else
+    {
+      vlib_cli_output (vm, "SNAT mode: dynamic translations enabled");
+    }
+
+  if (verbose > 0)
+    {
+      pool_foreach (i, sm->interfaces,
+      ({
+        vlib_cli_output (vm, "%U %s", format_vnet_sw_interface_name, vnm,
+                         vnet_get_sw_interface (vnm, i->sw_if_index),
+                         i->is_inside ? "in" : "out");
+      }));
+
+      vec_foreach (ap, sm->addresses)
+        {
+          u8 * s = format (0, "");
+          vlib_cli_output (vm, "%U", format_ip4_address, &ap->addr);
+          clib_bitmap_foreach (j, ap->busy_port_bitmap,
+            ({
+              s = format (s, " %d", j);
+            }));
+          vlib_cli_output (vm, "  %d busy ports:%v", ap->busy_ports, s);
+        }
+    }
+
+  if (sm->num_workers > 1)
+    {
+      vlib_cli_output (vm, "%d workers", vec_len (sm->workers));
+      if (verbose > 0)
+        {
+          vec_foreach (worker, sm->workers)
+            {
+              vlib_worker_thread_t *w =
+                vlib_worker_threads + *worker + sm->first_worker_index;
+              vlib_cli_output (vm, "  %v", w->name);
+            }
+        }
+    }
+
+  if (sm->static_mapping_only && !(sm->static_mapping_connection_tracking))
+    {
+      vlib_cli_output (vm, "%d static mappings",
+                       pool_elts (sm->static_mappings));
+
+      if (verbose > 0)
+        {
+          pool_foreach (m, sm->static_mappings,
+          ({
+            vlib_cli_output (vm, "%U", format_snat_static_mapping, m);
+          }));
+        }
+    }
+  else
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+        {
+          users_num += pool_elts (tsm->users);
+          sessions_num += pool_elts (tsm->sessions);
+        }
+
+      vlib_cli_output (vm, "%d users, %d outside addresses, %d active sessions,"
+                       " %d static mappings",
+                       users_num,
+                       vec_len (sm->addresses),
+                       sessions_num,
+                       pool_elts (sm->static_mappings));
+
+      if (verbose > 0)
+        {
+          vlib_cli_output (vm, "%U", format_bihash_8_8, &sm->in2out,
+                           verbose - 1);
+          vlib_cli_output (vm, "%U", format_bihash_8_8, &sm->out2in,
+                           verbose - 1);
+          vlib_cli_output (vm, "%U", format_bihash_8_8, &sm->worker_by_in,
+                           verbose - 1);
+          vlib_cli_output (vm, "%U", format_bihash_8_8, &sm->worker_by_out,
+                           verbose - 1);
+          vec_foreach_index (j, sm->per_thread_data)
+            {
+              tsm = vec_elt_at_index (sm->per_thread_data, j);
+
+              if (pool_elts (tsm->users) == 0)
+                continue;
+
+              vlib_worker_thread_t *w = vlib_worker_threads + j;
+              vlib_cli_output (vm, "Thread %d (%v at lcore %u):", j, w->name,
+                               w->lcore_id);
+              vlib_cli_output (vm, "  %d list pool elements",
+                               pool_elts (tsm->list_pool));
+
+              pool_foreach (u, tsm->users,
+              ({
+                vlib_cli_output (vm, "  %U", format_snat_user, tsm, u,
+                                 verbose - 1);
+              }));
+            }
+
+          if (pool_elts (sm->static_mappings))
+            {
+              vlib_cli_output (vm, "static mappings:");
+              pool_foreach (m, sm->static_mappings,
+              ({
+                vlib_cli_output (vm, "%U", format_snat_static_mapping, m);
+              }));
+            }
+        }
+    }
+
+  return 0;
+}
+
+VLIB_CLI_COMMAND (show_snat_command, static) = {
+    .path = "show snat",
+    .short_help = "show snat",
+    .function = show_snat_command_fn,
+};
diff --git a/src/plugins/snat/snat.h b/src/plugins/snat/snat.h
new file mode 100644
index 00000000000..cb31dc51423
--- /dev/null
+++ b/src/plugins/snat/snat.h
@@ -0,0 +1,259 @@
+
+/*
+ * snat.h - simple nat definitions
+ *
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef __included_snat_h__
+#define __included_snat_h__
+
+#include <vnet/vnet.h>
+#include <vnet/ip/ip.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/ip/icmp46_packet.h>
+#include <vnet/api_errno.h>
+#include <vppinfra/bihash_8_8.h>
+#include <vppinfra/dlist.h>
+#include <vppinfra/error.h>
+#include <vlibapi/api.h>
+
+/* Key */
+typedef struct {
+  union 
+  {
+    struct 
+    {
+      ip4_address_t addr;
+      u16 port;
+      u16 protocol:3,
+        fib_index:13;
+    };
+    u64 as_u64;
+  };
+} snat_session_key_t;
+
+typedef struct {
+  union
+  {
+    struct
+    {
+      ip4_address_t addr;
+      u32 fib_index;
+    };
+    u64 as_u64;
+  };
+} snat_user_key_t;
+
+typedef struct {
+  union
+  {
+    struct
+    {
+      ip4_address_t addr;
+      u16 port;
+      u16 fib_index;
+    };
+    u64 as_u64;
+  };
+} snat_static_mapping_key_t;
+
+
+typedef enum {
+  SNAT_PROTOCOL_UDP = 0,
+  SNAT_PROTOCOL_TCP,
+  SNAT_PROTOCOL_ICMP,
+} snat_protocol_t;
+
+
+#define SNAT_SESSION_FLAG_STATIC_MAPPING 1
+
+typedef CLIB_PACKED(struct {
+  snat_session_key_t out2in;    /* 0-15 */
+
+  snat_session_key_t in2out;    /* 16-31 */
+
+  u32 flags;                    /* 32-35 */
+
+  /* per-user translations */
+  u32 per_user_index;           /* 36-39 */
+
+  u32 per_user_list_head_index; /* 40-43 */
+
+  /* Last heard timer */
+  f64 last_heard;               /* 44-51 */
+
+  u64 total_bytes;              /* 52-59 */
+  
+  u32 total_pkts;               /* 60-63 */
+
+  /* Outside address */
+  u32 outside_address_index;    /* 64-67 */
+
+}) snat_session_t;
+
+
+typedef struct {
+  ip4_address_t addr;
+  u32 sessions_per_user_list_head_index;
+  u32 nsessions;
+  u32 nstaticsessions;
+} snat_user_t;
+
+typedef struct {
+  ip4_address_t addr;
+  u32 busy_ports;
+  uword * busy_port_bitmap;
+} snat_address_t;
+
+typedef struct {
+  ip4_address_t local_addr;
+  ip4_address_t external_addr;
+  u16 local_port;
+  u16 external_port;
+  u8 addr_only;
+  u32 vrf_id;
+  u32 fib_index;
+} snat_static_mapping_t;
+
+typedef struct {
+  u32 sw_if_index;
+  u8 is_inside;
+} snat_interface_t;
+
+typedef struct {
+  /* User pool */
+  snat_user_t * users;
+
+  /* Session pool */
+  snat_session_t * sessions;
+
+  /* Pool of doubly-linked list elements */
+  dlist_elt_t * list_pool;
+} snat_main_per_thread_data_t;
+
+typedef struct {
+  /* Main lookup tables */
+  clib_bihash_8_8_t out2in;
+  clib_bihash_8_8_t in2out;
+
+  /* Find-a-user => src address lookup */
+  clib_bihash_8_8_t user_hash;
+
+  /* Non-translated packets worker lookup => src address + VRF */
+  clib_bihash_8_8_t worker_by_in;
+
+  /* Translated packets worker lookup => IP address + port number */
+  clib_bihash_8_8_t worker_by_out;
+
+  u32 num_workers;
+  u32 first_worker_index;
+  u32 next_worker;
+  u32 * workers;
+
+  /* Per thread data */
+  snat_main_per_thread_data_t * per_thread_data;
+
+  /* Find a static mapping by local */
+  clib_bihash_8_8_t static_mapping_by_local;
+
+  /* Find a static mapping by external */
+  clib_bihash_8_8_t static_mapping_by_external;
+
+  /* Static mapping pool */
+  snat_static_mapping_t * static_mappings;
+
+  /* Interface pool */
+  snat_interface_t * interfaces;
+
+  /* Vector of outside addresses */
+  snat_address_t * addresses;
+
+  /* Randomize port allocation order */
+  u32 random_seed;
+
+  /* Worker handoff index */
+  u32 fq_in2out_index;
+  u32 fq_out2in_index;
+
+  /* Config parameters */
+  u8 static_mapping_only;
+  u8 static_mapping_connection_tracking;
+  u32 translation_buckets;
+  u32 translation_memory_size;
+  u32 user_buckets;
+  u32 user_memory_size;
+  u32 max_translations_per_user;
+  u32 outside_vrf_id;
+  u32 outside_fib_index;
+  u32 inside_vrf_id;
+  u32 inside_fib_index;
+
+  /* API message ID base */
+  u16 msg_id_base;
+
+  /* convenience */
+  vlib_main_t * vlib_main;
+  vnet_main_t * vnet_main;
+  ip4_main_t * ip4_main;
+  ip_lookup_main_t * ip4_lookup_main;
+  ethernet_main_t * ethernet_main;  
+  api_main_t * api_main;
+} snat_main_t;
+
+extern snat_main_t snat_main;
+extern vlib_node_registration_t snat_in2out_node;
+extern vlib_node_registration_t snat_out2in_node;
+extern vlib_node_registration_t snat_in2out_fast_node;
+extern vlib_node_registration_t snat_out2in_fast_node;
+extern vlib_node_registration_t snat_in2out_worker_handoff_node;
+extern vlib_node_registration_t snat_out2in_worker_handoff_node;
+
+void snat_free_outside_address_and_port (snat_main_t * sm, 
+                                         snat_session_key_t * k, 
+                                         u32 address_index);
+
+int snat_alloc_outside_address_and_port (snat_main_t * sm, 
+                                         snat_session_key_t * k,
+                                         u32 * address_indexp);
+
+int snat_static_mapping_match (snat_main_t * sm,
+                               snat_session_key_t match,
+                               snat_session_key_t * mapping,
+                               u8 by_external);
+
+format_function_t format_snat_user;
+
+typedef struct {
+  u32 cached_sw_if_index;
+  u32 cached_ip4_address;
+} snat_runtime_t;
+
+/** \brief Check if SNAT session is created from static mapping.
+    @param s SNAT session
+    @return 1 if SNAT session is created from static mapping otherwise 0
+*/
+#define snat_is_session_static(s) s->flags & SNAT_SESSION_FLAG_STATIC_MAPPING
+
+/* 
+ * Why is this here? Because we don't need to touch this layer to
+ * simply reply to an icmp. We need to change id to a unique
+ * value to NAT an echo request/reply.
+ */
+   
+typedef struct {
+  u16 identifier;
+  u16 sequence;
+} icmp_echo_header_t;
+
+#endif /* __included_snat_h__ */
diff --git a/src/plugins/snat/snat_all_api_h.h b/src/plugins/snat/snat_all_api_h.h
new file mode 100644
index 00000000000..490177008e0
--- /dev/null
+++ b/src/plugins/snat/snat_all_api_h.h
@@ -0,0 +1,19 @@
+
+/*
+ * snat_all_api_h.h - skeleton vpp engine plug-in api #include file
+ *
+ * Copyright (c) <current-year> <your-organization>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/* Include the generated file, see BUILT_SOURCES in Makefile.am */
+#include <snat/snat.api.h>
diff --git a/src/plugins/snat/snat_msg_enum.h b/src/plugins/snat/snat_msg_enum.h
new file mode 100644
index 00000000000..2c76fd51158
--- /dev/null
+++ b/src/plugins/snat/snat_msg_enum.h
@@ -0,0 +1,31 @@
+
+/*
+ * snat_msg_enum.h - skeleton vpp engine plug-in message enumeration
+ *
+ * Copyright (c) <current-year> <your-organization>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef included_snat_msg_enum_h
+#define included_snat_msg_enum_h
+
+#include <vppinfra/byte_order.h>
+
+#define vl_msg_id(n,h) n,
+typedef enum {
+#include <snat/snat_all_api_h.h>
+    /* We'll want to know how many messages IDs we need... */
+    VL_MSG_FIRST_AVAILABLE,
+} vl_msg_id_t;
+#undef vl_msg_id
+
+#endif /* included_snat_msg_enum_h */
diff --git a/src/plugins/snat/snat_test.c b/src/plugins/snat/snat_test.c
new file mode 100644
index 00000000000..2a003ba60c6
--- /dev/null
+++ b/src/plugins/snat/snat_test.c
@@ -0,0 +1,602 @@
+
+/*
+ * snat.c - skeleton vpp-api-test plug-in 
+ *
+ * Copyright (c) <current-year> <your-organization>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <vat/vat.h>
+#include <vlibapi/api.h>
+#include <vlibmemory/api.h>
+#include <vlibsocket/api.h>
+#include <vppinfra/error.h>
+#include <vnet/ip/ip.h>
+
+uword unformat_sw_if_index (unformat_input_t * input, va_list * args);
+
+/* Declare message IDs */
+#include <snat/snat_msg_enum.h>
+
+/* define message structures */
+#define vl_typedefs
+#include <snat/snat_all_api_h.h> 
+#undef vl_typedefs
+
+/* declare message handlers for each api */
+
+#define vl_endianfun             /* define message structures */
+#include <snat/snat_all_api_h.h> 
+#undef vl_endianfun
+
+/* instantiate all the print functions we know about */
+#define vl_print(handle, ...)
+#define vl_printfun
+#include <snat/snat_all_api_h.h> 
+#undef vl_printfun
+
+/* Get the API version number. */
+#define vl_api_version(n,v) static u32 api_version=(v);
+#include <snat/snat_all_api_h.h>
+#undef vl_api_version
+
+typedef struct {
+    /* API message ID base */
+    u16 msg_id_base;
+    vat_main_t *vat_main;
+} snat_test_main_t;
+
+snat_test_main_t snat_test_main;
+
+#define foreach_standard_reply_retval_handler   \
+_(snat_add_address_range_reply)                 \
+_(snat_interface_add_del_feature_reply)         \
+_(snat_add_static_mapping_reply)                \
+_(snat_set_workers_reply)
+
+#define _(n)                                            \
+    static void vl_api_##n##_t_handler                  \
+    (vl_api_##n##_t * mp)                               \
+    {                                                   \
+        vat_main_t * vam = snat_test_main.vat_main;   \
+        i32 retval = ntohl(mp->retval);                 \
+        if (vam->async_mode) {                          \
+            vam->async_errors += (retval < 0);          \
+        } else {                                        \
+            vam->retval = retval;                       \
+            vam->result_ready = 1;                      \
+        }                                               \
+    }
+foreach_standard_reply_retval_handler;
+#undef _
+
+/* 
+ * Table of message reply handlers, must include boilerplate handlers
+ * we just generated
+ */
+#define foreach_vpe_api_reply_msg                               \
+_(SNAT_ADD_ADDRESS_RANGE_REPLY, snat_add_address_range_reply)   \
+_(SNAT_INTERFACE_ADD_DEL_FEATURE_REPLY,                         \
+  snat_interface_add_del_feature_reply)                         \
+_(SNAT_ADD_STATIC_MAPPING_REPLY, snat_add_static_mapping_reply) \
+_(SNAT_CONTROL_PING_REPLY, snat_control_ping_reply)             \
+_(SNAT_STATIC_MAPPING_DETAILS, snat_static_mapping_details)     \
+_(SNAT_SHOW_CONFIG_REPLY, snat_show_config_reply)               \
+_(SNAT_ADDRESS_DETAILS, snat_address_details)                   \
+_(SNAT_INTERFACE_DETAILS, snat_interface_details)               \
+_(SNAT_SET_WORKERS_REPLY, snat_set_workers_reply)               \
+_(SNAT_WORKER_DETAILS, snat_worker_details)
+
+/* M: construct, but don't yet send a message */
+#define M(T,t)                                                  \
+do {                                                            \
+    vam->result_ready = 0;                                      \
+    mp = vl_msg_api_alloc(sizeof(*mp));                         \
+    memset (mp, 0, sizeof (*mp));                               \
+    mp->_vl_msg_id = ntohs (VL_API_##T + sm->msg_id_base);      \
+    mp->client_index = vam->my_client_index;                    \
+} while(0);
+
+#define M2(T,t,n)                                               \
+do {                                                            \
+    vam->result_ready = 0;                                      \
+    mp = vl_msg_api_alloc(sizeof(*mp)+(n));                     \
+    memset (mp, 0, sizeof (*mp));                               \
+    mp->_vl_msg_id = ntohs (VL_API_##T + sm->msg_id_base);      \
+    mp->client_index = vam->my_client_index;                    \
+} while(0);
+
+/* S: send a message */
+#define S (vl_msg_api_send_shmem (vam->vl_input_queue, (u8 *)&mp))
+
+/* W: wait for results, with timeout */
+#define W                                       \
+do {                                            \
+    timeout = vat_time_now (vam) + 1.0;         \
+                                                \
+    while (vat_time_now (vam) < timeout) {      \
+        if (vam->result_ready == 1) {           \
+            return (vam->retval);               \
+        }                                       \
+    }                                           \
+    return -99;                                 \
+} while(0);
+
+static int api_snat_add_address_range (vat_main_t * vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  unformat_input_t * i = vam->input;
+  f64 timeout;
+  ip4_address_t start_addr, end_addr;
+  u32 start_host_order, end_host_order;
+  vl_api_snat_add_address_range_t * mp;
+  u8 is_add = 1;
+  int count;
+
+  while (unformat_check_input (i) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (i, "%U - %U",
+                    unformat_ip4_address, &start_addr,
+                    unformat_ip4_address, &end_addr))
+        ;
+      else if (unformat (i, "%U", unformat_ip4_address, &start_addr))
+        end_addr = start_addr;
+      else if (unformat (i, "del"))
+        is_add = 0;
+      else
+        {
+          clib_warning("unknown input '%U'", format_unformat_error, i);
+          return -99;
+        }
+    }
+
+  start_host_order = clib_host_to_net_u32 (start_addr.as_u32);
+  end_host_order = clib_host_to_net_u32 (end_addr.as_u32);
+  
+  if (end_host_order < start_host_order)
+    {
+      errmsg ("end address less than start address\n");
+      return -99;
+    }
+
+  count = (end_host_order - start_host_order) + 1;
+
+  if (count > 1024)
+    {
+    errmsg ("%U - %U, %d addresses...\n",
+           format_ip4_address, &start_addr,
+           format_ip4_address, &end_addr,
+           count);
+    }
+  
+  M(SNAT_ADD_ADDRESS_RANGE, snat_add_address_range);
+
+  memcpy (mp->first_ip_address, &start_addr, 4);
+  memcpy (mp->last_ip_address, &end_addr, 4);
+  mp->is_ip4 = 1;
+  mp->is_add = is_add;
+
+  S; W;
+
+  /* NOTREACHED */
+  return 0;
+}
+
+static int api_snat_interface_add_del_feature (vat_main_t * vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  unformat_input_t * i = vam->input;
+  f64 timeout;
+  vl_api_snat_interface_add_del_feature_t * mp;
+  u32 sw_if_index;
+  u8 sw_if_index_set = 0;
+  u8 is_inside = 1; 
+  u8 is_add = 1;
+
+  while (unformat_check_input (i) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (i, "%U", unformat_sw_if_index, vam, &sw_if_index))
+        sw_if_index_set = 1;
+      else if (unformat (i, "sw_if_index %d", &sw_if_index))
+        sw_if_index_set = 1;
+      else if (unformat (i, "out"))
+        is_inside = 0;
+      else if (unformat (i, "in"))
+        is_inside = 1;
+      else if (unformat (i, "del"))
+        is_add = 0;
+      else
+        {
+          clib_warning("unknown input '%U'", format_unformat_error, i);
+          return -99;
+        }
+    }
+
+  if (sw_if_index_set == 0)
+    {
+      errmsg ("interface / sw_if_index required\n");
+      return -99;
+    }
+
+  M(SNAT_INTERFACE_ADD_DEL_FEATURE, snat_interface_add_del_feature);
+  mp->sw_if_index = ntohl(sw_if_index);
+  mp->is_add = is_add;
+  mp->is_inside = is_inside;
+  
+  S; W;
+  /* NOTREACHED */
+  return 0;
+}
+
+static int api_snat_add_static_mapping(vat_main_t * vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  unformat_input_t * i = vam->input;
+  f64 timeout;
+  vl_api_snat_add_static_mapping_t * mp;
+  u8 addr_set_n = 0;
+  u8 is_add = 1;
+  u8 addr_only = 1;
+  ip4_address_t local_addr, external_addr;
+  u32 local_port = 0, external_port = 0, vrf_id = ~0;
+
+  while (unformat_check_input (i) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (i, "local_addr %U", unformat_ip4_address, &local_addr))
+        addr_set_n++;
+      else if (unformat (i, "external_addr %U", unformat_ip4_address,
+                         &external_addr))
+        addr_set_n++;
+      else if (unformat (i, "local_port %u", &local_port))
+        addr_only = 0;
+      else if (unformat (i, "external_port %u", &external_port))
+        addr_only = 0;
+      else if (unformat (i, "vrf %u", &vrf_id))
+        ;
+      else if (unformat (i, "del"))
+        is_add = 0;
+      else
+        {
+          clib_warning("unknown input '%U'", format_unformat_error, i);
+          return -99;
+        }
+    }
+
+  if (addr_set_n != 2)
+    {
+      errmsg ("local_addr and remote_addr required\n");
+      return -99;
+    }
+
+  M(SNAT_ADD_STATIC_MAPPING, snat_add_static_mapping);
+  mp->is_add = is_add;
+  mp->is_ip4 = 1;
+  mp->addr_only = addr_only;
+  mp->local_port = ntohs ((u16) local_port);
+  mp->external_port = ntohs ((u16) external_port);
+  mp->vrf_id = ntohl (vrf_id);
+  memcpy (mp->local_ip_address, &local_addr, 4);
+  memcpy (mp->external_ip_address, &external_addr, 4);
+
+  S; W;
+  /* NOTREACHED */
+  return 0;
+}
+
+static void vl_api_snat_control_ping_reply_t_handler
+  (vl_api_snat_control_ping_reply_t * mp)
+{
+  vat_main_t *vam = &vat_main;
+  i32 retval = ntohl (mp->retval);
+  if (vam->async_mode)
+    {
+      vam->async_errors += (retval < 0);
+    }
+  else
+    {
+      vam->retval = retval;
+      vam->result_ready = 1;
+    }
+}
+
+static void vl_api_snat_static_mapping_details_t_handler
+  (vl_api_snat_static_mapping_details_t *mp)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  vat_main_t *vam = sm->vat_main;
+
+  if (mp->addr_only)
+      fformat (vam->ofp, "%15U%6s%15U%6s%11d\n",
+               format_ip4_address, &mp->local_ip_address, "",
+               format_ip4_address, &mp->external_ip_address, "",
+               ntohl (mp->vrf_id));
+  else
+      fformat (vam->ofp, "%15U%6d%15U%6d%11d\n",
+               format_ip4_address, &mp->local_ip_address,
+               ntohs (mp->local_port),
+               format_ip4_address, &mp->external_ip_address,
+               ntohs (mp->external_port),
+               ntohl (mp->vrf_id));
+
+}
+
+static int api_snat_static_mapping_dump(vat_main_t * vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  f64 timeout;
+  vl_api_snat_static_mapping_dump_t * mp;
+
+  if (vam->json_output)
+    {
+      clib_warning ("JSON output not supported for snat_static_mapping_dump");
+      return -99;
+    }
+
+  fformat (vam->ofp, "%21s%21s\n", "local", "external");
+  fformat (vam->ofp, "%15s%6s%15s%6s%11s\n", "address", "port", "address",
+           "port", "vrf");
+
+  M(SNAT_STATIC_MAPPING_DUMP, snat_static_mapping_dump);
+  S;
+  /* Use a control ping for synchronization */
+  {
+    vl_api_snat_control_ping_t *mp;
+    M (SNAT_CONTROL_PING, snat_control_ping);
+    S;
+  }
+  W;
+  /* NOTREACHED */
+  return 0;
+}
+
+static void vl_api_snat_show_config_reply_t_handler
+  (vl_api_snat_show_config_reply_t *mp)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  vat_main_t *vam = sm->vat_main;
+  i32 retval = ntohl (mp->retval);
+
+  if (retval >= 0)
+    {
+      fformat (vam->ofp, "translation hash buckets %d\n",
+               ntohl (mp->translation_buckets));
+      fformat (vam->ofp, "translation hash memory %d\n",
+               ntohl (mp->translation_memory_size));
+      fformat (vam->ofp, "user hash buckets %d\n", ntohl (mp->user_buckets));
+      fformat (vam->ofp, "user hash memory %d\n", ntohl (mp->user_memory_size));
+      fformat (vam->ofp, "max translations per user %d\n",
+               ntohl (mp->max_translations_per_user));
+      fformat (vam->ofp, "outside VRF id %d\n", ntohl (mp->outside_vrf_id));
+      fformat (vam->ofp, "inside VRF id %d\n", ntohl (mp->inside_vrf_id));
+      if (mp->static_mapping_only)
+        {
+          fformat (vam->ofp, "static mapping only");
+          if (mp->static_mapping_connection_tracking)
+            fformat (vam->ofp, " connection tracking");
+          fformat (vam->ofp, "\n");
+        }
+    }
+  vam->retval = retval;
+  vam->result_ready = 1;
+}
+
+static int api_snat_show_config(vat_main_t * vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  f64 timeout;
+  vl_api_snat_show_config_t * mp;
+
+  if (vam->json_output)
+    {
+      clib_warning ("JSON output not supported for snat_show_config");
+      return -99;
+    }
+
+  M(SNAT_SHOW_CONFIG, snat_show_config);
+  S; W;
+  /* NOTREACHED */
+  return 0;
+}
+
+static void vl_api_snat_address_details_t_handler
+  (vl_api_snat_address_details_t *mp)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  vat_main_t *vam = sm->vat_main;
+
+  fformat (vam->ofp, "%U\n", format_ip4_address, &mp->ip_address);
+}
+
+static int api_snat_address_dump(vat_main_t * vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  f64 timeout;
+  vl_api_snat_address_dump_t * mp;
+
+  if (vam->json_output)
+    {
+      clib_warning ("JSON output not supported for snat_address_dump");
+      return -99;
+    }
+
+  M(SNAT_ADDRESS_DUMP, snat_address_dump);
+  S;
+  /* Use a control ping for synchronization */
+  {
+    vl_api_snat_control_ping_t *mp;
+    M (SNAT_CONTROL_PING, snat_control_ping);
+    S;
+  }
+  W;
+  /* NOTREACHED */
+  return 0;
+}
+
+static void vl_api_snat_interface_details_t_handler
+  (vl_api_snat_interface_details_t *mp)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  vat_main_t *vam = sm->vat_main;
+
+  fformat (vam->ofp, "sw_if_index %d %s\n", ntohl (mp->sw_if_index),
+           mp->is_inside ? "in" : "out");
+}
+
+static int api_snat_interface_dump(vat_main_t * vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  f64 timeout;
+  vl_api_snat_interface_dump_t * mp;
+
+  if (vam->json_output)
+    {
+      clib_warning ("JSON output not supported for snat_address_dump");
+      return -99;
+    }
+
+  M(SNAT_INTERFACE_DUMP, snat_interface_dump);
+  S;
+  /* Use a control ping for synchronization */
+  {
+    vl_api_snat_control_ping_t *mp;
+    M (SNAT_CONTROL_PING, snat_control_ping);
+    S;
+  }
+  W;
+  /* NOTREACHED */
+  return 0;
+}
+
+static int api_snat_set_workers (vat_main_t * vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  unformat_input_t * i = vam->input;
+  f64 timeout;
+  vl_api_snat_set_workers_t * mp;
+  uword *bitmap;
+
+  while (unformat_check_input (i) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (i, "%U", unformat_bitmap_list, &bitmap))
+        ;
+      else
+        {
+          clib_warning("unknown input '%U'", format_unformat_error, i);
+          return -99;
+        }
+    }
+
+  M(SNAT_SET_WORKERS, snat_set_workers);
+  mp->worker_mask = clib_host_to_net_u64 (bitmap[0]);
+
+  S; W;
+
+  /* NOTREACHED */
+  return 0;
+}
+
+static void vl_api_snat_worker_details_t_handler
+  (vl_api_snat_worker_details_t *mp)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  vat_main_t *vam = sm->vat_main;
+
+  fformat (vam->ofp, "worker_index %d (%s at lcore %u)\n",
+           ntohl (mp->worker_index), mp->name, ntohl (mp->lcore_id));
+}
+
+static int api_snat_worker_dump(vat_main_t * vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  f64 timeout;
+  vl_api_snat_worker_dump_t * mp;
+
+  if (vam->json_output)
+    {
+      clib_warning ("JSON output not supported for snat_address_dump");
+      return -99;
+    }
+
+  M(SNAT_WORKER_DUMP, snat_worker_dump);
+  S;
+  /* Use a control ping for synchronization */
+  {
+    vl_api_snat_control_ping_t *mp;
+    M (SNAT_CONTROL_PING, snat_control_ping);
+    S;
+  }
+  W;
+  /* NOTREACHED */
+  return 0;
+}
+
+/* 
+ * List of messages that the api test plugin sends,
+ * and that the data plane plugin processes
+ */
+#define foreach_vpe_api_msg                                      \
+_(snat_add_address_range, "<start-addr> [- <end-addr] [del]")    \
+_(snat_interface_add_del_feature,                                \
+  "<intfc> | sw_if_index <id> [in] [out] [del]")                 \
+_(snat_add_static_mapping, "local_addr <ip> external_addr <ip> " \
+  "[local_port <n>] [external_port <n>] [vrf <table-id>] [del]") \
+_(snat_set_workers, "<wokrers_bitmap>")                          \
+_(snat_static_mapping_dump, "")                                  \
+_(snat_show_config, "")                                          \
+_(snat_address_dump, "")                                         \
+_(snat_interface_dump, "")                                       \
+_(snat_worker_dump, "")
+
+void vat_api_hookup (vat_main_t *vam)
+{
+  snat_test_main_t * sm __attribute__((unused)) = &snat_test_main;
+  /* Hook up handlers for replies from the data plane plug-in */
+#define _(N,n)                                                  \
+  vl_msg_api_set_handlers((VL_API_##N + sm->msg_id_base),       \
+                          #n,                                   \
+                          vl_api_##n##_t_handler,               \
+                          vl_noop_handler,                      \
+                          vl_api_##n##_t_endian,                \
+                          vl_api_##n##_t_print,                 \
+                          sizeof(vl_api_##n##_t), 1); 
+  foreach_vpe_api_reply_msg;
+#undef _
+
+  /* API messages we can send */
+#define _(n,h) hash_set_mem (vam->function_by_name, #n, api_##n);
+  foreach_vpe_api_msg;
+#undef _    
+    
+  /* Help strings */
+#define _(n,h) hash_set_mem (vam->help_by_name, #n, h);
+  foreach_vpe_api_msg;
+#undef _
+}
+
+clib_error_t * vat_plugin_register (vat_main_t *vam)
+{
+  snat_test_main_t * sm = &snat_test_main;
+  u8 * name;
+
+  sm->vat_main = vam;
+
+  /* Ask the vpp engine for the first assigned message-id */
+  name = format (0, "snat_%08x%c", api_version, 0);
+  sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
+
+  if (sm->msg_id_base != (u16) ~0)
+    vat_api_hookup (vam);
+  
+  vec_free(name);
+  
+  return 0;
+}