BFD: SHA1 authentication

Add authentication support to BFD feature. Out of three existing
authentication types, implement SHA1 (sole RFC requirement). Simple
password is insecure and MD5 is discouraged by the RFC, so ignore
those.
Add/change APIs to allow configuring BFD authentication keys
and their usage with BFD sessions.

Change-Id: Ifb0fb5b19c2e72196d84c1cde919bd4c074ea415
Signed-off-by: Klement Sekera <ksekera@cisco.com>

1 files changed, 696 insertions, 37 deletions

diff --git a/test/test_bfd.py b/test/test_bfd.py
index d047b5a3b99..5f8614777ca 100644
--- a/test/test_bfd.py
+++ b/test/test_bfd.py
@@ -1,6 +1,8 @@
 #!/usr/bin/env python
 
 import unittest
+import hashlib
+import binascii
 import time
 from random import randint
 from bfd import *
@@ -10,6 +12,22 @@ from util import ppp
 us_in_sec = 1000000
 
 
+class AuthKeyFactory(object):
+    """Factory class for creating auth keys with unique conf key ID"""
+
+    def __init__(self):
+        self._conf_key_ids = {}
+
+    def create_random_key(self, test, auth_type=BFDAuthType.keyed_sha1):
+        conf_key_id = randint(0, 0xFFFFFFFF)
+        while conf_key_id in self._conf_key_ids:
+            conf_key_id = randint(0, 0xFFFFFFFF)
+        self._conf_key_ids[conf_key_id] = 1
+        key = str(bytearray([randint(0, 255) for j in range(randint(1, 20))]))
+        return VppBFDAuthKey(test=test, auth_type=auth_type,
+                             conf_key_id=conf_key_id, key=key)
+
+
 class BFDAPITestCase(VppTestCase):
     """Bidirectional Forwarding Detection (BFD) - API"""
 
@@ -21,19 +39,23 @@ class BFDAPITestCase(VppTestCase):
             cls.create_pg_interfaces(range(2))
             for i in cls.pg_interfaces:
                 i.config_ip4()
+                i.config_ip6()
                 i.resolve_arp()
 
         except Exception:
             super(BFDAPITestCase, cls).tearDownClass()
             raise
 
+    def setUp(self):
+        super(BFDAPITestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+
     def test_add_bfd(self):
         """ create a BFD session """
         session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
         session.add_vpp_config()
         self.logger.debug("Session state is %s" % str(session.state))
         session.remove_vpp_config()
-        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
         session.add_vpp_config()
         self.logger.debug("Session state is %s" % str(session.state))
         session.remove_vpp_config()
@@ -48,25 +70,155 @@ class BFDAPITestCase(VppTestCase):
 
         session.remove_vpp_config()
 
-    def test_add_two(self):
-        """ create two BFD sessions """
-        session1 = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
-        session1.add_vpp_config()
-        session2 = VppBFDUDPSession(self, self.pg1, self.pg1.remote_ip4)
-        session2.add_vpp_config()
-        self.assertNotEqual(session1.bs_index, session2.bs_index,
-                            "Different BFD sessions share bs_index (%s)" %
-                            session1.bs_index)
+    def test_add_bfd6(self):
+        """ create IPv6 BFD session """
+        session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6)
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s" % str(session.state))
+        session.remove_vpp_config()
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s" % str(session.state))
+        session.remove_vpp_config()
+
+    def test_add_sha1_keys(self):
+        """ add SHA1 keys """
+        key_count = 10
+        keys = [self.factory.create_random_key(
+            self) for i in range(0, key_count)]
+        for key in keys:
+            self.assertFalse(key.query_vpp_config())
+        for key in keys:
+            key.add_vpp_config()
+        for key in keys:
+            self.assertTrue(key.query_vpp_config())
+        # remove randomly
+        indexes = range(key_count)
+        random.shuffle(indexes)
+        removed = []
+        for i in indexes:
+            key = keys[i]
+            key.remove_vpp_config()
+            removed.append(i)
+            for j in range(key_count):
+                key = keys[j]
+                if j in removed:
+                    self.assertFalse(key.query_vpp_config())
+                else:
+                    self.assertTrue(key.query_vpp_config())
+        # should be removed now
+        for key in keys:
+            self.assertFalse(key.query_vpp_config())
+        # add back and remove again
+        for key in keys:
+            key.add_vpp_config()
+        for key in keys:
+            self.assertTrue(key.query_vpp_config())
+        for key in keys:
+            key.remove_vpp_config()
+        for key in keys:
+            self.assertFalse(key.query_vpp_config())
+
+    def test_add_bfd_sha1(self):
+        """ create a BFD session (SHA1) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                                   sha1_key=key)
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s" % str(session.state))
+        session.remove_vpp_config()
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s" % str(session.state))
+        session.remove_vpp_config()
+
+    def test_double_add_sha1(self):
+        """ create the same BFD session twice (negative case) (SHA1) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                                   sha1_key=key)
+        session.add_vpp_config()
+        with self.assertRaises(Exception):
+            session.add_vpp_config()
+
+    def test_add_authenticated_with_nonexistent_key(self):
+        """ create BFD session using non-existent SHA1 (negative case) """
+        session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4,
+            sha1_key=self.factory.create_random_key(self))
+        with self.assertRaises(Exception):
+            session.add_vpp_config()
+
+    def test_shared_sha1_key(self):
+        """ share single SHA1 key between multiple BFD sessions """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        sessions = [
+            VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                             sha1_key=key),
+            VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip6,
+                             sha1_key=key, af=AF_INET6),
+            VppBFDUDPSession(self, self.pg1, self.pg1.remote_ip4,
+                             sha1_key=key),
+            VppBFDUDPSession(self, self.pg1, self.pg1.remote_ip6,
+                             sha1_key=key, af=AF_INET6)]
+        for s in sessions:
+            s.add_vpp_config()
+        removed = 0
+        for s in sessions:
+            e = key.get_bfd_auth_keys_dump_entry()
+            self.assert_equal(e.use_count, len(sessions) - removed,
+                              "Use count for shared key")
+            s.remove_vpp_config()
+            removed += 1
+        e = key.get_bfd_auth_keys_dump_entry()
+        self.assert_equal(e.use_count, len(sessions) - removed,
+                          "Use count for shared key")
+
+    def test_activate_auth(self):
+        """ activate SHA1 authentication """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        session.add_vpp_config()
+        session.activate_auth(key)
+
+    def test_deactivate_auth(self):
+        """ deactivate SHA1 authentication """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        session.add_vpp_config()
+        session.activate_auth(key)
+        session.deactivate_auth()
+
+    def test_change_key(self):
+        key1 = self.factory.create_random_key(self)
+        key2 = self.factory.create_random_key(self)
+        while key2.conf_key_id == key1.conf_key_id:
+            key2 = self.factory.create_random_key(self)
+        key1.add_vpp_config()
+        key2.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                                   sha1_key=key1)
+        session.add_vpp_config()
+        session.activate_auth(key2)
 
 
 class BFDTestSession(object):
     """ BFD session as seen from test framework side """
 
-    def __init__(self, test, interface, af, detect_mult=3):
+    def __init__(self, test, interface, af, detect_mult=3, sha1_key=None,
+                 bfd_key_id=None, our_seq_number=0xFFFFFFFF - 4):
         self.test = test
         self.af = af
+        self.sha1_key = sha1_key
+        self.bfd_key_id = bfd_key_id
         self.interface = interface
         self.udp_sport = 50000
+        self.our_seq_number = our_seq_number
+        self.vpp_seq_number = None
         self.bfd_values = {
             'my_discriminator': 0,
             'desired_min_tx_interval': 100000,
@@ -74,10 +226,25 @@ class BFDTestSession(object):
             'diag': BFDDiagCode.no_diagnostic,
         }
 
+    def inc_seq_num(self):
+        if self.our_seq_number == 0xFFFFFFFF:
+            self.our_seq_number = 0
+        else:
+            self.our_seq_number += 1
+
     def update(self, **kwargs):
         self.bfd_values.update(kwargs)
 
     def create_packet(self):
+        if self.sha1_key:
+            bfd = BFD(flags="A")
+            bfd.auth_type = self.sha1_key.auth_type
+            bfd.auth_len = BFD.sha1_auth_len
+            bfd.auth_key_id = self.bfd_key_id
+            bfd.auth_seq_num = self.our_seq_number
+            bfd.length = BFD.sha1_auth_len + BFD.bfd_pkt_len
+        else:
+            bfd = BFD()
         if self.af == AF_INET6:
             packet = (Ether(src=self.interface.remote_mac,
                             dst=self.interface.local_mac) /
@@ -85,7 +252,7 @@ class BFDTestSession(object):
                            dst=self.interface.local_ip6,
                            hlim=255) /
                       UDP(sport=self.udp_sport, dport=BFD.udp_dport) /
-                      BFD())
+                      bfd)
         else:
             packet = (Ether(src=self.interface.remote_mac,
                             dst=self.interface.local_mac) /
@@ -93,11 +260,17 @@ class BFDTestSession(object):
                          dst=self.interface.local_ip4,
                          ttl=255) /
                       UDP(sport=self.udp_sport, dport=BFD.udp_dport) /
-                      BFD())
+                      bfd)
         self.test.logger.debug("BFD: Creating packet")
         for name, value in self.bfd_values.iteritems():
             self.test.logger.debug("BFD: setting packet.%s=%s", name, value)
             packet[BFD].setfieldval(name, value)
+        if self.sha1_key:
+            hash_material = str(packet[BFD])[:32] + self.sha1_key.key + \
+                "\0" * (20 - len(self.sha1_key.key))
+            self.test.logger.debug("BFD: Calculated SHA1 hash: %s" %
+                                   hashlib.sha1(hash_material).hexdigest())
+            packet[BFD].auth_key_hash = hashlib.sha1(hash_material).digest()
         return packet
 
     def send_packet(self):
@@ -106,13 +279,60 @@ class BFDTestSession(object):
         self.test.pg0.add_stream([p])
         self.test.pg_start()
 
-    def verify_packet(self, packet):
+    def verify_sha1_auth(self, packet):
+        """ Verify correctness of authentication in BFD layer. """
+        bfd = packet[BFD]
+        self.test.assert_equal(bfd.auth_len, 28, "Auth section length")
+        self.test.assert_equal(bfd.auth_type, self.sha1_key.auth_type,
+                               BFDAuthType)
+        self.test.assert_equal(bfd.auth_key_id, self.bfd_key_id, "Key ID")
+        self.test.assert_equal(bfd.auth_reserved, 0, "Reserved")
+        if self.vpp_seq_number is None:
+            self.vpp_seq_number = bfd.auth_seq_num
+            self.test.logger.debug("Received initial sequence number: %s" %
+                                   self.vpp_seq_number)
+        else:
+            recvd_seq_num = bfd.auth_seq_num
+            self.test.logger.debug("Received followup sequence number: %s" %
+                                   recvd_seq_num)
+            if self.vpp_seq_number < 0xffffffff:
+                if self.sha1_key.auth_type == \
+                        BFDAuthType.meticulous_keyed_sha1:
+                    self.test.assert_equal(recvd_seq_num,
+                                           self.vpp_seq_number + 1,
+                                           "BFD sequence number")
+                else:
+                    self.test.assert_in_range(recvd_seq_num,
+                                              self.vpp_seq_number,
+                                              self.vpp_seq_number + 1,
+                                              "BFD sequence number")
+            else:
+                if self.sha1_key.auth_type == \
+                        BFDAuthType.meticulous_keyed_sha1:
+                    self.test.assert_equal(recvd_seq_num, 0,
+                                           "BFD sequence number")
+                else:
+                    self.test.assertIn(recvd_seq_num, (self.vpp_seq_number, 0),
+                                       "BFD sequence number not one of "
+                                       "(%s, 0)" % self.vpp_seq_number)
+            self.vpp_seq_number = recvd_seq_num
+        # last 20 bytes represent the hash - so replace them with the key,
+        # pad the result with zeros and hash the result
+        hash_material = bfd.original[:-20] + self.sha1_key.key + \
+            "\0" * (20 - len(self.sha1_key.key))
+        expected_hash = hashlib.sha1(hash_material).hexdigest()
+        self.test.assert_equal(binascii.hexlify(bfd.auth_key_hash),
+                               expected_hash, "Auth key hash")
+
+    def verify_bfd(self, packet):
         """ Verify correctness of BFD layer. """
         bfd = packet[BFD]
         self.test.assert_equal(bfd.version, 1, "BFD version")
         self.test.assert_equal(bfd.your_discriminator,
                                self.bfd_values['my_discriminator'],
                                "BFD - your discriminator")
+        if self.sha1_key:
+            self.verify_sha1_auth(packet)
 
 
 class BFDCommonCode:
@@ -122,9 +342,9 @@ class BFDCommonCode:
         self.vapi.collect_events()  # clear the event queue
         if not self.vpp_dead:
             self.vapi.want_bfd_events(enable_disable=0)
-            self.vpp_session.remove_vpp_config()
 
     def bfd_session_up(self):
+        """ Bring BFD session up """
         self.pg_enable_capture([self.pg0])
         self.logger.info("BFD: Waiting for slow hello")
         p, timeout = self.wait_for_bfd_packet(2)
@@ -139,6 +359,18 @@ class BFDCommonCode:
         self.verify_event(e, expected_state=BFDState.up)
         self.logger.info("BFD: Session is Up")
         self.test_session.update(state=BFDState.up)
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def bfd_session_down(self):
+        """ Bring BFD session down """
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.test_session.update(state=BFDState.down)
+        self.test_session.send_packet()
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        self.verify_event(e, expected_state=BFDState.down)
+        self.logger.info("BFD: Session is Down")
+        self.assert_equal(self.vpp_session.state, BFDState.down, BFDState)
 
     def verify_ip(self, packet):
         """ Verify correctness of IP layer. """
@@ -166,12 +398,9 @@ class BFDCommonCode:
         """ Verify correctness of event values. """
         e = event
         self.logger.debug("BFD: Event: %s" % repr(e))
-        self.assert_equal(e.bs_index, self.vpp_session.bs_index,
-                          "BFD session index")
-        self.assert_equal(
-            e.sw_if_index,
-            self.vpp_session.interface.sw_if_index,
-            "BFD interface index")
+        self.assert_equal(e.sw_if_index,
+                          self.vpp_session.interface.sw_if_index,
+                          "BFD interface index")
         is_ipv6 = 0
         if self.vpp_session.af == AF_INET6:
             is_ipv6 = 1
@@ -199,7 +428,7 @@ class BFDCommonCode:
         before = time.time()
         p = self.pg0.wait_for_packet(timeout=timeout)
         after = time.time()
-        self.logger.debug(ppp("Got packet:", p))
+        self.logger.debug(ppp("BFD: Got packet:", p))
         bfd = p[BFD]
         if bfd is None:
             raise Exception(ppp("Unexpected or invalid BFD packet:", p))
@@ -207,20 +436,9 @@ class BFDCommonCode:
             raise Exception(ppp("Unexpected payload in BFD packet:", bfd))
         self.verify_ip(p)
         self.verify_udp(p)
-        self.test_session.verify_packet(p)
+        self.test_session.verify_bfd(p)
         return p, after - before
 
-    def test_session_up(self):
-        """ bring BFD session up """
-        self.bfd_session_up()
-
-    def test_hold_up(self):
-        """ hold BFD session up """
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
-            self.test_session.send_packet()
-
 
 class BFD4TestCase(VppTestCase, BFDCommonCode):
     """Bidirectional Forwarding Detection (BFD)"""
@@ -231,7 +449,6 @@ class BFD4TestCase(VppTestCase, BFDCommonCode):
         try:
             cls.create_pg_interfaces([0])
             cls.pg0.config_ip4()
-            cls.pg0.generate_remote_hosts()
             cls.pg0.configure_ipv4_neighbors()
             cls.pg0.admin_up()
             cls.pg0.resolve_arp()
@@ -242,6 +459,7 @@ class BFD4TestCase(VppTestCase, BFDCommonCode):
 
     def setUp(self):
         super(BFD4TestCase, self).setUp()
+        self.factory = AuthKeyFactory()
         self.vapi.want_bfd_events()
         try:
             self.vpp_session = VppBFDUDPSession(self, self.pg0,
@@ -255,7 +473,25 @@ class BFD4TestCase(VppTestCase, BFDCommonCode):
 
     def tearDown(self):
         BFDCommonCode.tearDown(self)
-        super(BFD4TestCase, self).tearDown()
+        VppTestCase.tearDown(self)
+
+    def test_session_up(self):
+        """ bring BFD session up """
+        self.bfd_session_up()
+
+    def test_session_down(self):
+        """ bring BFD session down """
+        self.bfd_session_up()
+        self.bfd_session_down()
+
+    def test_hold_up(self):
+        """ hold BFD session up """
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
 
     def test_slow_timer(self):
         """ verify slow periodic control frames while session down """
@@ -367,6 +603,7 @@ class BFD6TestCase(VppTestCase, BFDCommonCode):
 
     def setUp(self):
         super(BFD6TestCase, self).setUp()
+        self.factory = AuthKeyFactory()
         self.vapi.want_bfd_events()
         try:
             self.vpp_session = VppBFDUDPSession(self, self.pg0,
@@ -382,7 +619,429 @@ class BFD6TestCase(VppTestCase, BFDCommonCode):
 
     def tearDown(self):
         BFDCommonCode.tearDown(self)
-        super(BFD6TestCase, self).tearDown()
+        VppTestCase.tearDown(self)
+
+    def test_session_up(self):
+        """ bring BFD session up """
+        self.bfd_session_up()
+
+    def test_hold_up(self):
+        """ hold BFD session up """
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+
+class BFDSHA1TestCase(VppTestCase, BFDCommonCode):
+    """Bidirectional Forwarding Detection (BFD) (SHA1 auth) """
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDSHA1TestCase, cls).setUpClass()
+        try:
+            cls.create_pg_interfaces([0])
+            cls.pg0.config_ip4()
+            cls.pg0.admin_up()
+            cls.pg0.resolve_arp()
+
+        except Exception:
+            super(BFDSHA1TestCase, cls).tearDownClass()
+            raise
+
+    def setUp(self):
+        super(BFDSHA1TestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+        self.vapi.want_bfd_events()
+
+    def tearDown(self):
+        BFDCommonCode.tearDown(self)
+        VppTestCase.tearDown(self)
+
+    def test_session_up(self):
+        """ bring BFD session up """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4,
+                                            sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        self.bfd_session_up()
+
+    def test_hold_up(self):
+        """ hold BFD session up """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4,
+                                            sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def test_hold_up_meticulous(self):
+        """ hold BFD session up - meticulous auth """
+        key = self.factory.create_random_key(
+            self, BFDAuthType.meticulous_keyed_sha1)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.inc_seq_num()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def test_send_bad_seq_number(self):
+        """ session is not kept alive by msgs with bad seq numbers"""
+        key = self.factory.create_random_key(
+            self, BFDAuthType.meticulous_keyed_sha1)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        self.bfd_session_up()
+        self.wait_for_bfd_packet()
+        self.test_session.send_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+        self.wait_for_bfd_packet()
+        self.test_session.send_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+        self.wait_for_bfd_packet()
+        self.test_session.send_packet()
+        self.wait_for_bfd_packet()
+        self.test_session.send_packet()
+        e = self.vapi.collect_events()
+        # session should be down now, because the sequence numbers weren't
+        # updated
+        self.assert_equal(len(e), 1, "number of bfd events")
+        self.verify_event(e[0], expected_state=BFDState.down)
+
+    def execute_rogue_session_scenario(self, vpp_bfd_udp_session,
+                                       legitimate_test_session,
+                                       rogue_test_session,
+                                       rogue_bfd_values=None):
+        """ execute a rogue session interaction scenario
+
+        1. create vpp session, add config
+        2. bring the legitimate session up
+        3. copy the bfd values from legitimate session to rogue session
+        4. apply rogue_bfd_values to rogue session
+        5. set rogue session state to down
+        6. send message to take the session down from the rogue session
+        7. assert that the legitimate session is unaffected
+        """
+
+        self.vpp_session = vpp_bfd_udp_session
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = legitimate_test_session
+        # bring vpp session up
+        self.bfd_session_up()
+        # send packet from rogue session
+        rogue_test_session.bfd_values = self.test_session.bfd_values.copy()
+        if rogue_bfd_values:
+            rogue_test_session.update(**rogue_bfd_values)
+        rogue_test_session.update(state=BFDState.down)
+        rogue_test_session.send_packet()
+        self.wait_for_bfd_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def test_mismatch_auth(self):
+        """ session is not brought down by unauthenticated msg """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+        legitimate_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id)
+        rogue_test_session = BFDTestSession(self, self.pg0, AF_INET)
+        self.execute_rogue_session_scenario(vpp_session,
+                                            legitimate_test_session,
+                                            rogue_test_session)
+
+    def test_mismatch_bfd_key_id(self):
+        """ session is not brought down by msg with non-existent key-id """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+        # pick a different random bfd key id
+        x = randint(0, 255)
+        while x == vpp_session.bfd_key_id:
+            x = randint(0, 255)
+        legitimate_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id)
+        rogue_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key, bfd_key_id=x)
+        self.execute_rogue_session_scenario(vpp_session,
+                                            legitimate_test_session,
+                                            rogue_test_session)
+
+    def test_mismatched_auth_type(self):
+        """ session is not brought down by msg with wrong auth type """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+        legitimate_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id)
+        rogue_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id)
+        self.execute_rogue_session_scenario(
+            vpp_session, legitimate_test_session, rogue_test_session,
+            {'auth_type': BFDAuthType.keyed_md5})
+
+    def test_restart(self):
+        """ simulate remote peer restart and resynchronization """
+        key = self.factory.create_random_key(
+            self, BFDAuthType.meticulous_keyed_sha1)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id, our_seq_number=0)
+        self.bfd_session_up()
+        # now we need to not respond for 2*detection_time (4 packets)
+        self.wait_for_bfd_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+        self.wait_for_bfd_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        self.verify_event(e, expected_state=BFDState.down)
+        self.test_session.update(state=BFDState.down)
+        self.wait_for_bfd_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+        self.wait_for_bfd_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+        # reset sequence number
+        self.test_session.our_seq_number = 0
+        self.bfd_session_up()
+
+
+class BFDAuthOnOffTestCase(VppTestCase, BFDCommonCode):
+    """Bidirectional Forwarding Detection (BFD) (changing auth) """
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDAuthOnOffTestCase, cls).setUpClass()
+        try:
+            cls.create_pg_interfaces([0])
+            cls.pg0.config_ip4()
+            cls.pg0.admin_up()
+            cls.pg0.resolve_arp()
+
+        except Exception:
+            super(BFDAuthOnOffTestCase, cls).tearDownClass()
+            raise
+
+    def setUp(self):
+        super(BFDAuthOnOffTestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+        self.vapi.want_bfd_events()
+
+    def tearDown(self):
+        BFDCommonCode.tearDown(self)
+        VppTestCase.tearDown(self)
+
+    def test_auth_on_immediate(self):
+        """ turn auth on without disturbing session state (immediate) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(self, self.pg0, AF_INET)
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.vpp_session.activate_auth(key)
+        self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
+        self.test_session.sha1_key = key
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_off_immediate(self):
+        """ turn auth off without disturbing session state (immediate) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.vpp_session.deactivate_auth()
+        self.test_session.bfd_key_id = None
+        self.test_session.sha1_key = None
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_change_key_immediate(self):
+        """ change auth key without disturbing session state (immediate) """
+        key1 = self.factory.create_random_key(self)
+        key1.add_vpp_config()
+        key2 = self.factory.create_random_key(self)
+        key2.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key1)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key1,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.vpp_session.activate_auth(key2)
+        self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
+        self.test_session.sha1_key = key2
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_on_delayed(self):
+        """ turn auth on without disturbing session state (delayed) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(self, self.pg0, AF_INET)
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.vpp_session.activate_auth(key, delayed=True)
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
+        self.test_session.sha1_key = key
+        self.test_session.send_packet()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_off_delayed(self):
+        """ turn auth off without disturbing session state (delayed) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.vpp_session.deactivate_auth(delayed=True)
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.test_session.bfd_key_id = None
+        self.test_session.sha1_key = None
+        self.test_session.send_packet()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_change_key_delayed(self):
+        """ change auth key without disturbing session state (delayed) """
+        key1 = self.factory.create_random_key(self)
+        key1.add_vpp_config()
+        key2 = self.factory.create_random_key(self)
+        key2.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key1)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key1,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.vpp_session.activate_auth(key2, delayed=True)
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
+        self.test_session.sha1_key = key2
+        self.test_session.send_packet()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
 
 if __name__ == '__main__':
     unittest.main(testRunner=VppTestRunner)