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// Test set keepalive after accept
// Establish a connection.
0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+0 bind(3, ..., ...) = 0
+0 listen(3, 1) = 0
+0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>
+0 > S. 0:0(0) ack 1 <...>
+.1 < . 1:1(0) ack 1 win 32792
+0 accept(3, ..., ...) = 4
// enable keepalive and set args
+0 setsockopt(4, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
// extra ack, it's not needed, fix it later
+0 ~ +100 > . 1:1(0) ack 1
+0 setsockopt(4, IPPROTO_TCP, TCP_KEEPIDLE, [5], 4) = 0
// extra ack, it's not needed, fix it later
+0 ~ +100 > . 1:1(0) ack 1
+0 setsockopt(4, IPPROTO_TCP, TCP_KEEPINTVL, [2], 4) = 0
// extra ack, it's not needed, fix it later
+0 ~ +100 > . 1:1(0) ack 1
+0 setsockopt(4, IPPROTO_TCP, TCP_KEEPCNT, [2], 4) = 0
// first keep-alive pkt, idle = 5
+4 ~ +6 > . 0:0(0) ack 1
// second keep-alive pkt, interval = 2
+1 ~ +3 > . 0:0(0) ack 1
// get response, idle = 5
+0 < . 1:1(0) ack 1 win 32792
// first keep-alive pkt again, idle = 5
+4 ~ +6 > . 0:0(0) ack 1
// second keep-alive pkt, interval = 2
+1 ~ +3 > . 0:0(0) ack 1
// get no response, send rst
+1 ~ +3 > R. 1:1(0) ack 1
+1 read(4, ..., 10) = -1 ETIMEDOUT (Connection timed out)
+0 close(4) = 0
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