TCP Spurious Retransmission
Could someone explain to me what's going on in this tcp dump ?
5 13:02:12.985389 5.5.5.5 1.2.3.4 TCP 74 57464 → 12345 [SYN] Seq=0 Win=29200 Len=0 MSS=1460 SACK_PERM=1 TSval=2535707980 TSecr=0 WS=128
6 13:02:12.985411 1.2.3.4 5.5.5.5 TCP 74 12345 → 57464 [SYN, ACK] Seq=0 Ack=1 Win=28960 Len=0 MSS=1460 SACK_PERM=1 TSval=1516508357 TSecr=2535707980 WS=1024
7 13:02:13.183362 5.5.5.5 1.2.3.4 TCP 66 57464 → 12345 [ACK] Seq=1 Ack=1 Win=29312 Len=0 TSval=2535708030 TSecr=1516508357
8 13:02:13.183806 5.5.5.5 1.2.3.4 TCP 66 57464 → 12345 [FIN, ACK] Seq=1 Ack=1 Win=29312 Len=0 TSval=2535708030 TSecr=1516508357
9 13:02:13.682592 5.5.5.5 1.2.3.4 TCP 66 [TCP Spurious Retransmission] 57464 → 12345 [FIN, ACK] Seq=1 Ack=1 Win=29312 Len=0 TSval=2535708155 TSecr=1516508357
10 13:02:13.982144 1.2.3.4 5.5.5.5 TCP 74 [TCP Spurious Retransmission] 12345 → 57464 [SYN, ACK] Seq=0 Ack=1 Win=28960 Len=0 MSS=1460 SACK_PERM=1 TSval=1516508607 TSecr=2535708155 WS=1024
11 13:02:14.180635 5.5.5.5 1.2.3.4 TCP 66 [TCP Dup ACK 7#1] 57464 → 12345 [ACK] Seq=2 Ack=1 Win=29312 Len=0 TSval=2535708279 TSecr=1516508357
14 13:02:14.285845 5.5.5.5 1.2.3.4 TCP 66 [TCP Spurious Retransmission] 57464 → 12345 [FIN, ACK] Seq=1 Ack=1 Win=29312 Len=0 TSval=2535708305 TSecr=1516508357
21 13:02:15.487487 5.5.5.5 1.2.3.4 TCP 66 [TCP Spurious Retransmission] 57464 → 12345 [FIN, ACK] Seq=1 Ack=1 Win=29312 Len=0 TSval=2535708606 TSecr=1516508357
25 13:02:17.894558 5.5.5.5 1.2.3.4 TCP 66 [TCP Spurious Retransmission] 57464 → 12345 [FIN, ACK] Seq=1 Ack=1 Win=29312 Len=0 TSval=2535709208 TSecr=1516508357
26 13:02:17.894580 1.2.3.4 5.5.5.5 TCP 54 12345 → 57464 [RST] Seq=1 Win=0 Len=0
Can you provide the packet capture? See https://blog.packet-foo.com/2016/11/t... if you need to sanitize the packets first.