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multiple SYN/ACK for one handshake
I have a question about the TCP handshake process.
Recently, I got an intermittent issue on my Openshift pod, below is the tcpdump. From the dump, what I can see is the server pod send back two SYN/ACK for one client SYN, the two SYN/ACK has different SEQ.
I have no idea about how the server returns different SEQ to the client, any one can help me with this? Thanks a lot!
276745 2021-12-13 14:40:59.693787 10.128.2.1 10.128.5.12 TCP 124 60028 → 8080 [SYN] Seq=0 Win=28200 Len=0 MSS=1410 SACK_PERM=1 TSval=1278780542 TSecr=0 WS=128
276747 2021-12-13 14:40:59.693926 10.128.5.12 10.128.2.1 TCP 124 8080 → 60028 [SYN, ACK] Seq=0 Ack=1 Win=27960 Len=0 MSS=1410 SACK_PERM=1 TSval=2347794832 TSecr=1278780542 WS=128
276748 2021-12-13 14:40:59.694005 10.128.5.12 10.128.2.1 TCP 124 [TCP Previous segment not captured] [TCP Port numbers reused] 8080 → 60028 [SYN, ACK] Seq=122 Ack=1 Win=27960 Len=0 MSS=1410 SACK_PERM=1 TSval=2347794832 TSecr=1278780542 WS=128
276749 2021-12-13 14:40:59.694131 10.128.2.1 10.128.5.12 TCP 116 60028 → 8080 [ACK] Seq=1 Ack=1 Win=28288 Len=0 TSval=1278780543 TSecr=2347794832
276750 2021-12-13 14:40:59.694167 10.128.2.1 10.128.5.12 HTTP 1674 POST /docker/sys/tipUpdate HTTP/1.0
276751 2021-12-13 14:40:59.694194 10.128.2.1 10.128.5.12 TCP 116 [TCP Dup ACK 276749#1] 60028 → 8080 [ACK] Seq=1559 Ack=1 Win=28288 Len=0 TSval=1278780543 TSecr=2347794832
No. Time Source Destination Protocol Length Info
276752 2021-12-13 14:40:59.694252 10.128.5.12 10.128.2.1 TCP 104 8080 → 60028 [RST] Seq=1 Win=0 Len=0
276753 2021-12-13 14:40:59.694326 10.128.5.12 10.128.2.1 TCP 104 8080 → 60028 [RST] Seq=1 Win=0 Len=0
276754 2021-12-13 14:40:59.694386 10.128.5.12 10.128.2.1 TCP 104 8080 → 60028 [RST] Seq=1 Win=0 Len=0
304998 2021-12-13 14:41:00.700469 10.128.5.12 10.128.2.1 TCP 124 [TCP Retransmission] [TCP Port numbers reused] 8080 → 60028 [SYN, ACK] Seq=122 Ack=1 Win=27960 Len=0 MSS=1410 SACK_PERM=1 TSval=2347795838 TSecr=1278780542 WS=128
305000 2021-12-13 14:41:00.700586 10.128.5.12 10.128.2.1 TCP 124 [TCP Retransmission] 8080 → 60028 [SYN, ACK] Seq=0 Ack=1 Win=27960 Len=0 MSS=1410 SACK_PERM=1 TSval=2347795838 TSecr=1278780542 WS=128
305001 2021-12-13 14:41:00.700730 10.128.2.1 10.128.5.12 TCP 104 60028 → 8080 [RST] Seq=1 Win=0 Len=0
305002 2021-12-13 14:41:00.700769 10.128.2.1 10.128.5.12 TCP 104 60028 → 8080 [RST] Seq=1 Win=0 Len=0
multiple SYN/ACK for one handshake
I have a question about the TCP handshake process.
Recently, I got an intermittent issue on my Openshift pod, below is the tcpdump. From the dump, what I can see is the server pod send back two SYN/ACK for one client SYN, the two SYN/ACK has different SEQ.
I have no idea about how the server returns different SEQ to the client, any one can help me with this? Thanks a lot!