Wireshark-users: [Wireshark-users] wireshark shows: TCP Port numbers reused on PlanetLab nodes
From: wen lui <esolvepolito@xxxxxxxxx>
Date: Wed, 20 Mar 2013 14:18:27 +0100
I run a simple TCP client on machine A and a simple TCP server on machine B (machine B is a Planetlab node while machine A is not).
Then the client establishes a tcp connection with machine B and send some data.
I capture packets on both A and B, on A the wireshark shows that it is a normal 3-Way handshaking, but on B, it shows as below:


1	0.000000	138.46.116.22	138.46.201.109	TCP	74	54000 > 57182 [SYN, ACK] Seq=0 Ack=0 Win=5792 Len=0 MSS=1460 SACK_PERM=1 TSval=1751648211 TSecr=1119925943 WS=128 0.000000
2 -0.000062 138.46.201.109 138.46.116.22 TCP 74 [TCP Port numbers reused] 57182 > 54000 [SYN] Seq=0 Win=14600 Len=0 MSS=1460 SACK_PERM=1 TSval=1119925943 TSecr=0 WS=128 -0.000062
3 0.000308 138.46.201.109 138.46.116.22 TCP 66 57181 > 54000 [ACK] Seq=1 Ack=1 Win=14720 Len=0 TSval=1119737278 TSecr=1751459556 0.000308

while I see on machine B, actually the tcp connection is established. before the client sends the SYN and ACK, I checked machine B and found no TCP connection

netstat -tnp (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) Active Internet connections (w/o servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 138.46.116.22:54000 138.46.201.109:57181 ESTABLISHED 17879/tcp_server

anyway, I can send data to the tcp server and it receives it correctly.

why wireshark shows TCP Port numbers reused? and the time is '-0.000062'?