wireshark shows: TCP Port numbers reused on PlanetLab nodes

[wen lui <esolvepolito () gmail com>]

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'?

___________________________________________________________________________
Sent via:    Wireshark-users mailing list <wireshark-users () wireshark org>
Archives:    http://www.wireshark.org/lists/wireshark-users
Unsubscribe: https://wireshark.org/mailman/options/wireshark-users
             mailto:wireshark-users-request () wireshark org?subject=unsubscribe