Does anyone understand tcpdump output?

Discussion in 'Linux Networking' started by Tim Sampson, Aug 15, 2003.

  1. Tim Sampson

    Tim Sampson Guest

    Hi

    I'm trying to figure out why a client PC can't connect to our MRP system. I
    have done some tcpdump testing, but I don't know enough about the output. It
    always produces something similar to the following before the client gives
    up. Can anyone explain all the R0:0(0) and nop,nop,sackOK type stuff? Does
    this output explain why it might be failing?

    12:05:30.749224 192.168.100.2.873 > 192.168.101.17.1831: F 545:545(0) ack
    866 win 6432 (DF)
    12:05:30.782964 192.168.101.17.1831 > 192.168.100.2.873: . ack 546 win 16016
    (DF)
    12:05:31.543809 192.168.100.2.32815 > 192.168.101.17.1832: S
    2868601612:2868601612(0) win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 0>
    (DF)
    12:05:31.584487 192.168.101.17.1832 > 192.168.100.2.32815: R 0:0(0) ack
    2868601613 win 0

    The 100 and 101 networks are connected via a VPN.

    TIA
    Tim
     
    Tim Sampson, Aug 15, 2003
    #1
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