Some questions about TCP MSS

Discussion in 'Linux Networking' started by paul, Nov 15, 2012.

  1. paul

    paul Guest


    - I know that each party advertises its MSS in its SYN segment,
    using a suitable option in the TCP header. Is this only possible at the
    beginning (ie when SYNs are echanged) or can the option be set in
    subsequent (non-SYN) segments?

    - Does Linux somehow expose the MSS of active TCP session to userspace
    somehow (/proc, or whatever)? I found nothing.

    paul, Nov 15, 2012
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  2. paul

    Rick Jones Guest

    No. The TCP MAXSEG option is defined to be at connection
    establishment only.
    getsockopt() with a TCP_MAXSEG option can be called against the socket
    by the application. The netperf benchmark does this.

    To what end do you wish to put the information?

    rick jones
    Rick Jones, Nov 18, 2012
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  3. paul

    paul Guest

    Ok, thanks.
    Just for my information. I thought it could be useful to have it from the
    output of such tools like conntrack which list many information about
    current session.
    paul, Nov 19, 2012
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