tcp ports ftp hangs in CLOSE_WAIT state with NMAP scanner - VxWorks

This is a discussion on tcp ports ftp hangs in CLOSE_WAIT state with NMAP scanner - VxWorks ; I have been using NMAP to scan all the open ports on my equipment which runs VxWorks Version 5.3.1. The scanner some times causes hung CLOSE_WAITS on the FTP port 21. Eventually after 8 such CLOSE_WAIT connections, FTP server hangs. ...

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Thread: tcp ports ftp hangs in CLOSE_WAIT state with NMAP scanner

  1. tcp ports ftp hangs in CLOSE_WAIT state with NMAP scanner


    I have been using NMAP to scan all the open ports on my equipment
    which runs VxWorks Version 5.3.1. The scanner some times causes hung
    CLOSE_WAITS on the FTP port 21.
    Eventually after 8 such CLOSE_WAIT connections, FTP server hangs.

    I came across this posting:
    http://groups.google.com/group/comp....7a1f9ffd8b886c

    I'm seeing the same problem with my FTP server too. Whenever I run
    NMAP to
    scan the ports, my FTP server hangs with 8 connections in CLOSE_WAIT
    state.

    I could not find the fix for this problem.

    If you have come across the same problem or know the fix for this
    problem please let me know.

    Thanks in advance.


  2. Re: tcp ports ftp hangs in CLOSE_WAIT state with NMAP scanner


    On 9 Mar 2007, pawansun@gmail.com wrote:

    > I'm seeing the same problem with my FTP server too. Whenever I run
    > NMAP to scan the ports, my FTP server hangs with 8 connections in
    > CLOSE_WAIT state.


    You can reproduce the same thing on Linux, etc. However the amount of
    connections would likely be higher. If NMAP (or anything) cause a
    hanging CLOSE state, the TCP rfc say that this should remain in the
    CLOSE_WAIT state for six hours or something insane like that.

    You can increase the amount of sockets available. There might also be
    a "CLOSE_WAIT" timer variable that can be changed to not wait for the
    full close handshaking. I think that Windows might also perform a
    truncated CLOSE sequence.

    fwiw,
    Bill Pringlemeir.

    --
    My cousin is an agoraphobic homosexual, which makes it kind of hard
    for him to come out of the closet. - Bill Kelly

    vxWorks FAQ, "http://www.xs4all.nl/~borkhuis/vxworks/vxworks.html"

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