[XDMCP] XDM/KDM sometimes not responding to UDP packets on port 177

Discussion in 'Linux Networking' started by Marcel Meckel, Apr 25, 2005.

  1. Hi,

    short introduction:

    -Linux terminal server serving xdm/kdm login manager via XDMCP
    to X (thin)clients over ethernet
    -Clients are thinclients and normal x86 PCs running x.org

    problem:

    from time to time the login manager (xdm and kdm are both affected)
    serving on the terminal server stops reading from it's received packets
    queue leading to not being able to login remotely via XDMCP.

    packet flow when all is fine:

    client -> server:177/udp
    server -> client "Willing to serve"

    packet flow when the mentioned problem occurs:

    client -> server:177/udp (no response, some seconds delay)
    client -> server:177/udp (no response, some seconds delay)
    client -> server:177/udp (no response, some seconds delay)
    ....

    # netstat -lnp (server)
    Active Internet connections (only servers)
    Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program
    udp 2800 0 0.0.0.0:177 0.0.0.0:* 2567/kdm

    The size of the Recv-Q is growing accordingly to udp packets received
    from clients.

    Client and server are in the same subnet, no bridge or router in
    between.

    Server is running X.org 6.8.2, kernel 2.6.11.

    Sidenote: A kill `pidof kdm` doesn't kill kdm, kill -9 is needed.

    I'm a bit frustrated since googling around didn't give me much info what
    could be wrong here. I would be glad if someone could point me in the
    right direction.

    X-Post & F'up2 comp.os.linux.networking

    Greetings,
    Marcel.
     
    Marcel Meckel, Apr 25, 2005
    #1
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  2. Marcel Meckel, Apr 26, 2005
    #2
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