weird ssh or X problem

From: David Minor (minor_at_fusion.gat.com)
Date: 07/21/05

  • Next message: Ed Wilts: "Re: rpm -Fvh glibc* hanging" 
    To: redhat-list@redhat.com
Date: Wed, 20 Jul 2005 15:07:45 -0700

    My apologies if this has been addressed previously - I didn't see
    anything for it in the archives.

    We're in the process of upgrading to RedHat Enterprise version 4 and
    are seeing a strange ssh or X problem. We're using a vanilla install.
    The only change we've made is two variables in sshd_config - we've
    got the following variables uncommented: X11UseLocalhost no
    X11Forwarding yes.

    Here's what happens:

    1) User ssh's into remote machine (machine1.company.com) which is
    running the new version. Tries to run an X process, say xclock. User
    is told:

    Error: Can't open display: machine.company.com:10.0

    User keeps this session open.

    2) User opens a second ssh session to the same remote machine. Runs
    xclock - it works. On this second session the client has been handed
    the same display (machine1.company.com:10.0) as the first session.

    3) User goes back to first session. Now xclock works in that session
    also.

    4) If user logs out of second session, X stops working on first session.

    We see this behavior regardless of the ssh client used (we've tested
    Linux, OSX, HP-UX). It also doesn't matter if we use X forwarding on
    the client (via -X or -Y) either.

    Note that if a user doesn't have concurrent ssh sessions open, X
    never works.

    Further looking at it indicates that this *might* be an X problem?

    1) First connection to the machine (using ssh again). It's handed
    display 10. X does not work. Telnetting to localhost 6010 gives a
    "connection refused" message.

    2) Second connection to the machine (again using ssh). Handed the
    same display. X works. Telnetting to localhost 6010 now works. So
    there's something going on with the way ports are being opened.

    3) Also, the machine simply isn't listening on port 6000. Compare this:

    On the machine with the problem:
    machine1.domain.com: netstat -an | grep 6000
    machine1.domain.com: [nothing]

    a different machine running RHEL version 3:

    machine2.domain.com: netstat -an | grep 6000
    tcp 0 0 0.0.0.0:6000
    0.0.0.0:* LISTEN

    Anyone else see this problem or have any suggestions?? 

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  • Next message: Ed Wilts: "Re: rpm -Fvh glibc* hanging"

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