Re: Ssh hangs after authentication

From: Jayson Anderson (
Date: 08/24/05

  • Next message: "Preserving ONLY modification times & access times for "scp""
    To: Adam Kerrison <>
    Date: Wed, 24 Aug 2005 10:47:50 -0700

    Without thinking too heavily about the many possibilities, the very
    first thing that pops into mind after 'Authenticate properly and then
    hang', is DNS. Bolstered by the fact that different sources result in
    different outcomes (works or doesn't, correct ?)

    First think I'd check is the resolver on the host itself; how is it
    resolving against the sources from which login occurs promptly after
    authentication, versus how is it resolving the sources from which login
    does not occur promptly (if at all) after authentication.

    My apologies if this is painfully obvious or checked long ago, but if
    it's not DNS then [discontiguous, etc.] routing is a close runner-up...


    On Wed, 2005-08-24 at 09:16 +0100, Adam Kerrison wrote:
    > Hi
    > I'm having trouble with openssh when connecting from my Mac OS X (Tiger)
    > laptop at home to a Linux server in my office. When I'm in the office
    > everything works fine, when I'm at home the ssh connection just hangs.
    > I have an ADSL router at home which acts as a Firewall with NAT but I don't
    > believe the problem is there (see below). Also from home I have to use a
    > CiscoVPN but again I don't think that's the problem.
    > When I connect via ssh it hangs right after the authentication has succeed
    > and just before I would expect the shell prompt. Running ssh -vvv shows all
    > the authentication steps and ends with:
    > debug1: Authentication succeeded (publickey).
    > debug1: channel 0: new [client-session]
    > debug3: ssh_session2_open: channel_new: 0
    > debug2: channel 0: send open
    > debug1: Entering interactive session.
    > debug2: callback start
    > debug2: ssh_session2_setup: id 0
    > debug2: channel 0: request pty-req
    > debug3: tty_make_modes: ospeed 9600
    > debug3: tty_make_modes: ispeed 9600
    > debug3: tty_make_modes: < ... Lots of theses, snipped ... >
    > debug2: channel 0: request shell
    > debug2: fd 3 setting TCP_NODELAY
    > debug2: callback done
    > debug2: channel 0: open confirm rwindow 0 rmax 32768
    > At this point its dead. I have to kill the local ssh client or remote sshd.
    > I ran up an sshd in debug mode to try and find out what's happening but
    > there's nothing in the logs that would indicate a problem.
    > Now the final twist: If I use PuTTY from a Windows machine at home it works
    > fine. I have now downloaded and tried the Mac OS X version of PuTTY and that
    > also works!
    > Searching back through the mail list archives I've seen several other people
    > reporting the same or similar issue but no resolutions - does anyone know
    > what's going on here because I'm really stumped! I have saved all the logs
    > if anyone wants to dig deeper (they are large so I didn't want to include
    > them) and I can run up test daemons etc.
    > Sorry for the long post ...
    > Adam K


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