I'm having some very odd issues with my sshd. From time to time (at
random intervals) my ssh-connection will die with the following message:
Disconnecting: Timeout, server not responding.
in the beginning this only happened on remote connections, and never on
the internal network, so I suspected my adsl-router/nat-box. But the
other day it happened locally too. First time ever though. But usually
this is only an issue when connecting from remote sites. However it
varies. It works with no hassles from some places. Gets killed often on
the wireless connection at my university, but if I setup an ssh-session
in a screen on one of the university servers, it's never terminated this
way.
At work they have a strict proxy/fw setup. So I use this script:
http://wiki.tcl.tk/9411 to create a connection via the proxy to my sshd
on port 443 at home (or actually just on 22 with an iptables rule to
pickup connctions from that particular proxy on 443). through this
ssl/ssh-tunnel i direct the major part of my traffic, even a couple of
ssh-sessions to the server running the tunnel. Again this connection
will at random intervals get killed. So I suspected the proxy of
terminating the ssl-connection due to some time-limit, but the random
interval vouches against this.
The next suspect/device in line would be my dsl-router. However some
times the ssh-sessions going through the tunnel will get killed without
the session that actually serves the tunnel will die. As the other
connections are ssh-wrapped all the way to the sshd, this is the only
place the problem can really be isolated. Also as this happened once on
the internal network, I suspect something is borked with my sshd. I
upgraded my versions of sshd on both the server and my laptop who's
usually the client. Both run Linux(2.6.14.x) and the laptop is running
"OpenSSH_4.2p1, OpenSSL 0.9.7d 17 Mar 2004", the server "OpenSSH_4.2p1,
OpenSSL 0.9.7e 25 Oct 2004".
Also this is an issue (from some connections) for a friend of mine
(using my sshd) running openssh on openbsd, so it's clientwise platform
independent anyway.
To the best of my knowledge ssh -vvv gives nothing out of the ordinary
prior to the disconnects, but being home atm prevents me from provoking
this error, so I can't give the output here.
Also I have no issue connecting (and staying connected) to other sshds
from my laptop. My previous server never had this problem also using
openssh on Linux.
I've enabled {Server|Client}AliveInterval 1 on the respective laptop and
servers configs without any noticeable difference.
So I'm wondering what causes this issue. I'm out of ideas, and I'm
hoping some of you have tried this before or have some inputs.
Lasse Riis
