Gentoo Archives: gentoo-user

From: Alan McKinnon <alan.mckinnon@×××××.com>
To: gentoo-user@l.g.o
Subject: [gentoo-user] SSH sessions hanging in VPN
Date: Fri, 19 Mar 2010 20:41:42
1 Hi all,
3 Not really directly related to Gentoo except that the workstation where it
4 happens is a Gentoo machine :-)
6 Our VPN at work is a Juniper Secure Connect. I tend to have many konsole tabs
7 running ssh at one time, as well as IMAP connections to Exchange and several
8 browsers tabs to intranet sites. Occasionally, and apparently triggered
9 randomly[1], all existing ssh sessions freeze and never come back (even after
10 several hours). The connections are still up and do not die on the remote end.
11 Mail connections stay up and the browser tabs continue to work as well[2].
13 I know the ssh sessions are alive on the other end as I can immediately log in
14 in another konsole tab and that works just fine. Even after several hours the
15 first sshd process does not timeout (timeouts are enabled). So it would seem
16 that it's the return path going tits up. My next step is going to be running a
17 trace and tcpdump on one of those existing session next time it happens.
19 Meanwhile, and this is my real question, how would I go about sensibly
20 debugging this in a methodical manner? I'm going to have to get my security
21 guys and routing guys to investigate but they will need real information to
22 work with. Everything I can think of just reduces to throwing brown smelly
23 stuff at the wall and hoping some of it sticks.
27 [1] By randomly I mean sometimes 4 times a day, sometimes nothing for several
28 days. I have not seen a correlation to anything I'm doing that might trigger
29 it.
30 [2] This is expected as HTTP is sessionless.
32 --
33 alan dot mckinnon at gmail dot com


Subject Author
Re: [gentoo-user] SSH sessions hanging in VPN Neil Walker <neil@×××××××.nu>