Matthias Drochner writes:
> If it closes after about 2 hours and 12 minutes, then it
> is what I have fixed last week (tcp_subr.c rev. 1.71).
> The code for sending of keepalive messages (the m==0 case
> in tcp_respond) had 2 independant bugs which caused
> keepalive packets to be dropped silently.

No, that doesn't seem to be it.  I've also recompiled my kernel and
libraries a couple of times since then (with up to date sources), and
I get the same behaviour.

Here's an example of what I get in syslog if I connect to my box
(karybdis) and then leave it alone (i.e, don't type anything, etc).:

Jul 24 12:32:21 karybdis sshd[268]: log: Connection from 131.170.24.1 port 2618
Jul 24 12:32:22 karybdis sshd[268]: log: RSA authentication for lukem accepted.
Jul 24 14:32:25 karybdis sshd[268]: fatal: Read error from remote host: Connection timed out

The next step would be to run ssh in debugging mode and see what
happens.