Hung ssh client connection

[Damien Mascord]

Hi guys,

I am running with: "OpenSSH_3.9p1 Debian-1ubuntu2, OpenSSL 0.9.7e 25 Oct
2004", as an ssh client, and am having some strange behaviour with a
firewall of ours.

We have a netscreen 5gt-plus, running ScreenOS 5.0.2, which has an ssh
daemon running.

I ssh to the firewall using `ssh username@<ip address>`, which works
correctly (ie, connects, and I can use the console of the firewall).

If I restart the firewall using the command 'reset', I get a message
that the firewall is resetting, which is good.

Now, the SSH client is hung, CTRL-C, CTRL-Z, CTRL-] don't do anything at
all.

Attaching strace:

root@<hostname>:~ # strace -p 28530
Process 28530 attached - interrupt to quit
select(7, [3 4], [], NULL, NULL <


It seems to be sitting there waiting for keyboard input, so as a last
resort, I try CTRL-~ which then disconnects (with a time out)!

Read from remote host <ip address>: Connection timed out
Connection to <ip address> closed.

What could be the cause of this connection 'hanging' ? Is it on the SSH
client, the SSH server not closing the connection correctly upon reset ?
 Or could it be something in the TCP OS layer ?

If it is expected behaviour, I apologize, though would like to
understand why this is happening on a technical level.

I am running:
# uname -a
Linux packrat 2.6.10-5-686-smp #1 SMP Tue Jun 7 09:34:54 UTC 2005 i686
GNU/Linux

which comes with glibc-2.3.2

Thanks in advance,

Damien