We're experiencing som extremely weird networking problems at our
office, now I know this (probably) isn't a Checkpoint related problem,
but I'm trying this mailing list in order to get an idea of what to do
next, or which forums/web sites/mailing lists I really should direct my
request at, since I haven't found any dedicated, *good* networking
forums on Google.

Here is the problem:
Last Friday morning, I was unable to SSH into the Sun servers at our
office, the SSH client just hung at connecting. It worked as normal
Thursday evening when we left so I thought this was a Windows problem,
but after rebooting the laptop as well as another employee complained
about the same problem, it turned out there's something weird going on
with our network.

What happens is this:

1: (Everything is on the same subnet, behind a Nokia IP-330 NG AI
firewall. The switch is layer 2 so it doesn't route anything. No
configuration has been changed on the switch, the firewall, servers or
office PC's)

2: We can SSH into 1 of 4 Sun servers

3: ALL servers are reachable by FTP, ping and HTTP (not tried anything
else, but enabled Telnet once and it produced the exact same result,
i.e. hung), but not SSH

4: What turns up in var/adm/messages when we try SSH is this:
"Apr 18 10:04:29 jupiter sshd[15028]: [ID 800047 auth.crit] fatal:
Timeout before authentication for x.x.x.x" - to me indicating that the
packet and response from the servers *seems* to be routed somewhere else

5: If we use SSH from our 3 remote production sites which are on the
same VPN or even using a
remote PC with SecureClient, we can reach these servers with no problems
whatsoever

6: We can SSH from one server to the other between these 3, we can even
SSH into the fourth server from these 3, (the latter is also the only
one reachable from our office PC's with SSH), but SSH from this fourth
server hangs to the other 3

7: Using SmartTracker I can't see any log captured SSH packets, so
everything seems to be going on locally on the switch/backbone, not
going via the gateway at all

8: I've rebooted the switch twice, I even rebooted the servers *and* the
firewall and the problem still persists

9: I unplugged every cable from the switch one by one, while another
employee tried SSH into a server. SSH failed every single time

10: I replaced the switch this morning with an identical model and
configuration, but the problem still persists

11: On 2 of 3 servers I can sometimes get lucky and a SSH session is
successfully established -- after a looooong time. None of the other
employees gets an established session

12: SSH to the firewall and a Linux box on the same subnet works
perfectly

13: Just poking around I tried route -f on one of the servers. I was
able to SSH into it every single time, but still none of the other
employees were. Of course the gateway address disappeared with the route
flushed. After a reboot the server went back to "normal" and I was
unable to SSH into it again

14: This happens with SecureSSH (4.1/5.0), Putty and OpenSSH (various
versions) installed on the servers

So that's it, I've tried about everything I can think of, but use a
packet sniffer, even though I'm not sure if it will produce any results.
I do suspect this to be a routing issue even though I can't see any
'mal-routed' packets on the firewall.

Has anyone an idea of what I can try next, or perhaps provide me with a
link to some networking forum where I can ask about this? Or, which
syntax is correct for fw monitor -e - I want to use source/destination
server/my laptop for SSH in order to see if any packets are routed
externally for some reason. Would 'fw monitor -e 'src=server;' AND
'dst=laptop' be correct?

--

Stig Bull
Networking and Systems Administrator
Hugin ASA
http://www.hugincorporate.com
Phone: +47 22 80 79 89 Mobile: +47 91 60 88 74 Fax: +47 22 80 79 79
- Your reputation connects through Hugin

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