[ILUG] Accessing SSH remotely.

[Darragh]

Thanks for your response.  
On Sat, 2007-04-21 at 15:26 +0100, Gavin McCullagh wrote:
> Hi,
> 
> On Sat, 21 Apr 2007, Darragh wrote:
> 
> > One thing that did cross my mind is that nmap is actually passing
> > through the router and it's the linux box that's stopping port 22.  
> 
> It might be of use to figure out exactly where the packet stops.  If you
> run 
> 	tcptraceroute w.x.y.z 80
> 	tcptraceroute w.x.y.z 22
> 
> you should see them both take the same route and at the last hop you'll see
> [open] and [closed] respoectively (you probably won't see a hop from your
> router to FC6).  You can simultaneously run tcpdump on the FC6 machine:
> 
> 	tcpdump -i eth0 port 80
> 	tcpdump -i eth0 port 22
> 
> If the packets are reaching FC6, you'll see it on tcpdump.  If not, the
> router is either blocking them or forwarding them incorrectly -- it's
> possible it forwards them to some other address on your lan and that
> machine refuses the connection.
> 
> If you can't use tcptraceroute you can probably get most of the way just
> using telnet, though if there were some sort of filtering happening on port
> 22 further up (seems unlikely), the tcptraceroute would show it.   I guess
> you have verified that you can ssh from your external box to other hosts.
> 
> > I've turned off the firewall on the linux box temporarily to see if that
> > made any difference but as you can probably guess, it didn't.  Is there
> > something else that could be causing this?  Anything
> > in /etc/ssh/sshd_config or any of the other config files in that
> > directory?  What about SELinux? Could that be causing a problem?
> 
> What error does ssh actually give you?  For example, if it's an
> ssh_exchange_identification error, you probably have ssh blocked in
> /etc.hosts.{allow,deny}.
> 
> As Niall says, it sounds like a router issue.
> 
> Gavin
> 

Thanks for your help.

Yes.  it seems to be a router issue.  host unreachable is the error I'm
getting on the client side.

I've tried the tcpdump. it shows the connections when I'm connecting
from a computer inside the network but nothing is shown if I try
connecting from a computer not on this network which would lead me to
believe that it's a router issue.  

Thanks for your help.

Looks like I'm going to have to figure out what is wrong with this
router.