SSH connection problem
Steven Borrelli
I am relatively new to configuring SSH.. I use it a lot, every day in
fact.
I am having a problem with SSH on my FreeBSD system. I think it is
FreeBSD version 4.2 or 4.8, I can't remember. And the SSH version is
whatever came with FreeBSD by default. Also, Squid 2.4 STABLE 12
(caching proxy) is set up on the system.
>From a Windows system outside of the network (using PuTTy), I can
connect through port 22 to the server, but it doesn't even give me a
chance to login. The error message goes as follows:
ssh_exchange_identification: Connection closed by remote host
The network design is just a T1 coming in, a Cisco router, the FreeBSD
box with two ethernet cards (one for internal, one for external), and
then two hubs with about fifteen Windows machines connected.
>From inside the network, I cannot even establish a connection through
SSH. It's almost like the proxy is blocking it, but I can't see any
signs of that in the proxy's configuration file.
Any ideas as to how to fix the problem with SSH?
Richard E. Silverman
SB> Hi everyone... I am relatively new to configuring SSH.. I use it
SB> a lot, every day in fact.
SB> I am having a problem with SSH on my FreeBSD system. I think it
SB> is FreeBSD version 4.2 or 4.8, I can't remember. And the SSH
SB> version is whatever came with FreeBSD by default. Also, Squid 2.4
SB> STABLE 12 (caching proxy) is set up on the system.
>> From a Windows system outside of the network (using PuTTy), I can
SB> connect through port 22 to the server, but it doesn't even give me
SB> a chance to login. The error message goes as follows:
SB> ssh_exchange_identification: Connection closed by remote host
This often means your libwrap settings (/etc/hosts.{allow,deny}) are
denying the connection.
SB> The network design is just a T1 coming in, a Cisco router, the
SB> FreeBSD box with two ethernet cards (one for internal, one for
SB> external), and then two hubs with about fifteen Windows machines
SB> connected.
>> From inside the network, I cannot even establish a connection
>> through
SB> SSH. It's almost like the proxy is blocking it, but I can't see
SB> any signs of that in the proxy's configuration file.
SB> Any ideas as to how to fix the problem with SSH?
--
Richard Silverman
r...@qoxp.net
Steven Mocking
> ssh_exchange_identification: Connection closed by remote host
This could be a whole range of problems. What does the server log report
for your login? Does the same thing happen when you ssh to localhost on
the server?
Steven Borrelli
I can ssh to localhost just fine.. there's no problem with that.
It's just the remote connections i'm having trouble with. And it
appears to be that way for all user accounts on the system. I'm not
able to check the error logs at the moment... I'll get back with you
on that.
Nico
That sounds like a network or firewall problem. Definitely telnet to
port 22 from the client and see what happens.
Richard E. Silverman
NK> On 1 Sep, 17:46, Steven Borrelli <sborrel...@gmail.com> wrote:
>> On Sep 1, 6:39 am, Steven Mocking
>>
>> <u...@youmightwanttogetridofthis.quicknet.nl> wrote:
>> > Steven Borrelli schreef:
>>
>> > > ssh_exchange_identification: Connection closed by remote host
>>
>> > This could be a whole range of problems. What does the server log
>> report > for your login? Does the same thing happen when you ssh to
>> localhost on > the server?
>>
>> I can ssh to localhost just fine.. there's no problem with that.
>> It's just the remote connections i'm having trouble with. And it
>> appears to be that way for all user accounts on the system. I'm
>> not able to check the error logs at the moment... I'll get back
>> with you on that.
NK> That sounds like a network or firewall problem. Definitely telnet
NK> to port 22 from the client and see what happens.
Did you check check your libwrap control files, as I suggested earlier?
As I said, that's usually the cause of this problem.
--
Richard Silverman
r...@qoxp.net
Steven Mocking
The tcp wrapper problems Richard describes are very likely the cause if
it reacts different depending on the client host.
Also check if you have installed something like denyhost for blocking
automated login attempts. I've found that denyhost in particular has/had
(at least in june 2006) a very overzealous default configuration and
blocks ip addresses from SSH after a few typo's. You might want to look
at /etc/denyhosts.conf if it's installed.
Steven Borrelli
Sorry guys, I haven't had a chance to check any of these things
lately...
My thoughts are that nothing has been changed by anyone in the last
two years. In that time frame, we did have some lightning damage to
the router and some other things requiring the server to be rebooted.
Could there be something that was not set to start automatically upon
boot?
ssh was working perfectly two years ago. No one has even touched this
machine since then -- except me, starting a few months ago (unless we
got hacked...?). ssh has never worked properly for as long as I have
been working on the machine.
I'll check the logs soon.
Steven Borrelli
>
> - Show quoted text -
Hey now it works!
All I did was a kill -HUP [sshd's pid] and it started working. I
have no idea what was wrong with it, but it's all good now. I don't
think it had anything to do with the /etc/hosts.{allow/deny} or
anything. This being the case, any thoughts as to why it wasn't
working before?