weird ssh problem [SOLVED]

[petersk]

I am running a new installation of Kubuntu on one of my machines, let's call it machine "X".
I have identical sshd_config files on both machines. I can log in to machine Y from machine X, but not vice versa. I've tried changing the port to 222 instead of 22, and still nothing. I'm running ufw on both and have done a ufw accept 222 and 22 on both.

I can connect from machine X to machine X, no problem. I can also connect from machine Y to other machines. It just looks like somehow my new machine is somehow blocking incoming ssh 's from other machines (once again, it accepts an 'ssh 127.0.0.1' no problem.

Does anyone know what I'm not configuring right on the new install?
Kurt

[hteles]

Re: weird ssh problem

Hi,

could you please nmap machine X from Y.

[flarson]

Re: weird ssh problem

What shows up in /var/log/auth.log on X when you try to ssh to it?

[petersk]

Re: weird ssh problem

absolutely nothing in auth.log.
May 10 20:30:49 loki sshd[2556]: Server listening on 0.0.0.0 port 222.
May 10 20:30:49 loki sshd[2556]: Server listening on :: port 222.


The connection times out on my other machine too.
when I do a -vv on that one it says "debug2: ssh_connect: needpriv 0" I'm not sure if that's important

I've even tried:
sudo iptables -P INPUT ACCEPT
sudo iptables -P OUTPUT ACCEPT
sudo iptables -P FORWARD ACCEPT

sudo iptables -F # Comment (flushes all existing iptables chains)

to ensure it isn't a firewall problem.


Can you provide an example of how I'd use nmap?

I found this message with a guy with a similar problem, but he never tells how he solved it as far as I can tell: https://lists.ubuntu.com/archives/ub...er/159532.html

[petersk]

Re: weird ssh problem

OK, I did a apt-get remove --purge ufw, and then removed /etc/rc.firewall and anything referencing guarddog or ufw in all my rc[1-5].d directories. This was prompted because nmap couldn't see anything on my machine that I wanted to connect to from the other machine. And when I did nmap to the machine that wasn't allowed to connect, it wouldn't show 222 as being open despite my ufw'ing accept 222 on it and ufw status showing it open. That's what led me to just remove ufw and all other traces of firewalls to be "safe", with the debug anyways.
This at least let me see a response from my ssh which recognized that the fingerprint in my "knownhosts" had changed. After deleting that file, I could now connect to the machine.... Thanks for your help -- I guess that is a hazard of going and doing a full system reinstall, instead of just "upgrading".... Of course, my upgrade failed and locked my machine up, which is the reason I had to reinstall from scratch. :-|


Now to "reinstall" ufw and set that back up to see what happens.

Thanks for the nmap suggestion... Seems like a useful tool.
Kurt

[hteles]

Re: weird ssh problem

Hi,

glad that you make it.

maybe there were some conflicting firewall rule over there.

You better choose one of them, ufw or guardog.

Best wishes

[toad]

Re: weird ssh problem

And because this thread is useful to all concerned we encourage people to mark solved threads as SOLVED Instructions on how to do that are in my signature - and yes, nmap is cool