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Old 10-03-2013, 01:23 PM   #1
mddnix
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sshd debug mode


Hi All,

Server: CentOS 6.4 x86_64
Client: Ubuntu 13.04

I was trying SFTP Chroot Jail, and while doing so, i ran into some problems. So i wanted to debug ssh connection - to know why i am not able to connect? In the end, i solved the problem. But while searching internet on how to debug sshd, i came across many tutorials like this one 'How can I run Openssh daemon in debug mode?'.

But i am not getting any debug messages at all.

This is what i did: (Pls see attached ScreenShot)
  1. (Left-Top): On Server, issued command '/usr/sbin/sshd -p 12345 -D -d -e', to start ssh daemon in debug mode.
  2. (Left-Bottom): From client, ssh to server as wrong user and also as correct user. I was hoping that debug messages will scroll up on server monitor. But nothing happened... not even cursor moved.
  3. (Right): So, to verify, i opened /var/log/secure file, and everything seems fine. all the right noises are made.

What i'm doing wrong? Am i wrong that i am expecting some messages will scroll on server monitor in debug mode? Where are debug messages shown...

Any help will be much appreciated.

Thanks
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Old 10-03-2013, 01:30 PM   #2
jpollard
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Looks to me like you forgot to specify the port in the ssh connection (-p 12345 on the ssh command)
 
Old 10-03-2013, 01:42 PM   #3
mddnix
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Quote:
Originally Posted by jpollard View Post
Looks to me like you forgot to specify the port in the ssh connection (-p 12345 on the ssh command)
I did try. but it throws error.
Code:
$ ssh -p 12345 madhu@cent
ssh: connect to host cent port 12345: No route to host

$ ssh -p 12345 madhu@192.168.1.50
ssh: connect to host 192.168.1.50 port 12345: No route to host
But if you look at '/var/log/secure' file (right-window), i'm getting response. all three windows are in real-time.
 
Old 10-03-2013, 04:24 PM   #4
jpollard
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IN the past, when I've done this, sshd does not log to anything but the terminal running sshd in the debug mode.

All the others are using the default port, therefore I would expect those are from the ssh without the port specification.

It is possible for a router/firewall to be blocking access to port 12345 (I have seen some reports where it happens).
 
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Old 10-03-2013, 04:32 PM   #5
corp769
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+1 to jpollard's post; I had nearly the same exact issue arise on me about two weeks ago, and my firewall on my network was at fault the whole time. Tip: When you are using odd port numbers for ssh, remember to account for that in your firewall
 
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Old 10-03-2013, 04:56 PM   #6
mddnix
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Quote:
Originally Posted by jpollard View Post
It is possible for a router/firewall to be blocking access to port 12345 (I have seen some reports where it happens).
You hit the bull's-eye!!! As corp769 also mentioned, it was iptables blocking it. Stopped iptables to check - Bhoom... server teminal started talking...

Thanks-a-lot
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Old 10-03-2013, 04:59 PM   #7
corp769
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I'm actually quite happy I replied to that post! ... I forgot to finish that server, so I got up off my lazy @ss and finished it. Cheers?

And kudos on getting that working!
 
  


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