Art of Information Security

Quick update to Part 2 of the AoIS Secure Your Linux Host Series on SSH.

I noticed a great article today on  Xavier Mertens‘ /dev/random blog (which by the way has several great posts that have caught my eye…), on SSH tunneling -> “Keep an Eye on SSH Forwarding“.

In addition to providing a solid introudction to SSH Port Forwarding Xavier also discusses:

• Using SSH as a SOCKS Proxy via the SSH Server
• Logging port forwarding
• Restricting  ports that can be forwarded

Check it out.

Cheers, Erik

Two Quick updates to Part 2 of the AoIS Secure Your Linux Host Series on SSH.

Interesting Series by ISS X-Force on SSH

Just this morning I ran across a three part series on SSH published last year in IBM’s Internet Security Systems X-Force Threat Insight in the following issues:

• X-Force Threat Insight Monthly – April 2008
• X-Force Threat Insight Monthly – May 2008
• X-Force Threat Insight Monthly – June 2008

X-Force expresses a slightly different set of concerns, and solutions. One topic that I did not touch on was the use of ssh agents for the management of sessions. Part 3 (June) is almost entirely focused on that.

Logwatch Samples

One of the great things about the script kiddies is they are keep testing your security for you ! Below is a mash-up and edit-down of the last few days of ssh related itms from my logwatch logs. Logwatch really has become one of my favorite tools. I don’t have tons of attacks on my servers, but there is always enough activity in the logs to let me know that the controls and countermeasures are up and running. After installing fail2ban, I always have some activity in 24 hour period of time. 

And a tip for the paranoid – if you have Failed logins and Illegal users but no fail2ban activity – then fail2ban has stopped running (or worse…).

——————— fail2ban-messages Begin ————————
Banned services with Fail2Ban:
Bans:Unbans  
ssh: [ 6:6 ]  
ssh: [ 4:7 ]  
ssh: [ 6:5 ]
ssh: [ 5:3 ]
———————- fail2ban-messages End ————————-

——————— SSHD Begin ————————
Failed logins from:
75.xxx.109.82 (75-xxx-109-82-Indianapolis.hfc.comcastbusiness.net): 1 time
79.xxx.248.27 (host27-xxx-static.38-79-b.business.telecomitalia.it): 1 time
200.xxx.209.156 (dedint-200-xx-209-156.mexdf.axtel.net): 3 times
59.xxx.92.26: 6 times
88.xxx.16.23 (…): 7 times
119.xxx.154.57: 6 times
203.xxx.198.3 (…): 6 times

Illegal users from:
60.xxx.249.90 (…): 3 times
75.xxx.109.82 (…): 3 times
79.xxx.248.27 (…): 3 times
200.xxx.209.156 (…): 2 times
202.xxx.28.244 (…): 3 times
85.xxx.133.177: 4 times
193.xxx.161.136: 4 times
———————- SSHD End ————————-

Cheers, Erik