Please Help! How to STOP them...

[Reko Turja]

From: "VeeJay" <maanjee at gmail.com>
To: <maanjee at gmail.com>; "FreeBSD-Questions" 
<freebsd-questions at freebsd.org>
Sent: Friday, January 12, 2007 11:43 PM
Subject: Please Help! How to STOP them...


>I am reading many hundred lines similar to below mentioned?
>
> Could you please advise me what to do and how can I make my box more 
> secure?
>
> Jan  9 17:54:42 localhost sshd[5130]: reverse mapping checking 
> getaddrinfo
> for bbs-83-179.189.218.on-nets.com [218.189.179.83] failed - 
> POSSIBLE
> BREAK-IN ATTEMPT!
> Jan  9 17:54:42 localhost sshd[5130]: Invalid user sysadmin from
> 218.189.179.83

It's basically just script kiddies trying to get in using some ready 
made user/password pairs.

Lots of info covering this has been posted in these newsgroups 
previously, but some things you might consider

Moving your sshd port somewhere else than 22 - the prepackaged 
"cracking" programs don't scan ports, just blindly try out the default 
port - with determined/skilled attacker it's different matter entirely 
though.

Use some kind of portblocker (lots in ports tree) which closes the 
port after predetermined number of attempts - or as an alternative, 
use PF to close the port for IP's in question after predetermined 
number of connection attempts in given time.

Use key based authentication and stop using passwords altogether.

Remember to keep ssh1 disabled as well as direct root access into ssh 
from the ssh config file.

-Reko