[CentOS] Ideas for stopping ssh brute force attacks

Ned Slider ned at unixmail.co.uk
Mon Jul 21 21:17:21 UTC 2008

Bo Lynch wrote:
> just wanted to get some feedback from the community. Over the last few
> days I have noticed my web server and email box have attempted to ssh'd to
> using weird names like admin,appuser,nobody,etc.... None of these are
> valid users. I know that I can block sshd all together with iptables but
> that will not work for us. I did a little research on google and found
> programs like sshguard and sshdfilter. Just wanted to know if anyone had
> any experience with anything like these programs or have any other advice.
> I really appreciate it.

There's a page on the Wiki with a few suggestions for hardening SSH:


There are a number of measures you can take and employing a few in 
combination is always a good idea. Strong passwords are a must as is 
disabling root logins. Firewalling and/or key-based authentication with 
passwords disabled are great where that is possible. Moving SSH to a 
non-standard port will certainly reduce your levels of background noise 
but doesn't necessarily make your setup inherently more secure.

My personal opinion is that there is enough there to work with without 
having to resort to 3rd party add-ons :)

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