Hi Kevin,

I used the iptables recent module to help stop ssh brute force attacks

iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --set
--name SSH -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -m recent --update --seconds 60
--hitcount 4 --rttl --name SSH -j LOG --log-prefix "SSH_brute_force "
iptables -A INPUT -p tcp --dport 22 -m recent --update --seconds 60
--hitcount 4 --rttl --name SSH -j DROP

You can also include an ssh whitelist for servers you know are okay. This
method does have some caveats, but I found it very effective.

If you Google "ssh brute force" you'll find a tonne of solutions to this



"Zembower, Kevin"
Sent by: listbounce@securityfocus.com
10/07/2008 12:55 AM



Deliberately create slow SSH response?

This might seem like a strange question to ask, but is there a way to
deliberately create a slow response to an SSH request? I'm annoyed at
the large number of distributed SSH brute-force attacks on a server I
administer, trying to guess the password for 'root' and other accounts.
I think that my server is pretty secure; doesn't allow root to log in
through SSH, only a restricted number of accounts are allowed SSH
access, with I think pretty good passwords. But still, the attempts
annoy me.

I wouldn't mind if SSH took say 30 seconds to ask me for my password.
This would slow the attempts. Is there any way to configure OpenSSH to
do this? I searched the archives of this group with 'slow' and 'delay'
but didn't come up with anything on this topic. Please point it out to
me if I overlooked anything. In addition, I can limit the number of SSH
connections to 3-5 and still operate okay.

Ultimately, I need this solution for hosts running OpenSSH_3.9p1 under
RHEL ES 4 and OpenSSH_4.3p2 under Debian 'etch' 4.0 and Fedora Core 6.

Thanks in advance for your advice and suggestions.


Kevin Zembower
Internet Services Group manager
Center for Communication Programs
Bloomberg School of Public Health
Johns Hopkins University
111 Market Place, Suite 310
Baltimore, Maryland 21202