add option to limit # of ssh conn / time

[GoogleCodeExporter]

To reduce brute force attacks on the sshd, add an option to configure
iptables so that no more than X connections to the sshd are allowed in an
interval. This needs to be done in such a way that good ssh sessions are
not terminated 

Original issue reported on code.google.com by kemen04@gmail.com on 27 Jun 2008 at 12:51