[CentOS] Program to ban sniffers

> I doubt there is a program like this, but I would love to have a program
> that listens at common ports that I do not use at all...and only allow that
> program to listen to it, especially the usual ssh port (using a different
> one for real ssh)...
>
> That program would then, upon receiving a 'sniff' or 'user' would then add
> that ip to the deny hosts lists..for either a long or short time.

Many years ago I used portsentry for this.  You can find an article about 
portsentry at <http://www.securityfocus.com/infocus/1580>

Barry