Have I been hacked?

["Ed Lazor" <osmosis atfantasy com>]

I suspect that I've been hacked.  I found a directory titled "ADMROCKS" in
/var/named owned by root and I know that I didn't create it.  Does anyone
recognize this?

Any recommendations / advice on how to move forward?  I have RedHat 6.1 and
all of the latest updates on the system.  My guess is that I'll need to
rebuild the system.  Of course, there's no way for me to know if the hacker
can just break right back in after I do that.  I also figure I need to setup
a firewall.  Any recommendations on that?  Ie. firewall software to use,
related URLs, etc.

Thanks =)

-Ed