graphical firewall
 

Anyone no of a graphical firewall that isn't so complicated like iptables is?

firestarter - GTK program for managing and observing your firewall
is the only GUI that I know of.

What distribution are you using? It'll be easier to give you answers that you can find in your distribution's repositories if we know which one you're using.

I'm not sure that there can be an answer to the question, as stated. The graphical utilities are just 'easy' front ends to iptables, so you still end up using iptables, although there will be an 'out of site, out of mind' effect.

When I tried, I couldn't find a graphical front end that I could get on with, so learning iptables was the easiest way forward, but I'm sure that most other people's mileage will vary (and I was messing around with multiple interfaces, and one thing that confused me with graphical stuff was that I usually couldn't work out which interface I was messing with at any one time - you probably don't have that problem).

Hopefully, someone else's answer will help you more!

Centos 5 and Centos 6

Firestarter. It use Gnome libraries so it's the natural fit for CentOS.

Alternatively, you could learn how to use SELinux, which is included with CentOS. It's not the easiest to learn, but it's valuable knowledge.

More about SE/Linux on CentOS: http://wiki.centos.org/HowTos/SELinux