Antivirus and firewall

I am using Asterisk at home (Asterisk 1.2.7.1) it is on centOS4.3(final). I’m not very familiar with Linux and I’ve kinda been thrown into administrating this system. My question is, Does this OS / application have somesort of antivirus/firewall in place or do I need to install something? If I do need to install something, does anyone have some suggestions?

Thanks so much!

Troy

Most of linux distro comes with iptables installed (if not you will need to recompiled the kernel) and since CentOS is a RedHat based distro im sure that iptables will be installed. Just try to do iptables -L as root and you will see if there are any rules already in place.
For a intrusion detection snort is a free one and a good one (www.snort.org). and the best way to update snort rules is oinkmaster (search it in google !)
And you don’t really need an antivirus on linux !