antivirus/firewall
 

Do I need a antivirus/firewall if so are there any open source ones?

If you are serving Microsoft boxes and want to protect them, yes.

# Linux and virus
The Virus Writing HOWTO reference: Should I get anti-virus software for my Linux box?

# Basic Linux security
Linux Questions Security references
Security Help Files
Linux Administrator's Security Guide
Security Focus
Linux Security
Firewalls and Security