I have experience securing servers in mission critical environments such as airports. I am familiar with many different linux distributions. I have in the past installed linux systems to act as gateways/firewalls exposed to insecure networks.
I've experience with iptables and a little mod-security. Depending on what you mean by securing your linux system, I could have the project done from 1 day to 3 days. Can you be more specific? Secure it from what exactly? I'be been a Linux Admin for about a year now with a lot of networking under my belt as well. I'm trying to improve my repertoire and resume. Very interested in your project.