ClearOS is a gateway firewall that can be simple to install and configure with some basic understanding of networking, however it can be as meticulous as you need it to be as well.
This Linux distro is also very flexible, ClearOS can host websites, email, media server and that's to say the least.
On the security end, ClearOS has a lot to offer with Intrusion detection rules coming from "emerging-threats", content filtering and many others to secure your network.
Post questions or add info about ClearOS in this area of the forum. Read more about ClearOS here