Here are some of the tools we use to monitor networks and provide security. We believe in Open Source tools, and use them here at linuxforbusiness.net. These tools are especially useful:

An Intrusion Detection Systems (IDS) is a vital piece of network security. The SANS (System Administration, Networking, and Security) Institute is a great reference source for IDS information. Click here to go to their IDS page.

SNORT is the IDS in place at linuxforbusiness.net. It is an Open Source application that can be configured to log intrusion attempts that get past your firewall. We can often use these logs to track an intrusion attempt back to its source. This is the home page of SNORT.

Netfilter is an Open Source firewall system. It is the new firewall system deployed in Redhat 7.2 which uses the userland application iptables. It is very flexible, and can be configured to provide high security. Read more about netfilter here.