Summary An explanation of firewalls, types of firewalls, stateless vs stateful filtering, placement of firewalls within a network, examples of firewall rules, and the importance of having an established security policy. 13:31 - Adding an input rule to iptables 14:55 - Flushing all firewall rules from iptables Reference Materials Guide to Network Defense and Countermeasures - Chapter 9 Additional Information Building a firewall, Part 1 (of 3): http://www.windowsecurity.com/whitepapers/Building_your_firewall_Part_1.html