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Contents
What is a firewall?
TCP/IP Concepts Underlying a Packet-Filtering Firewall
Packet-Filtering Concepts
What can a static firewall protect against?
Notes:
I'm going to talk a little bit about what firewalls are, what they do, and what they protect us against. In terms of firewalls, I'll focus on Linux ipchains packet-filtering firewalls.
Throughout all of this, it's important to remember that security requires a hierarchical approach, security in depth. A firewall is not a panacea, and it's not any one thing. There is no single magic bullet.
A static firewall can do nothing for a poorly administered system that’s connected to the Internet.