Notes

Outline

Chapter 7 Firewalls

Firewall Definition A network device that enforces network access control based upon a defined security policy

Basic Firewall Philosophy

Types of Firewalls Circuit-level firewall verifies TCP 3-way handshake on behalf of inside hosts Proxy server firewalls application aware Proxies TCP connections on behalf of clients not transparent to end-users Non-stateful packet filters Stateful packet filters Maintains source/destination TCP/UDP port numbers, TCP sequence numbers, TCP flags, TCP session state, and UDP traffic timing based on timers Application aware Personal firewalls