Lecture 12: Firewalls

Puzzle. Microsoft spent February, 2002, teaching its programmers how to check their code for security vulnerabilities and how to spot common security flaws. Yet many Microsoft programs have security vulnerabilities. What problems do you think Microsoft encountered, and will encounter, in trying to find and clean up the vulnerabilities in its systems?

1. Mail relays
   1. Cypherpunk type 1 remailers
   2. Cypherpunk type 2 (mixmaster) remailers
2. Firewalls
   1. Where they go and what they do
   2. Packet-filtering firewalls
   3. Application layer firewalls
   4. Proxies