This part of the book discusses issues that arise when organizational networks are interconnected with the Internet. It also discusses ways of increasing your security through better programming.

• Chapter 21, Firewalls , describes how to set up various types of "firewalls" to protect an internal network from an external attacker.

• Chapter 22, Wrappers and Proxies , describes a few common wrapper and proxying programs that help protect your machine and the programs within it without requiring access to source code.

• Chapter 23, Writing Secure SUID and Network Programs , describes common pitfalls when writing your own software. It gives tips on how to write robust software that will resist attack from malicious users.