This part of the book is about the ways in which individual Unix computers communicate with one another and the outside world, and the ways in which these systems can be subverted by attackers who are trying to break into your computer system. Because many attacks come from the outside, this part of the book is vital reading for anyone whose computer has outside connections.
Chapter 10, describes how modems work and provides step-by-step instructions for testing your computer's modems to see if they harbor potential security problems.
Chapter 11, provides background on how TCP/IP networking programs work and describes the security problems they pose.
Chapter 12, the longest chapter in this book, explores the most common TCP and UDP services and explores how you can secure them.
Chapter 13, one of the shortest chapters in the book, looks at the Remote Procedure Call system developed in the 1980s by Sun Microsystems. This RPC system is the basis of NFS and a number of other network-based services.
Chapter 14, discusses services for authenticating individuals over a network: NIS, NIS+, Kerberos, and LDAP. It continues the discussion of the Pluggable Authentication Module (PAM) system.
Chapter 15, describes both Sun Microsystems' Network Filesystem (NFS) and the Windows-compatible Server Message Block (SMB) ”in particuar, the Samba system.
Chapter 16, describes common pitfalls you might encounter when writing your own software. It gives tips on how to write robust software that will resist attack from malicious users. This information is particularly important when developing network servers.
