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
Chapter 11, provides background on how TCP/IP
networking programs work and describes the security problems they
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)
Chapter 15, describes both Sun
Microsystems' Network Filesystem (NFS) and the
Windows-compatible Server Message Block (SMB)—in particuar, the
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