Book excerpts:

This book describes a set of guidelines for writing secure programs on Linux and Unix systems. For purposes of this book, a 'secure program' is a program that sits on a security boundary, taking input from a source that does not have the same access rights as the program. Such programs include application programs used as viewers of remote data, web applications (including CGI scripts), network servers, and setuid/setgid programs.

The modification of the operating system kernel itself is not addressed, although many of the principles discussed here do apply. These guidelines were developed as a survey of 'lessons learned' from various sources on how to create such programs (along with additional observations by the author), reorganized into a set of larger principles. This book includes specific guidance for a number of languages, including C, C++, Java, Perl, PHP, Python, Tcl, and Ada95.

This book does not cover assurance measures, software engineering processes, and quality assurance approaches, which are important but widely discussed elsewhere. Such measures include testing, peer review, configuration management, and formal methods. Nor this book discusses how to configure a system (or network) to be secure in a given environment. This is clearly necessary for secure use of a given program, but a great many other documents discuss secure configurations.

Finally, this book assumes that the reader understands computer security issues in general, the general security model of Unix-like systems, networking (in particular TCP/IP based networks), and the C programming language. This book does include some information about the Linux and Unix programming model for security.