At well over 900 pages, one would expect this book to provide pretty full coverage of security issues in the Unix and Internet environments, and it does.
Security is certainly a moving target, with new security holes and exploits found on a weekly basis.
However, as the field of security administration has grown, methods of configuring and checking hosts and networks have been developed. It is possible to maintain a nearly airtight Unix system, however the complexity of managing a system with many users, or one that is providing many services on the network, often leads to holds in security being opened unintentionally. And even simple home systems with dynamic IP addresses are at risk. The only way to avoid these weaknesses is to maintain a continual and disciplined vigilance over the network and system, along with full awareness of the state of security provided by the current configuration and how it is impacted by administrative manipulation. The authors of this book seem to have stuffed every possible detail on security into their book.