Here's some additional reading, courtesy of the Systems and Network Attack Center (SNAC) of the US National Security Agency. Don't worry, it's unclassified.
"The Cisco IOS Switch Security Configuration Guide provides technical guidance intended to help network administrators and security officers improve the security of their networks. It contains principles and guidance for secure configuration of IP switches, with detailed instructions for Cisco IOS switches. The information presented can be used to control access, help resist attacks, shield other network components, and help protect the integrity and confidentiality of network traffic."
Cisco IOS Switch Security Configuration Guide (PDF, 86 pages, 647KB, updated 21 June 2004)
http://www.nsa.gov/snac/os/switch-guide-version1_01.pdf
"The Router Security Configuration Guide provides technical guidance intended to help network administrators and security officers improve the security of their networks. It contains principles and guidance for secure configuration of IP routers, with detailed instructions for Cisco System routers. The information presented can be used to control access, help resist attacks, shield other network components, and help protect the integrity and confidentiality of network traffic."
Router Security Configuration Guide, Executive Summary (PDF, 2 pages, 34KB, updated 10 February 2003)
http://www.nsa.gov/snac/routers/cisco_exec_sum.pdf
Router Security Configuration Guide (PDF, 295 pages, 2297KB, updated 08 April 2004)
http://www.nsa.gov/snac/routers/cisco_scg-1.1b.pdf
That's just the Cisco stuff. To see what else they have for operating systems, applications software etc., go here:
Current Security Configuration Guides
http://www.nsa.gov/snac/downloads_all.cfm
"NSA has developed and distributed configuration guidance for a wide variety of software from open source to proprietary software. The objective of the configuration guidance program is to provide NSA's customers with the best possible security options in the most widely used products."
