They also have a very useful guide focused on network infrastructure hardening. It's intended for Cisco IOS switches, but many of the principles can be adopted

They also have a very useful guide focused on network infrastructure hardening. It's intended for Cisco IOS switches, but many of the principles can be adopted to other platforms: http://www.nsa.gov/ia/_files/switches/switch-guide-version1_01.pdf http://www.nsa.gov/ia/_files/switches/switch-guide-version1_...