InstallingSecurityTools - Community Ubuntu Documentation
help.ubuntu.com/community/InstallingSecurityTools
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
The Ubuntu repositories contain several useful tools for maintaining a secure network and network administration. This page attempts to list the most popular and useful of these utilities, a brief description of them, and how to install them.