http://secure45nbquibuw6thmenrfamhobdkkrllgxrtayn4sgmnexremexyd.onion/guides/linux-hardening.html
This guide aims to explain
how to harden Linux as much as possible for security and privacy. This guide attempts to be distribution-agnostic and is not tied to any specific one. DISCLAIMER: Do not attempt to apply anything in this article if you do not know exactly what you are doing. This guide is focused purely on security and privacy,
not performance, usability, or anything else.