links
misc:
http://csrc.nist.gov/publications/PubsSPs.html
https://lifehacker.ru/2017/01/09/free-oreilly-ebooks/
http://lukatsky.blogspot.ru/2013/07/security-for-dummies.html
Debian:
https://www.debian.org/doc/manuals/debian-reference/ch05.en.html
https://wiki.debian.org/ru/NetworkConfiguration
netfilter:
https://www.opennet.ru/base/net/iptables_inside.txt.html