Iptables

Z oficialnej stranky:
netfilter.org is home to the software of the packet filtering framework inside the Linux 2.4.x and later kernel series. Software commonly associated with netfilter.org is iptables.

Software inside this framework enables packet filtering, network address [and port] translation (NA[P]T) and other packet mangling. It is the re-designed and heavily improved successor of the previous Linux 2.2.x ipchains and Linux 2.0.x ipfwadm systems.

Nasledujuci diagram znazornuje cestu packetu v ramci linuxoveho stroja:

Tabulka filter

Odkazy:
Seriál Vše o iptables
Seriál Stavíme firewall
https://www.docum.org/docum.org/kptd/
https://www.booleanworld.com/depth-guide-iptables-linux-firewall/