How does NAT reflection (NAT loopback) work?
I use the auto generated rules that come from OpenWRT as an example of NAT reflection (NAT loopback).
iptables
Iptables: matching outgoing traffic with conntrack and owner. Works with strange drops
In my iptables script I have been experimenting with writing as finely grained rules as possible. I limit which users are allowed to use which services, partly for security and partly as a learning exercise.