Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I'm currently trying to debug a particularly hairy set of DNAT based iptables rules (the UDP reply never makes it back to the original requester) and I'm struggling to visualise the packet flow through all the numerous tables involved. So far Google'ing has shown me old 2.4 based ipchains ones. The netfilter site has some good text docs but is short on diagrams and a number of the external links are now dead.

So is there a canonical diagram for iptables packet flow, preferably showing how NAT/Masqueraded packets are also dealt with?

share|improve this question

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.