Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

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

Possible Duplicates:
Why should I firewall servers?
Why would I need a firewall if my server is well configured?

For a single web server that only listens on 22/80/443, is a firewall (iptables) really necessary? What exactly is it protecting against if there are only two properly configured services listening on three ports?

share|improve this question

marked as duplicate by jscott, pauska, Khaled, Massimo, MadHatter Jul 18 '11 at 14:03

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Yes. It provides you with a buffer against incoming attacks and (which most people forget) outgoing malicious traffic, like reverse proxies, spam bots, etc., with the appropriate egress filtering, of course.

share|improve this answer
I don't know... is it really necessary? Necessary is one of those words that as a pedant I'd say no. But are you foolish to not run one, given the protection it offers with minimal hassle in maintenance and configuration? In my opinion, yes. – Bart Silverstrim Jul 18 '11 at 14:48

Not the answer you're looking for? Browse other questions tagged or ask your own question.