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?


1 Answer 1


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.

  • 2
    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. Jul 18, 2011 at 14:48

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