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How can I block all ports except

  1. ssh (port 22)
  2. httpd (port 80)

using iptables and iphains?

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While ochach's answer is technically correct, I think you need to clarify your question. Do you mean "block all input except ssh and http"? If you follow ochach's answer, you won't be able to do anything - no data will be allowed out of your box. – baumgart Jun 15 '10 at 15:37
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migrated from stackoverflow.com Jun 15 '10 at 15:17

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2 Answers

up vote 4 down vote

Ipchains are old and i do not reccomend it

simple script 

#!/bin/bash
IPTABLES=/sbin/iptables

#start and flush
$IPTABLES -F
$IPTABLES -t nat -F
$IPTABLES -X
$IPTABLES -P FORWARD DROP
$IPTABLES -P INPUT   DROP
$IPTABLES -P OUTPUT  ACCEPT

#SSH traffic
$IPTABLES -A INPUT -p tcp --dport 22 -j ACCEPT
#HTTP traffic
$IPTABLES -A INPUT -p tcp --dport 80 -j ACCEPT

#loopback
iptables -A INPUT -i lo -p all -j ACCEPT
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I ran this script on my server and locked myself out :) – Zilupe Apr 23 at 22:45
@Zilupe to easily not loose acces to server remember to use cron while editing firewall - like: */2 * * * * iptables -P INPUT ACCEPT – ochach 3 hours ago
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up vote 0 down vote

Which Linux distribution? You may be better off using a higher level firewall like ufw

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