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I'm new at iptables. I'm trying to whitelist a IP. My server is behind a proxy and I'm getting refused connections since the server is thinking the proxy Ip is attacking it.

I have tried this below

/sbin/iptables -I INPUT -1 eth0 -s 111.11.1111.111 -j ACCEPT

The IP above is example only.

The OS is Ubuntu 11.10

I was wondering if that's the correct way to add it. I also don't know how to save it. I guess every time you reboot you have to add it. I was wondering what the command was to save it so I don't have to keep adding it.

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After rebooting, what is the output of iptables -n -L? Are the lists empty? If so, then you shouldn't need to add a rule to accept. If the list is not empty, then you already have something managing your firewall, figure out what it is. – Zoredache Feb 21 '12 at 23:54

Your iptables command is nearly correct, with a few exceptions:

  • The -I option means Insert, which requires an additional argument to specify where in the rule list the new rule should appear. For example -I INPUT 1
  • I believe you wanted -i instead of -1 to specify and input interface specification.
  • (optional) You've allowed all traffic, on any port, from this proxy system. You probably want to specify a protocol and/or port. Such as -p tcp --dport 80, which means protocol TCP with a destination port (on the local system) of 80. This would allow HTTP traffic.

That all aside, Ubuntu uses a configuration tool called UFW (Uncomplicated Firewall). You'll probably want to take a look at some documentation for how you can add custom iptables rules. Although, you can use UFW directly to add a simple destination rule like this, with:

sudo ufw allow from to any app apache

This assumes you're trying to allow access to apache. For other applications, you could try:

sudo ufw app list
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