persist port routing from 80 to 8080

Question

I use amazon EC2 instance which works via ubuntu. By default according security restrictions I can't bin my application to port 80, so I just bind it port 8080 and then set routing redirect from port 80 to 8080 via the following command:

iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to 8080

But I found that when I reboot the server this settings no longer active untill I invoke this command again.

So my question is how to enable port's redirect work even if system was rebooted?

Solution 1

You can add this command in /etc/rc.local , so it will be executed automatically after reboot .

Solution 2

Use the iptables-save command instead.

Firewall rules should never go into rc.local script. rc.local is the last thing to be executed. If a block rule has been placed into rc.local there is a small time frame where an attacker can exploit a rule not being in place.

While it probably doesn't matter with this situation, it is still best to not get into a bad habit that may bite you later.

Solution 3

Here is how the official iptables' documentation teaches us. See here

Add these two lines in /etc/network/interfaces:

pre-up iptables-restore < /etc/iptables.rules
post-down iptables-save > /etc/iptables.rules

The line post-down iptables-save > /etc/iptables.rules will save the rules to be used on the next boot.

Comments

[Ph0en1x]

Already did that, but still thanks for the answer

[nux]

welcome my friend , thats a good trick

[Dirk Groeneveld]

This works, but the real answer is @MeOMy's answer below.

[birgersp]

ran "sudo iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to 8080" and "sudo iptables-save". But routing was reset on reboot. Did I misunderstand how to do this?

[Thomas Ward]

The answer is incomplete. iptables-save > some-file-path saves the rules, and then you would restore them via iptables-restore < some-file-path in rc.local. Or install iptables-persistent which does this during boot as a service.

[DeeJayh]

Kudos for using the officially recommended method and, in this case, simplest method, to complete this task. I'd +2 if I could for using the KISS method.

[birgersp]

I'd like to understand how to do this. Be more specific, please