Linux Firewall – How to Test Iptables Rules to Prevent Remote Lockout

iptableslinux

As I'm learning about iptables I've made a couple of mistakes and locked myself out.

What method(s) do you use to test rules without locking yourself out?

I'm using ubuntu server 12.04 LTS

All the answers below were helpful. In the end I used a combination of options. It also helps to have IPMI access to your remote server just in case! But ideally test the rules locally on a replicated environment and test that first. Vagrant helps in this regard to get test setups working quickly.

Best Answer

iptables-apply is specifically designed for this. It applies your rules, and then prompts you to affirm. If you don't affirm, it rolls them back out. So if you brick the system or lock yourself out with apply, it rolls back.

Related Solutions

Linux – How to cleanly and silently reload iptables rules

Have you tried loading your new rules with the iptables-restore command? This is in theory an atomic operation, which may take care of most of your issues. This does require that you write your rules in the format used by iptables-save.

Linux – How to make iptables rules expire

If you mean for iptables to completely remove the rule by itself you won't be able to do it, as far as I know. What's the purpose of this? If you need some kind of automatic temporary banning the standard solution is fail2ban.

Alternatively you can use a cron job to remove the rule you're adding, or, better if you want to do it interactively, an at job:

iptables -I INPUT -s 192.168.1.100 -j DROP
echo "iptables -D INPUT -s 192.168.1.100 -j DROP" | at @10pm

Also take a look at the recent module of iptables. This with its --seconds option may be of help, depending on your actual needs. man iptables for more information.

Best Answer

Related Solutions

Linux – How to cleanly and silently reload iptables rules

Linux – How to make iptables rules expire

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