Duplicate iptable rules

Solution 1:

List with line numbers and delete by number.

iptables --line-numbers --list

Then delete one rule using it's line number. Then repeat (line numbers change for following rules when one is deleted so re-list before deleting another).

iptables -D INPUT 6

Solution 2:

iptables-save | uniq | iptables-restore

That is all you need really.

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Solution 3:

If you only want to delete double lines that are directly one after another you can export, unify and reimport it with

mkdir ~/tmp
iptables-save > ~/tmp/iptables.conf
uniq /tmp/iptables.conf > ~/tmp/iptables_new.conf
iptables-restore < ~/tmp/iptables_new.conf

If you want to delete other lines use an editor on ~/tmp/iptables.conf before you reimport it the same way.

Check your new rules with

iptables-save

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Solution 4:

A comment to fail2ban: fail2ban seems to add its iptables rules itself. So you should not store these rules with e.g. iptables-save. Then after a reboot the rules will be doubled (your saved rule + the rule added by fail2ban).

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Solution 5:

Delete all duplicated lines except COMMIT

/sbin/iptables-save | awk '!COMMIT||!x[$0]++' | /sbin/iptables-restore