List and Delete iptables Firewall Rules in Linux

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Another great tutorial I would like to add that is you want to reduce the number of SSH brute force attacks you can add this CHAIN to your iptables rules. Adjust accordingly to the seconds and hitcount and port for your server.

Create chain for ssh attacks

$ iptables -N SSH_CHECK

$ iptables -I INPUT -p tcp --dport 22 -m state --state NEW -j SSH_CHECK $ iptables -A SSH_CHECK -m recent --set --name SSH $ iptables -A SSH_CHECK -m recent --update --seconds 120 --hitcount 5 --name SSH -j DROP

I locked out myself from ssh ? How do i fix it?

wow… nice, concise, and useful… thank you very much

Great tutorial, it worth to add:

iptables -t nat -X

which will clean chains in nat table too.

Thank you!

I’m having issues deleting a specific rule from my iptables. I used iptables -t nat -S to list the rule: -A POSTROUTING -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to-source 192.168.111.111

and tried to delete it with: $ sudo iptables -D POSTROUTING -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to-source 192.168.111.111 iptables: Bad rule (does a matching rule exist in that chain?).

I’m sure it’s just a syntax issue but I’m having trouble finding a reference that clears it up for me. Any help would be greatly appreciated.