LinuxQuestions.org - Iptables newbie: Avoiding connections from 130.40.23.12

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Iptables newbie: Avoiding connections from 130.40.23.12

Hi.

I want to implement an Iptables rule to avoid any connection from 130.40.23.12.
Is this correct?

iptables -A INPUT -i eth0 -p TCP -s 130.40.23.12 -j REJECT

Thank you very much.

If by any connection, you mean TCP packets coming in on eth0 whose final destination is your machine, then yes, that is correct.

You could remove the -i eth0 and the -p TCP to reject all packets coming in on all interfaces (i.e. ICMP or UDP on eth0 or eth1):

Code:

iptables -A INPUT -s 130.40.23.12 -j REJECT

Alternatively, if you don't want to send a rejection message back to 130.40.23.12, Simply DROP the packet:

Code:

iptables -A INPUT -s 130.40.23.12 -j DROP

If you want to reject/drop all packets coming from that machine, i.e. those destined for your local machine and those that would route through it to another machine, duplicate one of the above rules, but change INPUT to FORWARD. To block outgoing connections, duplicate again, this time using OUTPUT instead of INPUT.