Block ip address of spammers with iptables under Linux

Q. How do I block ip address of spammers with iptables based firewall under CentOS Linux 5?

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A. You can simply block IP address of spammers by editing /etc/sysconfig/iptables file under:

a) CentOS Linux
b) Fedora Linux
c) RHEL 4.x/5.x etc

Open file /etc/sysconfig/iptables:
# vi /etc/sysconfig/iptables
Append ip address of spammers as follows:
-A RH-Firewall-1-INPUT -s SPAMMER-IP -j DROP
-A RH-Firewall-1-INPUT -s SPAMMER-SUBNET-BLOCK -j DROP

Save and close the file. Just restart the firewall:
# /etc/init.d/iptables restart

You can also create a small shell script to block lots of IP address at a time.

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4 comments… add one
  • Andy Sep 25, 2007 @ 19:20

    Hi

    Do you know of any way that it does it automatically by getting a list of known spammers from the internet?

  • kunal Oct 15, 2007 @ 6:16

    How to automatically block a user after multiple failed sshd logins say after 3 failed logins
    for temporary time say 2 days.

  • ccpizza Aug 30, 2009 @ 12:13

    2kunal:
    check out denyhosts (http://denyhosts.sourceforge.net)

  • dbw Oct 3, 2009 @ 12:21

    Check out project honey pot. They have a list of spammers, and you can also help find spamming ips by joining their project.

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