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