RedHat Enterprise Linux 5.3 ships with a default iptables ruleset installed that will reject all incoming traffic. Before you can use some services you must add rules to iptables so the services will work. Below is a list of common rules that users would use.

• These examples assume you are making the firewall changes as a normal user with 'sudo' privileges

HTTP - Port 80

 
# sudo /sbin/iptables -I RH-Firewall-1-INPUT 1 -p tcp --dport http -j ACCEPT

HTTPS/SSL - Port 443

 
# sudo /sbin/iptables -I RH-Firewall-1-INPUT 1 -p tcp --dport https -j ACCEPT

SSH - Port 22

 
# sudo /sbin/iptables -I RH-Firewall-1-INPUT 1 -p tcp --dport ssh -j ACCEPT

FTP - Port 21

 
# sudo /sbin/iptables -I RH-Firewall-1-INPUT 1 -p tcp --dport ftp -j ACCEPT
# sudo /sbin/iptables -I RH-Firewall-1-INPUT 1 -p tcp --dport ftp-data -j ACCEPT

MySQL - Port 3306

 
# sudo /sbin/iptables -I RH-Firewall-1-INPUT 1 -p tcp --dport mysql -j ACCEPT

Save Your Rules

 
# sudo /sbin/service iptables save

--Kelly Koehn 15:48, 16 July 2009 (CDT)