IPTABLES Configuration

In addition to using system-config-firewall (which is not installed on RHEL by default) one can edit the configuration file directly.  This also helps if you need to add more specific rules.

File: /etc/sysconfig/iptables

Open a port up to everybody:

-A INPUT -m state --state NEW -m tcp -p tcp --dport [Port Number] -j ACCEPT

Open a port up to specific ip address:

-A INPUT -s [IP ADDRESS or Range] -m state --state NEW -p tcp --dport [Port Number] -j ACCEPT

After editing the file just restart iptables using:

service iptables restart