A properly configured firewall can greatly increase the security of RHEL / CentOS based system. How do I configure a shorewall based firewall for CentOS or Red Hat Enterprise Linux system with an Internet connection? How do I install and configure shorewall to protect the following small business network? The Shoreline Firewall (also known as “Shorewall”), is a Netfilter (iptables) based firewall that can be used on a dedicated firewall system, a multi-function gateway/ router/server or on a standalone GNU/Linux system.