Protect Your Server with APF Firewall
There are many firewall solutions out there, and I do not pretend to be an expert on security. Nevertheless, I can testify from experience that some solutions are easier, more secure, and more affordable than others. APF(Advanced Policy Firewall) from R-fx Networks is one solution that has worked for me. It is free and easy to use.
By default, Linux distributions come with a program called iptables, which manages the Linux kernel firewall. It is a powerful program that handles most network security issues for the server, but it is very easy to use when you get into more intricate customization.
APF is based on iptables and manages the firewall tables, rather than replacing them. This means that you can keep your current configuration and just install APF to manage your firewall settings.
APF provides the following filtering system:
1) Static rule based policies (not to be confused with a “static firewall”)
2) Connection based stateful policies
3) Sanity based policies
With it you can manage inbound and outbound network traffic, easily configuring the ports you want to permit or deny, the protocols you want to allow, and the filters you want into place. I used this simple yet powerful firewall system on my dedicated server for years, and I never had firewall-related security problems.
APF is free to download and can be install in minutes. It runs as a system service (daemon) that you can start, stop, or restart as needed. It is free and open source software, released under the GNU General Public License.