Budget Firewall

Exposing Yourself

There are certain types of malicious attacks that most types of firewalls cannot prevent against, such as certain types of DOS (Denial of Service) attacks, certain types of DDOS (Distributed Denial of Service) attacks, a ping flood, or other high-traffic flood. The firewalls mentioned do not have any way of checking the Layer 5-7 traffic to determine if the traffic should be blocked; therefore, any service that is open (e.g. SMTP, POP3, and HTTP) and has an exploit is vulnerable. It is important to keep up-to-date on server software patches and to keep an eye on the various security mailing lists and announcements.

The best firewalls also cannot protect against weak passwords, back doors left open, un-patched Web servers, or other common sense type security measures. A firewall is only one piece in a larger security picture, and, as the saying goes, security is only as strong as its weakest link.

These open-source, server-based firewall solutions offer a great alternative to the commercial firewall products. They are effective, flexible, and free. Although they might not provide all the functionality of commercial firewalls, they do provide protection in situations where commercial firewalls are not a viable choice.

Tony Bourke wrote this article for HostingTech, a web hosting magazine, and can be contacted at tbourke@hostingtech.com