In this article I will introduce you to a few of the commercially-supported open-source network security options currently available in the marketplace today. With open-source networking you can enjoy the benefits of lower costs, greater security, flexibility, extensibility and full enterprise support.

Having many more eyes watching the code and a community of developers backing up users, open source security applications provide a wide range of options and made-to-order uses. Here's a list of 10 serious open source security applications, gathered via the word-of-mouth of the CSOs who use them.

Some quarters in the software industry still carry a bias against the credibility of open source security applications. Open source network gateway developer Untangle did not expect to find its request for certified testing of the popular open source virus security product ClamAV shunned. When it was, Untangle decided to do its own test.

Architecture created by the National Security Agency and expanded with help from the open-source community will save the Defense Department and intelligence agencies millions in hardware costs.

The U.S. National Security Agency has released its own version of the open-source computer operating system Linux, which offers enhanced security for users.

Open source is cheaper than proprietary software, right? In the Data Center Decisions 2008 Purchasing Intentions Survey, lower cost was the top reason cited for converting from proprietary to open source software. And lower cost appears to be a primary incentive for Linux adoption that has fueled the rapid growth of open source in general and of Linux in particular.

Two security researchers have demonstrated a new technique to stealthily intercept internet traffic on a scale previously presumed to be unavailable to anyone outside of intelligence agencies like the National Security Agency.

"We had one client who moved from a Novell/Microsoft-based environment to a Debian-based one and they saved something like 80 percent of the cost in the first year - they couldn't have done that moving to Red Hat - not when their licences cost £1000,"Callway said.

About a year ago, we took a look at the growing trend toward open-source security and highlighted 10 of the best apps available. Since then, the area has continued to mature, and now we're back highlighting 75 of the most frequently downloaded open-source security applications.