Review: Nose Around With Snort
The name Snort may conjure images of a specially trained swine sniffing out truffles. But Snort isn't an animal--it's an IDS (intrusion-detection system) with a rich language for matching patterns in network traffic. Snort provides a slimmed down, customized signature set to detect defined policy violations. It can determine, for instance, whether specific protocols are in violation of a security policy.
Let's face it, unless you're actively policing security-policy compliance, just having words in a document won't make you secure--you have to find policy violations and enforce your policies. Some of the products that prevent policy violations are pricey, but free and open-source Snort may be the only tool you need.