Snort

Snort is an open source network intrusion prevention and detection system (IDS/IPS) developed by Sourcefire. Combining the benefits of signature, protocol and anomaly-based inspection, Snort is the most widely deployed IDS/IPS technology worldwide. With millions of downloads and approximately 300,000 registered users, Snort has become the de facto standard for IPS.
checkout the link below..
Official site

NESSUS vulnerability assessment tool

The Nessus vulnerability scanner is the world-leader in active scanners, featuring high-speed discovery, configuration auditing, asset profiling, sensitive data discovery and vulnerability analysis of your security posture. Nessus scanners can be distributed throughout an entire enterprise, inside DMZs and across physically separate networks.

How do I search for a Yahoo! member?

It's easy to find a Yahoo! member. Go to the Yahoo! Member Directory(http://ca.members.yahoo.com) and find the area marked "Find People on Yahoo!" at the top of the page.

You can search by Yahoo! ID, real name, or keywords. Enter your search term into the box and check the appropriate option below. When you are done making your selections, then click the "Find" button to bring up the results.

The Yahoo! Member Directory search can only display up to 500 results for each query. If you would like to see additonal profiles you may need to increase your search criteria or try using the advanced search.

Note: Some public profiles will not show up in a Member Directory search, depending on weather or not the owner of that profile has chosen to make that profile publically searchable.