The Ultimate Security Check
For a REAL security check, and excellent information on security items, go to the Gibson Research site and click on "Test My Shields." There is now available on that same site, a test of *internal* security to check your machine's capability to block unwanted applications from BROADCASTING from your machine - called Leak Test. And more and better resources are being added all the time.
By the way, I have found one of the best personal firewall systems, as a *free download,* called ZONE ALARM available from the zonelabs.com site. Check it out. I recommend it highly. And I'm sure there are other security programs of good reputation if you just take the time to look for them. They can all be tested with the tools on the Gibson site or other Security Check sites.
A great site regarding Security, Testing, and Tools is Privacy.Net . Check here for information and lots of links.
DSL Reports has a very good "Security Check" site. Another Security Check site is provided by it.sec .
Information on firewalls and security for Macintosh users is available here
Another site with multiple security checks is at Fierwall Leak Test