I just remembered I had to write a small script for Nmap’s Scripting Engine to test for an Open Proxy. This is the first version, which I had JUST posted to the nmap-dev mailing list.
Test it out and let me know how it works, or whatever. Flames to YOUR /dev/null, please. 😛
Download it from HERE.
UPDATED: 20060927. Added explode() function. Header-only matching now works.
UPDATED: 20070413. API Fixes, general fixes. Does not return string when non open.