Proxyjudge
A Proxyjudge is a script use to test HTTP proxies for anonymity. There are two common scripts, one called simply "ProxyJudge", and the other is called "AZ Environment Variables". The first type outputs an anonymity rating(1-5, 1 being the best, 5 being the worst), and the second type just displays all variables sent by the proxy to the web page.
The variables can include:
DOCUMENT URI - The location of the script
ERRLOGFILE - where the log file for the judge is stored
GATEWAY_INTERFACE - the gateway interface
HTTP ACCEPT - which protocols The Browser will accept
HTTP ACCEPT CHARSET - the browsers charset
HTTP ACCEPT LANGUAGE - the browsers language
HTTP_CONNECTION - type of connection, usually keep-alive
HTTP_COOKIE - cookie accepted
HTTP_HOST - site hosting the judge
HTTP_KEEP_ALIVE - in milliseconds
HTTP REFERER - where the browser was directed from
HTTP_USER_AGENT - details about the name and type of browser
PATH - path
QUERY_STRING - if a search engine was used
REMOTE_ADDR - your ip address (or the proxy if you are using one)
REMOTE_PORT - port used to connect
REQUEST_METHOD - get or put
SCRIPT_URI - the full http:// url to the script
SCRIPT_URL - the script url relative to root
TMPDIR - location of the temp dir on the server
TZ - your timezone