proxycheck is a simple tool that will work on a reasonable *nix system
and may be used to quickly check whenever a given host or set of hosts
has open proxy server running.

Open proxies of various kinds are (ab)used nowadays for various evil
things like sending mass spam, hacking into your machine, making denial
of service attacks (DoS) and the like. Every such machine should be
either secured properly or turned off permanently, but that's not an
option, since in most cases there is either no administrator of such
machines exists at all, or he has no clue about what's on that machine,
or it's irrelevant for him.

Homepage:
https://www.corpit.ru/mjt/proxycheck.html
