open proxy server - Computer Definition
A proxy server that is configured so that anyone can use it. There are public access proxy servers on the Internet that are intentionally open to the general public, and there are countless private proxy servers that are unintentionally left open because they are not configured properly. Open proxy servers are widely used by spammers to send spam because the proxy hides the spammer's IP address from recipients. Spammers routinely scan the Internet for vulnerable proxy servers. See honeyproxy and proxy server.