Proxy list
SOCKS is a protocol that relays TCP sessions through a firewall host to allow application users transparent access across the firewall. Because the protocol is independent of application protocols, it can be (and has been) used for many different services, such as telnet, FTP, finger, whois, gopher, WWW, etc. Access control can be applied at the beginning of each TCP session; thereafter the server simply relays the data between the client and the application server, incurring minimum processing overhead. Since SOCKS never has to know anything about the application protocol, it should also be easy for it to accommodate applications that use encryption to protect their traffic from nosy snoopers. No information about the client is sent to the server – thus there is no need to test the anonymity level of the SOCKS proxies.
Proxy Anonymity Levels
Proxy lists are often organized by the various proxy protocols the servers use.