SOCKS5 is the most recent version of the SOCKS protocol. It solves both the problems of
SOCKS4 mentioned above. Security is enhanced through the use of an extensible
authentication system. The standard includes three authentication methods:
Null authentication – requiring no authentication.
Username/password authentication – where the client must provide a user-name and a password to
be allowed to access the proxy server.
GSS-API authentication – where the client and server use operating system-level authentication
methods to verify identity. Not yet implemented.