The use of the AUTHINFO is optional. This command as documented
    has a number of security implications. In the original and simple
    forms, all passwords are passed in plaintext and could be
    discovered by various forms of network or system surveillance.
    The AUTHINFO GENERIC command has the potential for the same
    problems if a mechanism is used that also passes cleartext
    passwords. RFC 1731[8] discusses these issues in greater detail.