TwoFTPD authentication front-end
reads a username and password from the network and authenticates them
using the CVM module
If the authentication succeeds, it sets the environment variables
to the user's UID, GID, home directory, and login name respectively,
and then executes
It also sets
if the CVM reports a group name, and
look for this variable to determine what startup banner code to use).
The maximum number of authentication attempts to allow before dropping
The maximum number of seconds to wait for successful authentication.
If set, the contents of this variable will be sent as extra responses
before the user logs in.
The maximum number of seconds to wait for command input.