"If your HTTP proxy uses authentication, then you'll
need to tell it about the username and password to use This is
where the concept of "auth-file" comes into play. All you have to
do is put your username & password, separated by a colon, into
a textfile. Once you've done this, you just have to tell corkscrew
where to find the auth-file. Create a file called .corkscrew-auth
in your home directory"