sub get_proxy_credentials {
    my $self = shift;
    my ($user, $password);
    if ( defined $CPAN::Config->{proxy_user} &&
         defined $CPAN::Config->{proxy_pass}) {
        $user = $CPAN::Config->{proxy_user};
        $password = $CPAN::Config->{proxy_pass};
        return ($user, $password);
    }
    my $username_prompt = "\nProxy authentication needed!
 (Note: to permanently configure username and password run
   o conf proxy_user your_username
   o conf proxy_pass your_password
     )\nUsername:";
    ($user, $password) =
        _get_username_and_password_from_user($username_prompt);
    return ($user,$password);
}