{
    return "" unless (defined $ExternalInterface && defined $GatewayIP);

   my $OVH =	 $ExternalInterface{'OVH'} || 'no';
    return "" unless ($OVH eq 'non'); 

    my $dev = ($ExternalInterface{Configuration} eq 'disabled') ?
	$InternalInterface{Name} :
	$ExternalInterface{Name};
    return "GATEWAYDEV=$dev";
}