--- orig/etc/ferm/ferm.conf
+++ mod/etc/ferm/ferm.conf
@@ -8,6 +8,7 @@
 
 def $local_net_ip = $elho_net_ip;
 def $local_net_ip6 = $elho_net_ip6;
+def $local_net_if = ();
 
 def $forward_interfaces = ();
 def $monitor_interfaces = ();
