gretap interface can now be configured

roles/supernode-interfaces/templates/interfaces.j2

@@ -74,10 +74,11 @@ iface bat0 inet6 static
 {% endif %}
 auto {{backbone.name}}
 iface {{backbone.name}} inet manual
-    pre-up ip link add $IFACE type gretap local {{supernode_local_ip}} remote {{backbone.remote_ip}} dev eth0
+    pre-up ip link add $IFACE type gretap local {{backbone.local_ip}} remote {{backbone.remote_ip}} dev {{backbone.interface|default(supernode_public_interface)}}
     pre-up ip link set up dev $IFACE
     up batctl if add $IFACE
     post-down ip link set down dev $IFACE
+    post-down ip link del dev $IFACE
 {% endfor %}
 {% endif %}