--- orig/interfaces.template	2014-08-11 15:25:07.380165080 +0200
+++ patched/interfaces.template	2014-08-11 15:26:06.899773745 +0200
@@ -7,8 +7,9 @@
 auto lo
 iface lo inet loopback
 
-{% for ifc in interfaces -%}
+{% for ifc in interfaces %}
 auto {{ ifc.name }}
+{%- if ifc.address %}
 iface {{ ifc.name }} inet static
         address {{ ifc.address }}
         netmask {{ ifc.netmask }}
@@ -19,8 +20,9 @@
 {%- if ifc.dns %}
         dns-nameservers {{ ifc.dns }}
 {%- endif %}
-
+{%- endif %}
 {% if use_ipv6 -%}
+{%- if ifc.address_v6 -%}
 iface {{ ifc.name }} inet6 static
     address {{ ifc.address_v6 }}
     netmask {{ ifc.netmask_v6 }}
@@ -28,5 +30,5 @@
     gateway {{ ifc.gateway_v6 }}
 {%- endif %}
 {%- endif %}
-
-{%- endfor %}
+{%- endif %}
+{% endfor %}