Thanks for your patches, Darsha. I didn't apply them as they are but decided to 
slightly adjust them:

* iptables shouldn't be a dependency but just a Recommends (it's not a strict 
dependency for all the scripts of grml-network)

* [ "$(id -ru)" -ne "0" ] isn't a string match, it would have to be != - but in 
agreement with Frank (our shell specialist) we decided to use "[ $(id -ru) -ne 
0 ]" instead

Fixed in git - upload will happen soon, thanks for your feedback and patches!

regards,
-mika-