We can use L7-filter with any iptables option; after all, L7-filter provides just another match option. However, not all the things we can do with our new match option are recommended, because L7-filter might match packets belonging to other applications than the one you want.
Filtering Application Data
Blocking application data that passes through your router is one of the non-recommended things that you can do with L7-filter.
Traffic from different applications might look similar; so you might experience problems when dropping data based on the L7-filter match. For example, if you drop packets that belong to eDonkey, there might be some other protocols that will experience problems. The eDonkey pattern matches about 1% ...