fw - fwmark traffic control filter tc " " filter " ... " fw " [ " classid CLASSID " ] [ " action ACTION_SPEC " ]" the fw filter allows to classify packets based on a previously set fwmark " by " iptables . If it is identical to the filter's handle , the filter matches. iptables allows to mark single packets with the MARK target, or whole connections using CONNMARK . The benefit of using this filter instead of doing the heavy-lifting with tc itself is that on one hand it might be convenient to keep packet filtering and classification in one place, possibly having to match a packet just once, and on the other users familiar with iptables " but not " tc will have a less hard time adding QoS to their setups.

classid " CLASSID" Push matching packets to the class identified by CLASSID .

action " ACTION_SPEC" Apply an action from the generic actions framework on matching packets.

Take e.g. the following tc filter statement: will match if the packet's fwmark value is 6 . This is a sample iptables statement marking packets coming in on eth0: tc (8), iptables (8), iptables-extensions (8)