Thu Aug 18, 2022 4:34 pm
The way I understand it, is that its a way to (within a set of mangle rules) tell the router to not remove the packet from the chain but to keep processing it through the next rule in the chain even though you may have matched a condition.
In other words instead of a rule matching and being accepted the packet does NOT exit the chain but continues to the next rules in the chain........... and so forth.
If you want the packet not to continue in the chain then use passthrough=no, the next time the packet is matched (on a subsequent rule) it exits the chain.
Thus a packet may match on the first rule in a mangle chain but you put in passthrough=yes, because rule 10 in the chain needs also to look at that packet. etc...
and on rule 10 you put passthrough=no because there is no need for the packet to be processes through rules 11-20 (20 being the last rule in the chain).