I notice that the ARP table does not only contain entries that are the result of an ARP reply to an outgoing ARP request by the router (router needs to talk to IP a.b.c.d, sends out “ARP who is a.b.c.d” and gets the MAC address in the reply), but it also caches ARP entries as a result of hearing ARP requests from others.
(other systems ask “ARP who is w.x.y.z” on the network, but w.x.y.z is not the address of the router)
Is there some configuration option to turn off this behaviour? It clutters the ARP table with many addresses that the router never needs to communicate to. I’d prefer if the router only stores ARP information it has requested itself.