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Let us continue with the example from the previous subsection.

netadm@alisa:~ # ip maddr add 33:33:00:00:00:01 dev dummy
netadm@alisa:~ # ip -0 maddr ls dummy
2:  dummy
    link  33:33:00:00:00:01 users 2 static
    link  01:00:5e:00:00:01
netadm@alisa:~ # ip maddr del 33:33:00:00:00:01 dev dummy

1cm NB. Neither ip nor the kernel check for multicast address validity. Particularly, this means that you can try to load a unicast address instead of a multicast address. Most drivers will ignore such addresses, but several (f.e. Tulip) will intern it to their on-board filter. The effects may be strange. Namely, the addresses become additional local link addresses and, if you loaded the address of another host to the router, wait for duplicated packets on the wire. It is not a bug, but rather a hole in the API and intra-kernel interfaces. This feature is really more useful for traffic monitoring, but using it with Linux-2.2 you have to be sure that the host is not a router and, especially, that it is not a transparent proxy or masquerading agent.