Re: can I used netlink to monitor changes to ARP table and to dump

kuznet@ms2.inr.ac.ru
Fri, 17 Dec 1999 16:43:26 +0300 (MSK)


Hello!

> I have been using netlink to dump and monitor for changes to the
> forwarding/routing table and links. Can netlink be used to monitor changes
> and dump the ARP table?

Yes. Dumping is made exactly in the same way as you do it for routing tables.
F.e. look into iproute source: "ip neigh ls" command does it.

Monitoring changes is more tricky. ARP used to create pretty
high traffic on netlink, so that reporting is not turned on by default.
To enable it it is necessary to make two things:

1. CONFIG_ARPD
2. echo 1 > /proc/sys/net/ipv4/neigh/<dev>/app_solicit

After this arp changes are reported to group RTMGRP_NEIGH.

Yes, it is inconvenient, because requests are dumped too.
But without some optimizations in netlink, which I permananltly forget
to make, unconditional reporting is really harmful.

Alexey
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