FreeBSD 9.1: kernel: in_arp: ff:ff:ff:ff:ff:ff is multicast

kirush · Mar 28, 2013

Hello!
In /var/log/messages I see:

Code:

kernel: in_arp: ff:ff:ff:ff:ff:ff is multicast

What is it?

Code:

# uname -a
FreeBSD router 9.1-RELEASE FreeBSD 9.1-RELEASE #0 amd64

johnblue · Apr 1, 2013

You are getting those messages in part because of RFC 1812 which states:

A router MUST not believe any ARP reply that claims that the Link Layer address of another host or router is a broadcast or multicast address.

Can you tell us more about the configuration of your FreeBSD box and what it is doing?

kirush · Apr 2, 2013

It's PC2.

Code:

----[internet]--PC1 -192.168.0.254]-----[192.168.0.252 -PC2- 0.1.255.254] ----[ 10.1.0.0/16 clients]

PC2: IPFW, shape, Netflow, mpd5
PC1: NAT