# 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:

```
kernel: in_arp: ff:ff:ff:ff:ff:ff is multicast
```
What is it?

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


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## 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?


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## kirush (Apr 2, 2013)

It's PC2.


```
----[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


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