This isn't really a "problem" as such, just a nuisance.  For
some time now, I have had a computer running NetBSD, acting as a
firewall/NAT.  I recently began receiving messages such as:

Mar  9 15:18:53 ffpl-gw /netbsd: 10:00:5a:ba:bb:66 on ne1 tried
to overwrite arp info for 192.168.0.1 on lo0
Mar  9 15:21:08 ffpl-gw last message repeated 5 times
Mar  9 15:38:53 ffpl-gw last message repeated 12 times

"ne1" is the NIC that connects to our upstream provider.  I
assume that there is a computer over there (a switch or router
maybe) that is broadcasting ARP entries.  Here is my ifconfig:

ne0:
flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST>
mtu 1500
        address: 00:c0:f0:44:4a:11
        media: Ethernet autoselect (10baseT full-duplex)
        inet 192.168.0.1 netmask 0xffff0000 broadcast
192.168.255.255
        atalk 65280.49 range 1-65534 phase 2 broadcast 65280.49
ne1:
flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST>
mtu 1500
        address: 00:c0:f0:34:ad:bd
        media: Ethernet autoselect (10baseT full-duplex)
        inet 204.112.243.26 netmask 0xffffff00 broadcast
204.112.243.255
lo0: flags=8009<UP,LOOPBACK,MULTICAST> mtu 32976
        inet 127.0.0.1 netmask 0xff000000
        atalk 0.0 range 0-0 phase 2

Is there any way to stop these messages without changing my
entire internal network over to a different private IP block?  I
have all of the private network IP addresses blocked on ne1, but
that doesn't help any.

Thank you for your time,

-- 
Tyler Mitchell