IP-address duplicates on WAN side

[Macormick]

If I accidentally set an IP address used by another device on the WAN interface, how will pfSense complain about this, what should I keep track of to find out about IP address duplicates on the WAN side, somethin to look at in the logs?

We have a big external subnet and sometimes it is difficult to see if any other device has taken an IP.

[viragomann]

@macormick
To see something in the pfSense log requires that pfSense is communicating with that IP. Otherwise there won't be any notice naturally.
In this case you will find ARP entries in the system log saying that the respective IP address has moved from one MAC to another one. And then another entry saying it moved back to the former MAC again.

[stephenw10]

You will see entries in the system log like:

kernel 		arp: aa:bb:cc:dd:ee:ff is using my IP address 100.0.0.101 on ix0! 

If the conflict is with an IP pfSense holds.

Steve