FreeNAS complains that something is taking its IP

[tofagerl]

So this just happened, and took me 40 minutes to diagnose since the logs were out of reach due to idiocy on my part:
arp: e8:37:XXX::16 is using my IP address 10.0.0.138 on bridge0!

Here's what's interesting: My FreeNAS uses 10.0.0.37. Its jails all use different addresses. And the router which DOES use 10.0.0.138, and always has and always will, has :1A as the last number, not 16 - though the rest matches. It's possible that 16 is the MAC address of one of its LAN ports, but I don't know how to check that.

So here's what this led to: Nothing being able to reach the Internet unless the FreeNAS was disconnected. (That part took half an hour). My logs where being sent to papertrail, and I couldn't access papertrail until I knew that...
This is what fixed it: Rebooting both the FreeNAS and the router at the exact same time. (That part took ten minutes).

I would very much like for this never to happen again. Any tips?

I was in fact configuring a jail before this happened, which is the only thing that could have caused it, but that jail has 10.0.0.140 (no dhcp) and a completely different MAC.

 

[m0nkey_]

If you're seeing that message, then you have an IP conflict. You had a jail which came up on the same IP address as your router.

 

[tofagerl]

No. I checked that in the last part, and they were all set to different adresses.
Although I'm almost certain it was a configuration error on my part, don't get me wrong. Just not that specific one.

 

[depasseg]

And the router which DOES use 10.0.0.138, and always has and always will, has :1A as the last number, not 16 - though the rest matches

Is your router NIC the same HW mfr as your FreeNAS NIC? It's odd that they would match except the last number.
In the future, you can use arp -a to see the HW ARP table, and do some troubleshooting. It sounds like an interface was misconfigured though.

 

[tofagerl]

I doubt it. The Router is a Zyxel from my ISP, and the NIC is on a Gigabyte mobo, so it's probably either a Realtek or an Intel.

 

[depasseg]

So then there was probably something a little mixed up in FreeNAS because the HW addresses that close would be the same silicon provider.