Chromebooks & "Client is blacklisted due to IP address theft policy"

[eduserverteam]

We are getting a lot of IP address thefts with Chromebooks that has started happening recently

We are using a Cisco Catalyst 9800-80 Wireless Controller with ver 17.6.3

Anyone have any pointers?

Dave

[Haydn Andrews · Accepted solution]

Are you by any chance using flexconnect and the same subnet for the chromebooks at each site with NAT to the internet?

There is a feature called overlapping IP if you are that you need turned on.

[MikeKilo · Accepted solution]

To add to Haydn's comment,

This can be found in Configuration --------- Tags and Profiles ----------- **Flex Profile you created** ---------- Tick IP overlap.

[eduserverteam]

Tried this today at one of our sites, and it does seem to have fixed the problem.  I'm not sure why we were having the problem though.  From what I can tell, IP theft occurs when a device gets an IP address the same as an existing device.  That shouldn't happen in our environment.  We have different scopes for different sites.  We have split the sites down the middle, and each half has it's own DHCP server environment (2 servers, replicated).  There are different scopes on each DHCP server.  So it should not be possible for a device to get a duplicated IP address.

Am I missing something?