Assign IP Range to specific AP

Simon Hobson dhcp1 at
Mon Apr 25 15:09:41 UTC 2016

Ashley M. Kirchner <kirash4 at> wrote:

> Our network has three different access points (AP), all of them connected to the same subnet. Two of them are being used for the employees in the building, and the third one is a guest AP. DHCPd is currently configured so that all the pools are denying unknown-clients. For the public AP, I have to create a (public) pool that does allow unknown-clients, but how would I restrict that pool to only assign IPs to devices connecting through that one AP? Right now if any unknown client connects through the other APs or directly through the network, that (public) pool assigns an IP. I don't want that. I only want the (public) pool to assign IPs if the device is connected through that one open AP, and deny any other unknown clients that connect through any other means.
> Is that possible?

To do what you want as written will need a managed switch that can add circuit-id to DHCP requests, then you can manage pool availability from that.
But - this is rubbish from a security PoV. Unless you have other measures in place (in which case I doubt you'd be asking the question) then any client can manually configure an address and access the network - and finding out the required details is fairly trivial to do.

I would suggest some re-engineering of the network would be a better course of action.
Split the guests off onto a separate network - then you can stop them accessing your internal network as they can right now. Then DHCP would simply manage it as two different subnets. To do that just needs a spare port on a router.

Better would be to offer both networks across all the APs. Many APs support multiple SSIDs (wireless networks), using a different VLAN for each SSID. With a managed switch, you trunk the VLANs required to the AP, and it's logically much the same as having multiple switches and multiple sets of APs - again from the DHCP PoV it's just two (or more) subnets.

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