Airport Router DHCP Client Identification

Question

I have a 3rd Gen Airport Extreme (802.11n 3rd Gen Dual band) as my main router. Attached to it are an Airport Express (802.11n 1st Gen Single Band) which is connected by and extends WiFi over it's wired ethernet, and also an Airport Extreme (802.11n 2nd Gen Single Band) which extends wirelessly. I run a dual band network, the 2.4GHz network which is extended over the 2 slave devices (for want of a better description), and the main router also has a 5GHz network as it is a dual band router, and the guest network (which is an open network, no security).

In Airport Utility on iOS devices (I don't currently have access to a Mac to test the OS X application) I can select a device, select Wireless Clients, and list any clients that are connected to that particular device (from an access point perspective).

One problem with this is not seeing how can I identify which device is being shown in the list? Most attached devices will happily have a real description, namely iOS devices, Macs and some PCs etc, but I have a whole load of devices for which I cannot easily identify what is being connected. For example:

• I sometimes just get the DHCP lease IP address shown as the client

• I sometimes get a name that I don't recognise, i.e. Sue's iPhone or android-653246a714bc41f

• I sometimes get the MAC address only

• Sometimes (today, after I added a new access restriction) all the proper DHCP Client ID names are replaced with the MAC address for periods of time, and sometimes MAC addresses are shown when the client (example, Apple TV and Playstation 3) is in a WOL enabled sleep mode - still connected on the "physical" layer, but with no IP address assigned.

My reasons for wanting to do this are varied:

• The Airport Express has a limit of the number of connections that can be made to it, so it might be nice to move some devices to another access point to relieve strain on it

• Being a bit fussy, I like to be able to identify what is what generally

• I have reasons for leaving the guest network open in terms of security (some old devices that only support WEP, some devices are such a pain to type passwords into like my TV receiver box that I simply don't wish to spend 20 minutes faffing entering a very lengthy password via a TV remote control unit...). I know some people (Sue, and her iPhone) use my guest network without my permission, and I wanted to use access control to block these people as and when I see them use the network.

So, the problem for which I am asking this question is as follows:

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• How can I make the router set or remember a descriptive name for all devices, not just those that response to DHCP Client ID requests?
  • Sub question: How can I see all current DHCP leases, not just currently connected clients?

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I have tried to use DHCP reservations against a PC that only ever shows up with the MAC address, to see if it wil then pick up the description, and it doesn't seem to.

I have set a year long lease on my DHCP, so should be able to identify individual devices with some accuracy etc to stop devices sharing an IP address

Everything uses DHCP, the only hardcoded IPs are the routers themselves.

Answer 1

It seems there is no way to force a client ID at the router end, so you have to make do with setting it right on the client. I discovered that my Apple TV and Playstation has spaces in the names that prevented them from setting the ID properly. Taking the spaces out made them show up properly. However, some clients manage to register names correctly with spaces, so I guess it's down to the implementation of the IP stack on the client device rather than a server issue.

It's also worth noting that after updating settings or resetting the routers, it appears to show just MACs until it has time at some point doing a lookup against it to set the ID. I found no way of working out how long this is, seems to be random.

It's also worth noting that some devices that are able to use Wake On LAN over wifi and that are currently in a sleep state will register at a Physical layer, so the router is able to send the relevant command to wake it, and as such the MAC is shown, but no IP (and hence no active DHCP use to pull the ID) until the device wakes and pulls it's IP/registers it's client ID.

Finally, using an old version (5.6.1) of Airport Utility it is possible to view a DHCP lease list of all clients, not just active wireless connections. Sadly it doesn't work on Mavericks, but you can bodge it to make it work. Unfortunately, either it does not track the DHCP leases for the guest network, or the lease length (not configurable) is short so pretty much only actively connected guests are shown in this list.