Phantom DHCP Clients

[scotthobbz]

I have a DIR-628 d-link router. I've been having some issues with devices not being able obtain an IP address. Typically this can be resolved by rebooting the router. I became interested in understanding "why" and started spending time on the routers admin site. It looks like there's an issue where the range of available IP addresses is consumed by devices with no MAC address and a lease expiration duration of "never". After a reboot the client list is small (about 5 devices, all of them recognizable) but eventually I see one with a MAC address of 00:00:00:00:00:00 and then another, another...and so on. Any ideas? Thanks in advance.

 

[bill001g]

If they know there is this bug with their firmware then it should have been fixed. That is not how DHCP is suppose to operate. Even if a DHCP server were to accept all zero mac it should then give out the same ip over and over for that mac just like it does for any other mac.

 

[scotthobbz]

If they know there is this bug with their firmware then it should have been fixed. That is not how DHCP is suppose to operate. Even if a DHCP server were to accept all zero mac it should then give out the same ip over and over for that mac just like it does for any other mac.

Thanks Bill. I completely agree with your statements. It's possible I should have been more clear about "router's admin site". I do mean, 192.168.0.1 on my LAN and I discovered the issue that way. I'm uncertain if d-link knows about this particular issue or not. I'm running the latest firmware and can't find anything on their support site regarding the matter.

 

[bill001g]

Unfortunately you do not have my normal recommendation when factory firmware is being a pain since this router does not support any of the more well known third party firmware loads.

The router controls the lease time. It should not be possible for a end device to insert a permanent dhcp lease. Some routers you can define these static mappings but you can never have the same mac address assigned multiple ip's

This has to be a bug in the router. You could I suppose assign static IP in the end user devices and just ignore what the router does having a mapping in the DHCP table does not mean you can not use that IP on a machine. Your other option if it allows it is to change the subnet mask on the lan. You could always use 10.0.0.0/8 The router would never run out of ip in that range.....but it would likely crash when it runs out of memory to store them.