topic Re: DHCP duplicate addresses in General Topics

DHCP duplicate addresses

rclary — Mon, 17 Oct 2011 18:45:01 GMT

PA-500, PANOS 4.0.5, DHCP set to "auto", lease time all zeros, one IP pool (192.168.2.2-192.168.2.126) .

Recently I noticed that I was getting duplicate IP messages from Windows computers on my network. I found that certain devices were geting the same IP. I found that when plugging in two devices both got the same IP address.

Has anyone else seen this? It appears that a lease time of zero started behaving like a lease time of zero instead of unlimited. I have another PA-500 configured the same way with no problems.

Setting a lease time fixed my problem, but I'm curious why after more than a year of use the behavior would change, and why my other PA-500 behaves differently.

Re: DHCP duplicate addresses

ncampagna — Tue, 18 Oct 2011 20:07:11 GMT

Hi RClary,

Did you observe this change of behavior around the time that you upgraded PAN-OS? If so, what version were you on before 4.0.5? It looks like you have a pool of 124 IP addresses, do you have the same number of devices?

Thanks,

Nick

Re: DHCP duplicate addresses

rclary — Mon, 24 Oct 2011 10:35:23 GMT

No upgrade, before I noticed the behavior. I was running 4.0.2 since its release date (4/11) and only started seeing the behavior in the past month. I downloaded and installed 4.0.5 with no change.

Normally I have fewer than 20 devices. I used the command line to clear all leases, and tested it with a network consisting of one switch and two devices, both devices got the same address.

Re: DHCP duplicate addresses

ncampagna — Tue, 25 Oct 2011 22:56:38 GMT

Please open a case with our support team to investigate.

Thanks,

Nick

Re: DHCP duplicate addresses

paloalto_exn — Mon, 09 Jan 2012 15:27:15 GMT

Hello,

I have a customer which complains the same problem in a 4.0.5 box. An interface dedicated to Wifi guest access.

He complains to have some machine with IP address in conflict and the following error in the PAN system log:

SYSTEM ALERT : medium : ip address is already in use ip x.x.x.x interface ethernet1/3

The lease configured is 4 hours.

Have you fixed that issue or is a bug?

Thank you and regards.

Walter Doria.