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We have devices that get their IP addresses via DHCP. Those devices are up 24/7 until they have a power loss or restart due to other activities (hardware watchdog etc.)

Unfortunately the devices do not renew the DHCP lease while they are up and running. Therefore it's very likely that the lease expires and they get a different IP address once something unexpected happens (power loss, reboot, ...). This makes it even harder to troubleshoot.

DHCP is managed by our externalized IT department and they are neither happy providing static IP addresses nor configuring DHCP in a way that our devices get the same IP address every time (reservation). It takes weeks until such a request is processed.

So, independent of the fact whether I'll be allowed to use such a tool, I wonder whether it exists:

  • spoof a DHCP request for a list of MAC addresses (any common format is ok) so that the lease time will be extended
  • no UI interaction required, so I can run it by task scheduler
  • for Windows
  • price less than 20 €

Technically, it seems that requesting a specific IP is done with DHCP Option 50 (see RFC 2132, chapter 9.1).

  • You have a larger issue that a device is not going to solve: the way the people in your organization work together. – Jan Doggen May 9 '16 at 7:57
  • @JanDoggen: that's true. It began with outsourcing of the IT department. – Thomas Weller May 9 '16 at 9:36
  • But that still means that your company gives the instructions to the outsourced entity, doesn't it? Someone in your company fails to order it to do so, i.e. the issue is still within your company. – Jan Doggen May 9 '16 at 10:12
  • I am not sure if this is exactly what you are looking for.. On windows systems you can extend the lease by running ipconfig /renew will extend the lease. So you could run the command repeatedly after a given interval of time using the Task Scheduler built into windows itself. Have you considered this? Please check if using ipconfig /renew extends the lease for your devices. – Aswin P J May 9 '16 at 14:01
  • @AswinPJ: ipconfig /renew works for the machine itself. However, there's no option to pass a MAC address of a different computer, is there? I tried ipconfig /? but I could not find an option which would allow that. I can't run that command on the device itself. It's an embedded device. – Thomas Weller May 9 '16 at 14:43

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