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I have a remote Windows 2012R2 server that runs a lot of important stuff. I, stupidly, accidentally, did an ipconfig /release on that server from the other side of the continent. Now that server no longer has an IP address and I have no way of accessing it. There is nobody nearby with physical access.

I have full access to literally everything on that network, but I can not figure out any way to have it refresh its IP address or reboot. I have admin access to:

  • the DNS server
  • the DHCP server
  • the AD DC server
  • the router
  • guest Hyper-V machines that are still running on that server
  • other random workstations on the domain
  • the MAC address of the server in question

The only thing I don't have is a remote power switch to reset the damned server. I'm travelling for a month and I desperately need this server up, but I seem to have screwed myself so hard with this that there is no recovery. Does anyone have any ideas of any way to force this thing to renew its IP address or reboot?

This question has been marked as a duplicate, but it really is not. The other question is about steps to prevent situations like the one I am in to happen. But my question is, once I have lost contact with my remote machine, is there anything that can be done, given the considerable amount of information I have about the LAN of the remote machine? Is there for instance a generalization of a magic packet technology which can restart a machine, or something similar?

In other words: given that I am already stuck, is waiting my only option?

UPDATE: turns out that the ipconfig /release only released the IPv4 address, but it still had an IPv6 address. Once I found that from looking through the router logs, I was able to reboot it using that and the shutdown -r -m \\IPv6Address command.  

EDITOR'S NOTE (Scott): Note that this solution (and the others suggested in the comments below) is irrelevant and not applicable to the question of which this one is allegedly a duplicate.

Jordan
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  • You're out of luck until someone reboots it or at least refreshes the DHCP. This is what [Out Of Band Management](https://en.wikipedia.org/wiki/Out-of-band_management) is for. – Ƭᴇcʜιᴇ007 Jun 14 '15 at 18:45
  • I have about 2% of an idea here (or maybe I should say, an idea that is 2% of an answer): if (1) you have administrator access to another host on the same LAN segment, and (2) you know your “important” server’s MAC address, it seems that you could send packets addressed to the important machine by MAC but with a broadcast (or possibly multicast) IP address.  Even if the target machine doesn’t have *any* IP address, it seems that [255.255.255.255 should work](https://en.wikipedia.org/wiki/Broadcast_address).  As long as the interface is still up,  … (Cont’d) – Scott - Слава Україні Jun 14 '15 at 20:26
  • (Cont’d) …  I believe that this should get traffic into your machine’s network stack.  Even if this works, you will probably be restricted to UDP (or lower; e.g., raw IP, or even raw Ethernet) — I doubt that you can establish a TCP connection with a machine with no IP address.  I don’t know what you could send that would be useful.  Does the machine support Wake-on-LAN or anything similar?  Does it support remote management (e.g., cPanel)?  I don’t know whether either of these would be useful; I’m just suggesting them as starting points for other people’s brainstorming.  … (Cont’d) – Scott - Слава Україні Jun 14 '15 at 20:27
  • (Cont’d) …  Also, at the risk of asking a dumb question, are you currently able to login to a virtual machine that is running on your “important” server?  If so, can you then login to the physical machine through an Internal Virtual Switch (Hyper-V’s analog to VirtualBox’s “Host-Only Network”)?  If you can do that, then you’re home free, right?  (Suggestion: Try `ipconfig /renew` (or whatever the appropriate command is) first.  Obviously, rebooting means that your VMs go away, unless they autostart on boot.) – Scott - Слава Україні Jun 14 '15 at 20:27
  • @Scott Connecting through the virtual switch is a good idea. I had already found a workaround by the time I read this though so I didn't get to test it (see OP). – Jordan Jun 14 '15 at 23:59
  • @Jordan: I'm glad you solved your problem.  I voted to reopen the question.  Watch this space; if enough people agree, you'll be able to post your solution *as an answer*. – Scott - Слава Україні Jun 15 '15 at 03:05

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