Lan Sleep/Wake Up Tool

I write small tools from time to time that I need to manage my personal lab. Since my machines are in their own powered and air conditioned closet, it isn’t very convenient to get up, open the closet, get slammed by the noise, and turn a machine on. And, I don’t want to leave them on all the time if I’m not using them. I’m no Paul Randal (blog|twitter) but I do use between 4000 and 5000 kilowatt hours a month.

Enter Innovation!

So, since I couldn’t find a simple tool to handle this, I wrote one! LabWakeUp is pretty easy to use.

Don’t blink, you might miss it.

It looks for a text file called servers.txt. This file should have one server name per line. The program loops through them and tries to get a MAC address via a system call (a.k.a. P/Invoke) to the Windows DLL that handles ARP calls. It then writes these to another text file called serverMACs.txt that has, you guessed it, a server name and a MAC address if one could be found. You can manually put entries in this file if you like. I personally don’t like hunting around for MAC addresses then typing them into anything if I don’t have to. You only need to fill in the Windows user name and password if you want to wake a machine up.

They are Undocumented Features!

When you start it up, nothing is displayed while it goes through the servers.txt file. Again, lazy strikes, I may fix it later - it is just annoying and not a “bug”. In serverMACs.txt, if a server isn’t found, it may be a bogus MAC address. This is most defiantly a bug and will be addressed. The serverMACs.txt isn’t updated if a new MAC is found. You have to delete the entry and let it rediscover it.

Improvements are Coming… Eventually!

• Asynchronous multi-threaded MAC discovery. This will grey out a portion of the tool but will make things more tolerable.
• Discover MAC on new entries only. So, if there aren’t any new names in servers.txt, we won’t do the MAC lookup.
• Update MAC entries. Yep, just update the MAC entries that we know about.

Finally…

If you end up using this tool, let me know! I’d like to think that some of the things I build are useful to others too.