APC MasterSwitch Controllers

Our racks have APC MasterSwitch units installed. These allow us to turn on and off the power to particular plugs. While the BMC is ususally a better way to do power control, some machines (old 1U servers) do not have BMCs, or the BMC may be the problem.

There are two APC units, one for each rack. They are apc-left and apc-right, labeled by which rack they are in as you face the front.

Magellan’s Scripting

/usr/local/bin/set-power knows how to manipulate the controllers we use. It is exported via remctl running on Magellan.

If you need to know the password to a strip controller, use /usr/local/bin/set-power.show-password on Magellan. It knows how to use the HMAC-based password scheme we use.

APC Configuration

The controllers can be accessed via serial or telnet (we keep the web interfaces disabled). Once you’re there, log in with username apc and password derived via our scheme. You are then able to navigate a menu.

Naming outlets

Once you get to a list of outlets, you’ll note that they can be named (and some are). Each outlet should be named for the machine which is plugged in to it. To rename an outlet, starting just after selecting the outlet:

  • Press 2 - configure
  • Press 1 - Outlet Name
  • Type in the new name
  • Press 5 - Accept Changes

And you’re done. Keeping the names of the outlets up to date will be extraordinarily helpful in not missing if someone needs to force reboot a server.

Factory Restore Over The Network

Thanks to http://mccltd.net/blog/?p=36 for this section.


Do not put your APC MasterSwitch controllers on public networks. This can not be stated emphatically enough.

Telnetting to your APC device, or connect over the serial port, and using the password TENmanUFactOryPOWER (very clever; any user name will do) will get you the Factory Menu. Entering 13 will bring you to an EEPROM dumping tool which accepts hex addresses; usernames and passwords will be readable near 1d0.

Apparently it is also always possible to use apc as both the user and password within the first 30 seconds of the device being powered on. Oi.