Network UPS Tools

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This document describes how to install the Network UPS Tools (NUT). Network UPS Tools is compatible with thousands models of UPS. You can check the Hardware Compatibility List to see if your UPS is supported.

Installation of Network UPS Tools

You can install network-ups-tools with the nut package.


NUT has 3 daemons associated with it:

  • The driver which communicates with the UPS.
  • A server (upsd) which uses the driver to report out the status of the UPS.
  • A monitoring daemon (upsmon) which monitors the upsd server and takes action based on information it receives.

The idea is that if you have multiple systems connected to the UPS, one can communicate the status of the UPS over the network and the others can monitor that status by running their own upsmon services. NUT has extensive documentation on the configuration however this is going to walk through a simple setup of a USB UPS and the associated server and monitor all in one system (common desktop configuration).

Driver configuration

The configuration here will depend on the type of UPS you have. Consult the previously mentioned Hardware Compatibility List to find what driver will likely work for your UPS. You can run the tool nut-scanner(8) which will detect NUT-compatible devices attached to your system.

For many UPS connected by USB, use the usbhid-ups(8) driver. For UPS with serial port, use port=/dev/ttySX, where X is the number of serial port (Example:/dev/ttyS1). For UPS with USB port, use port=auto.

    driver = usbhid-ups
    port = auto

You can name the UPS device whatever you like. ups.conf(5)

Start the driver as root with upsdrvctl start. If there's no errors, you should see a message like this one for the driver usbhid-ups:

Network UPS Tools - Generic HID driver 0.34 (2.4.1)
USB communication driver 0.31
Using subdriver: MGE HID 1.12
Detected EATON - Ellipse MAX 1100 [ADKK22008]

If the driver doesn’t start cleanly, make sure you have picked the right one for your hardware. You might need to try other drivers by changing the "driver=" value in ups.conf.

Can't claim USB device error

If you receive an error message like this one:

Can't claim USB device [XXXX:YYYY]: could not detach kernel driver from
interface 0: Operation not permitted
Driver failed to start (exit status=1)

Or a less specific one:

USB communication driver 0.33
No matching HID UPS found
Driver failed to start (exit status=1)

It's most likely a problem with permissions for accessing the device. You can fix that by specifying an udev rule that sets the correct group:

SUBSYSTEM=="usb", ATTR{idVendor}=="XXXX", ATTR{idProduct}=="YYYY", SYMLINK+="ups0", GROUP="nut"

Where idVendor and idProduct are the device manufacturer and product ID. You can see these either in the error output [XXXX:YYYY] or by using lsusb.

Note: SYMLINK here is an optional rule for adding a symlink to the device for convenience (in this case it will show up in /dev/ups0 when connected).
Note: The nut group is added by the NUT AUR package. If you used different installation method (or the package perhaps changed) you may need to correct the group. Alternatively you could also set the device accessible by anyone with MODE="0666".

After this is done, reload and retrigger udev rules by issuing this command:

# udevadm control --reload-rules && udevadm trigger

upsd configuration

By default upsd listens only on localhost and this is fine for our purpose. Though it is not necessary for following this guide, you can configure upsd beyond the defaults by editing /etc/nut/upsd.conf. See upsd.conf(5).

You will need to add a user for a monitor to connect to the server and issue commands. See upsd.users(5).

     password = password
     upsmon master
     actions = SET
     instcmds = ALL

At this point you should be able to start/enable nut-server.service which will automatically start nut-driver.

If it has started successfully, you can run upsc <upsname> to get information from the UPS. Example output from the command:

battery.charge: 100
battery.charge.low: 10
battery.charge.warning: 20 CPS
battery.runtime: 5550
battery.runtime.low: 300
battery.type: PbAcid
battery.voltage: 13.5
battery.voltage.nominal: 12
device.mfr: CPS
device.model: UPS CP1000AVRLCD
device.type: ups usbhid-ups
driver.parameter.pollfreq: 30
driver.parameter.pollinterval: 2
driver.parameter.port: auto
driver.parameter.synchronous: no
driver.version: 2.7.4 CyberPower HID 0.4
driver.version.internal: 0.41
input.transfer.high: 140
input.transfer.low: 90
input.voltage: 122.0
input.voltage.nominal: 120
output.voltage: 122.0
ups.beeper.status: disabled
ups.delay.shutdown: 20
ups.delay.start: 30
ups.load: 0
ups.mfr: CPS
ups.model: UPS CP1000AVRLCD
ups.productid: 0501
ups.realpower.nominal: 600
ups.status: OL
ups.test.result: Done and passed
ups.timer.shutdown: -60
ups.timer.start: 0
ups.vendorid: 0764

upsmon configuration

The last step is to configure upsmon to listen to upsd and take action on events.

Add the following line to /etc/nut/upsmon.conf:

MONITOR upsname@localhost 1 upsduser password master

Here upsname is the name of the UPS, and upsduser and password is the user and its password you set in /etc/nut/upsd.users.

You can also configure what alerts are sent, where they are sent, what action is taken when the battery is low, and more. See upsmon.conf(5).

Then start/enable nut-monitor.service.

Your logs should show upsmon starting and monitoring the UPS.


NUT-Monitor is a graphical user interface to monitor and manage devices connected to the Network UPS Tools server.

You can install nut-monitor with the nut-monitorAUR package.