I have my modem and pfSense router connected to an uninterruptible power supply (UPS) - useful if you live in California with plenty of power outages. Most UPS units beep when they are on battery power during power outages. Assuming that you have enabled email notifications for the UPS (Services → UPS → UPS Settings → General Settings → Enable E-Mail notifications), it is not really necessary since you will receive an email and the beeping is just annoying. In this guide, I show how to disable the beeps using pfSense.

I assume that the UPS is connected via USB and is recognized by pfSense. In Services → UPS → UPS Status you should see a bunch of information about the UPS if that is the case.

You need the UPS name which is defined in Services → UPS → UPS Settings → UPS Name. Then you need to get the admin password for the UPS. pfSense will automatically generate one, but you can’t see it in the UPS section of the web UI. Go to Diagnostics → Command Prompt and use Execute Shell Command to execute the command cat /usr/local/etc/nut/upsd.users. It will print the UPS user configuration. Take note of the password in the [admin] section of the file. You will need that to authenticate the upscmd command below.

Let’s assume the UPS name is router-ups and the admin password is ncf3c2op. Execute the following three commands using the pfSense Execute Shell Command functionality:

upsc router-ups ups.beeper.status
# Returns: enabled

upscmd -u admin -p ncf3c2op router-ups beeper.disable
# Returns: OK

upsc router-ups ups.beeper.status
# Returns: disabled

The beeps should now be disabled. If the above doesn’t work, the command upscmd -l router-ups will list all available commands for this UPS. Check whether disabling beeps is a supported command for your UPS.