Quick setup Network UPS Tools (NUT) Server on Debian 10

After several power outages I finally decided to by a small UPS (USV) for my homelab. I don’t like when my IT infrastructur, especially the Synology NAS, gets switched off without a normal shutdown. So I bought a new EATON 5P 650 UPS to cover my NAS and server.

I started trying to use the Synology Diskstation as a NUT server. Usually the NAS can do this by default. You just attache the UPS via usb to the NAS and activate the function. Everything seems working fine. The problem was, it works locally. But you could not connect to the NUT server from another machine. I tried to connect from an ESXi 6.7 U3 host with installed NUT-Client and from an Windows Server 2019, both couldn’t connect. The ESXi hosts said „Error: Access denied“ so I tried to connect via telnet.

telnet nut-server-ip-address 3493

With telnet I get a connection, but when it comes to login with the username, there is also an access denied. After many hours trying to fix thie access problem I gave up. The funny thing is, after all this I setup a new NUT Server on an Debian VM in under 15 min.

NUT package (nutd and upsmon)

Plug-In the UPS USB-Connection to the host. In my case I connected it to the ESXi host and configured a this new virtual usb device in the Debain VM. You also can use a normal computer with Debian 10 installed.
Install the NUT package with the apt package manager
```
sudo apt-get install nut
```

Make some configurations and changes in the nut directory /etc/nut

# /etc/nut/
drwxr-xr-x 2  root nut  4096   Jan 11 00:49 .
drwxr-xr-x 94 root root 4096   Jan 10 23:54 ..
-rw-r----- 1  root nut  1543   Jan 11 00:01 nut.conf
-rw-r----- 1  root nut  5571   Jan 11 00:12 ups.conf
-rw-r----- 1  root nut  4595   Jan 11 00:01 upsd.conf
-rw-r----- 1  root nut  2177   Jan 11 00:03 upsd.users
-rw-r----- 1  root nut  15362  Jan 11 00:16 upsmon.conf
-rw-r----- 1  root nut  3887   Jun  1  2018 upssched.conf

In the nut.conf file we change the MODE to netserver
```
# /etc/nut/nut.conf
MODE=netserver
```
In the ups.conf we need to configure the right drivers for the UPS. In my case I knew what to configure, because the Synology NAS made the right configuration. You can get a compatibility list from the NUT-Server on https://networkupstools.org/stable-hcl.html
We make a new section for the UPS like in this example. As my UPS is connected via usb the port configuration can be set to auto. If you connect the UPS via a serial cable you need to configure it different.
```
# /etc/nut/ups.conf
[eaton]
    driver = usbhid-ups
    port = auto
```
The name in the brackets can be anything you like to identify the ups. I used eaton as the name related to the manufacturer. In bigger setups you may like to name it like [serverups] …
After setting up the right drivers we can make sure that the NUT-Server detects the UPS.
```
upsdrvctl start
```
The output should look like this
```
Network UPS Tools - UPS driver controller 2.7.4
Network UPS Tools - Generic HID driver 0.41 (2.7.4)
USB communication driver 0.33
```
The upsd.conf has a LISTEN section. We need to configure it with the server ip-address so we can connect to the NUT-Server from other clients.
```
# /etc/nut/upsd.conf
LISTEN 192.168.0.123
LISTEN 127.0.0.1 3493
LISTEN ::1 3493
```
In my example I’ve added the first ip-address (192.168.0.123). There is no need to write the port behind the address (3493) unless you want to change the default port.
After that we need to make a new user in the upsd.user file
```
# /etc/nut/upsd.user
[upsmon]
       password = supersecretpassword
       upsmon master
```
You should add multiple users for the server an client. See the man page for upsd.users for more information.

Now we configure the upsmon.conf there we need to add a MONITOR master

# /etc/nut/upsmon.conf
# MONITOR     ("master"|"slave")
# 
#  is an integer - the number of power supplies that this UPS
# feeds on this system. Most computers only have one power supply, so this
# is normally set to 1. You need a pretty big or special box to have any
# other value here.
# 
MONITOR eaton@192.168.0.123 1 monuser supersecretpassword master
#
POWERDOWNFLAG /etc/killpower
SHUTDOWNCMD "/sbin/shutdown -h now"

As the system name us us the value in the brackets you made in the ups.conf the user and password was configured in the upsd.user file.

Since we don’t want that other users can read this secret files we fix the permissions for our needs.
```
$ sudo chown root:nut /etc/nut/*
$ sudo chmod 640 /etc/nut/*
```
At the end whe should reload both services upsd and upsmon. This can be done like this

Testing a local Client request

Now we can test if the NUT-Server works locally. In my case the name of my instance is [eaton]. Therfore I’ll make client request to this the instance name eaton.

upsc eaton

If everything works fine we get an output similar like this

Init SSL without certificate database
battery.capacity: 9.00
battery.charge: 100
battery.charge.low: 20
battery.charge.restart: 0
battery.charger.status: floating
battery.energysave: no
battery.energysave.delay: 300
battery.energysave.load: 5
battery.protection: yes
battery.runtime: 1575
battery.type: PbAc
battery.voltage: 13.7
battery.voltage.nominal: 12
device.mfr: EATON
device.model: 5P 650
device.serial: G114L41071
device.type: ups
driver.name: usbhid-ups
driver.parameter.pollfreq: 30
driver.parameter.pollinterval: 2
driver.parameter.port: auto
driver.parameter.synchronous: no
driver.version: 2.7.4
driver.version.data: MGE HID 1.39
driver.version.internal: 0.41
input.current: 0.70
input.frequency: 49.9
input.frequency.extended: no
input.frequency.nominal: 50
input.sensitivity: normal
input.transfer.boost.low: 184
input.transfer.high: 294
input.transfer.low: 160
input.transfer.trim.high: 265
input.voltage: 235.9
input.voltage.extended: no
input.voltage.nominal: 230
outlet.1.autoswitch.charge.low: 0
outlet.1.delay.shutdown: 65535
outlet.1.delay.start: 3
outlet.1.desc: PowerShare Outlet 1
outlet.1.id: 1
outlet.1.status: on
outlet.1.switchable: yes
outlet.2.autoswitch.charge.low: 0
outlet.2.delay.shutdown: 65535
outlet.2.delay.start: 6
outlet.2.desc: PowerShare Outlet 2
outlet.2.id: 2
outlet.2.status: on
outlet.2.switchable: yes
outlet.desc: Main Outlet
outlet.id: 0
outlet.switchable: no
output.current: 0.60
output.frequency: 49.9
output.frequency.nominal: 50
output.powerfactor: 0.53
output.voltage: 235.9
output.voltage.nominal: 230
ups.beeper.status: enabled
ups.delay.shutdown: 20
ups.delay.start: 30
ups.efficiency: 86
ups.firmware: 02.14.0026
ups.load: 21
ups.load.high: 105
ups.mfr: EATON
ups.model: 5P 650
ups.power: 142
ups.power.nominal: 650
ups.productid: ffff
ups.realpower: 76
ups.realpower.nominal: 420
ups.serial: G114L41071
ups.shutdown: enabled
ups.start.auto: yes
ups.start.battery: yes
ups.start.reboot: yes
ups.status: OL CHRG
ups.test.interval: 2592000
ups.test.result: Done and passed
ups.timer.shutdown: 0
ups.timer.start: 0
ups.type: offline / line interactive
ups.vendorid: 0463

I hope I could help you make a basic NUT-Server setup for your homelab.