Create a user for ktrl and add it to the input groups
```
sudo useradd -r -s /bin/false ktrl
sudo groupadd uinput
sudo usermod -aG input ktrl
sudo usermod -aG uinput ktrl
# If you're using the sound feature
sudo usermod -aG audio ktrl
```
Add a new udev rule
```
sudo touch /etc/udev/rules.d/99-uinput.rules
```
Add the following line to it
```
KERNEL=="uinput", MODE="0660", GROUP="uinput", OPTIONS+="static_node=uinput"
```
If you are using the default `/opt/ktrl` directory -
```
sudo chown -R ktrl:$USER /opt/ktrl
sudo chmod -R 0770 /opt/ktrl
```