udm fan post

content/blog/2022-04-06-udm-fan.md

@@ -0,0 +1,66 @@
+---
+layout: page
+title: "Making my UDM-Pro scream" 
+description: "Remote fan control for the Unifi Dream Machine Pro"
+date: 2022-04-06
+tags: random
+draft: false
+extra:
+  uses_katex: true
+  excerpt: A project review post covering my work on remote-control for the UDM-Pro cooling system
+---
+
+[Ubiquiti](https://www.ui.com/)'s [Unifi Dream Machine Pro](https://www.ubnt.com/products/unifi-dream-machine-pro) is a powerful medium-scale business-oriented rack-mount router, capable of handling 10/100/1000/10000 ethernet traffic. Really quite a nice device.
+
+One day, I had the thought: *I've never heard the fans ramp up on this*. And so, I started looking into the possibilities of manual fan control.
+
+As it turns out, this Linux-based device allows you (like any embedded Linux computer) override its I/O with some clever shell commands.
+
+## Enter: SSH
+
+If you own a UDM-Pro, you surely know how to log in to it via SSH. If not, look it up :smile:.
+
+With an SSH connection open, the following commands let you control the fans on the device!
+
+```sh
+# Override the fans with a speed (0-255)
+export FAN_SPEED=128
+killall -9 S04ubnt-fan-speed ubnt-fan-speed
+echo 1 > /sys/class/hwmon/hwmon0/device/pwm1_enable
+echo 1 > /sys/class/hwmon/hwmon0/device/pwm2_enable
+echo $FAN_SPEED > /sys/class/hwmon/hwmon0/device/pwm1
+echo $FAN_SPEED > /sys/class/hwmon/hwmon0/device/pwm2
+
+# Return control back to the device
+/etc/init.d/S04ubnt-fan-speed start
+```
+
+## Exit stage left
+
+Who needs SSH anyways? 
+
+When I discovered this, I decided to write a little program that wraps the SSH commands with a little bit of error checking, and support for auto-discovery of UDM-Pro devices on your network.
+
+{{ github(repo="ewpratten/udm-fan") }}
+
+<br>
+
+The following commands can be used to control the fans on a local UDM-Pro:
+
+```sh
+# Set the fans to half speed
+udm-fan set 128
+
+# Set the fans to full speed (with a custom IP address)
+udm-fan set 255 --override-ip 172.16.11.5
+
+# Bring the fans back to automatic control
+udm-fan auto
+```
+
+Passwords can be provided through:
+
+- The `--ssh-password` flag
+- The `UDM_SSH_PASS` environment variable
+- A `.netrc` entry with the hostname being the UDM's IP address
+- The terminal at runtime