mirror of
https://gitlab.com/EternalWanderer/voidcruiser.nl
synced 2024-11-28 20:03:50 +01:00
PWR switch post
This commit is contained in:
parent
ad6d79d539
commit
19571ee383
143
content/rambles/pwr-switch.md
Normal file
143
content/rambles/pwr-switch.md
Normal file
|
|
@ -0,0 +1,143 @@
|
|||
---
|
||||
title: "PWR Switch"
|
||||
date: "2022-10-14T10:50:56+02:00"
|
||||
author: "$HUMANOID"
|
||||
tags: ["linux", "ssh", "iot"]
|
||||
description: "Hacked together IOT setup with some semblance of security"
|
||||
---
|
||||
|
||||
# Introduction
|
||||
|
||||
As we all know, the "S" in IOT stands for security.
|
||||
We've all seen countless stories of people's networks getting hijacked due to some 3 year old vulnerability in the software stack of their *insert smart device here*.
|
||||
These things barely get any patches at all.
|
||||
On top of that, the most they do is spy on you and send [your footage to the police without asking for your consent](https://edition.cnn.com/2022/07/14/tech/amazon-ring-police-footage/index.html "Load without JS to make the page behave.").
|
||||
|
||||
Still, on the other hand, it can be really convenient to be able to control some of the electronics in your home without having to walk towards them.
|
||||
I personally have a lamp that I frequently forget to turn off when leaving my room.
|
||||
The solution was an [Olimex PWR-switch](https://www.olimex.com/Products/Duino/Shields/PWR-SWITCH/) in combination with a Raspberry Pi 4 that I have running 24/7 regardless (mostly to watch YouTube videos and listen to music over my speaker set; I might write a post about this beautifully hacky contraption at some point in the future).
|
||||
|
||||
# Setup
|
||||
|
||||
Setting it up was relatively easy.
|
||||
|
||||
First I connected my lamp to a European extension cord socket to a random power cable I still had laying around.
|
||||
Then I hooked that up to my PWR-switch and plugged my lamp into that contraption.
|
||||
|
||||
From there I got little bag of jumper wires from my local electronics store and hooked up the PWR-switch to my Raspberry Pi.
|
||||
I hooked up the PWR-switch's positive to `GPIO 15` and it's ground to the preceding `ground` pin.
|
||||
[Here's](https://pinout.xyz) a reference page.
|
||||
|
||||
_Note_, `GPIO 15` is in reference to pin number 10 and the preceding ground pin is pin number 6.
|
||||
|
||||
From there I looked up how to send power to `GPIO 15` in order to have it switch to on.
|
||||
The first step to this end is to initialise the pin.
|
||||
This can be done with:
|
||||
```sh
|
||||
echo 15 > /sys/class/gpio/export
|
||||
echo out > /sys/class/gpio/gpio15/direction
|
||||
```
|
||||
Then, sending power to it can be done using something like...
|
||||
```sh
|
||||
echo 1 > /sys/class/gpio/gpio15/value
|
||||
```
|
||||
...and the opposite can be done using:
|
||||
```sh
|
||||
echo 0 > /sys/class/gpio/gpio15/value
|
||||
```
|
||||
|
||||
Deinitialising the pin can be done with:
|
||||
```sh
|
||||
echo 15 > /sys/class/gpio/unexport
|
||||
```
|
||||
To make this all a little easier I have written a wrapper in POSIX Shell:
|
||||
{{< start-details summary="Click to see script" >}}
|
||||
```sh
|
||||
#!/bin/sh
|
||||
|
||||
INIT_PIN(){
|
||||
# the PWR-SWITCH is connected to GPIO 15 and the preceding ground pin
|
||||
# reference page https://pinout.xyz/pinout/
|
||||
[ -d /sys/class/gpio/gpio15 ] && echo "Pin already initialised" && exit 0
|
||||
echo 15 > /sys/class/gpio/export
|
||||
echo out > /sys/class/gpio/gpio15/direction
|
||||
}
|
||||
|
||||
DEINIT_PIN(){
|
||||
[ -d /sys/class/gpio/gpio15 ] || echo "Pin not initialised" && exit 0
|
||||
echo 15 > /sys/class/gpio/unexport
|
||||
}
|
||||
|
||||
PIN_STATUS(){
|
||||
if [ -d /sys/class/gpio/gpio15 ] ; then
|
||||
echo "pin status: Pin initialised"
|
||||
else
|
||||
echo "pin status: Pin not initialised"
|
||||
fi
|
||||
}
|
||||
|
||||
SWITCH_ON(){
|
||||
# initialise pin before doing anything
|
||||
[ -d /sys/class/gpio/gpio15 ] || INIT_PIN
|
||||
echo 1 > /sys/class/gpio/gpio15/value
|
||||
}
|
||||
|
||||
SWITCH_OFF(){
|
||||
# initialise pin before doing anything
|
||||
[ -d /sys/class/gpio/gpio15 ] || INIT_PIN
|
||||
echo 0 > /sys/class/gpio/gpio15/value
|
||||
}
|
||||
|
||||
TOGGLE_SWITCH(){
|
||||
# initialise pin before doing anything
|
||||
[ -d /sys/class/gpio/gpio15 ] || INIT_PIN
|
||||
case $(cat /sys/class/gpio/gpio15/value) in
|
||||
1) SWITCH_OFF;;
|
||||
0) SWITCH_ON;;
|
||||
esac
|
||||
}
|
||||
|
||||
USAGE(){
|
||||
cat >&2 <<EOF
|
||||
Usage: pwr-switch <on|off|init|deinit>
|
||||
on: send on signal
|
||||
off: send off signal
|
||||
init: initialise pin
|
||||
deinit: deinitialise pin
|
||||
status: show pin initialisation state
|
||||
toggle: toggle on/off signal
|
||||
EOF
|
||||
}
|
||||
|
||||
case $1 in
|
||||
on) SWITCH_ON;;
|
||||
off) SWITCH_OFF;;
|
||||
init) INIT_PIN;;
|
||||
deinit) DEINIT_PIN;;
|
||||
status) PIN_STATUS;;
|
||||
toggle) TOGGLE_SWITCH;;
|
||||
*) USAGE;;
|
||||
esac
|
||||
```
|
||||
{{< end-details >}}
|
||||
|
||||
You could probably also do this in Python, but my knowledge of Python is nearly none.
|
||||
|
||||
# Remote interaction
|
||||
|
||||
You can probably make a guess as to how I set up the automation and interaction from other devices.
|
||||
That's right, I used an SSH forced command:
|
||||
```
|
||||
no-pty,command="/usr/local/sbin/pwr-switch toggle" ssh-ed25519 <contents of <lamp-key>.pub>
|
||||
```
|
||||
The unique thing here being that it needs to be executed as the root user in order to mess with the state of the pins.
|
||||
(Or at least in the case of my setup.)
|
||||
So having it be a forced command is a security benefit here as it prevents whatever device you're using to toggle your lamp from having to log in as the root user.
|
||||
All a device with the `<lamp-key>` can do, is toggle the state of `GPIO 15`.
|
||||
|
||||
You could contrivedly call this SIOT...
|
||||
|
||||
Since Android 12, there is the "Device controls" tile in the swipe-down-from-the-top-of-the-screen-menu.
|
||||
Termux can interact with the API that this system provides and allows you to add buttons corresponding to Termux' shortcuts.
|
||||
These shortcuts are executables found in `~/.shortcuts` within the Termux environment.
|
||||
Here I've created a little script that logs into my Raspberry Pi using the `<lamp-key>`, allowing me to toggle my lamp at the tap of a button as long as I'm on my home network.
|
||||
|
|
@ -1 +1 @@
|
|||
Subproject commit 830a4225322572492deef242a15f945b3f02d4e6
|
||||
Subproject commit 8122d5eb1ae06319cfc007454cd1ad46658aef1c
|
||||
Loading…
Reference in a new issue