Create an mqtt-dasher service. (Debian/Ubuntu distros).
- mqtt-dasher
- https://github.com/stjohnjohnson/mqtt-dasher
Limits permissions for promiscuous net socket access via libpcap.
This assumes npm install without the global flag so uses /opt/node_modules instead of /usr/lib.
Install
# install nodejs from debsource
curl -sL https://deb.nodesource.com/setup_5.x | sudo -E bash -
sudo apt-get install -y nodejs
# install mqtt-dasher and libpcap dependency
sudo apt-get install libpcap-dev
sudo npm install mqtt-dasher
# add user to run the service, and group to limit access to setcap files
sudo useradd mqtt-dasher -d /opt/node_modules/mqtt-dasher -U
# make a copy of nodejs to set privileged net capabilities on
sudo cp `which nodejs` /opt/node_modules/mqtt-dasher/nodejs.setcap
# set user and group for mqtt-dasher first
sudo chgrp mqtt-dasher /opt/node_modules/mqtt-dasher/nodejs.setcap
sudo chmod 750 /opt/node_modules/mqtt-dasher/nodejs.setcap
# allow raw sockets and net admin for promiscuous mode
sudo setcap 'CAP_NET_RAW+eip CAP_NET_ADMIN+eip' /opt/node_modules/mqtt-dasher/nodejs.setcap
Create the Service
/etc/systemd/system/mqtt-dasher.service
[Unit]
Description=mqtt-dasher service
[Service]
ExecStart=/opt/node_modules/mqtt-dasher/nodejs.setcap /opt/node_modules/mqtt-dasher/server.js
# WorkingDirectory=/opt/node_modules/mqtt-dasher # Required on some systems
Restart=always
RestartSec=10 # Restart service after 10 seconds if node service crashes
StandardOutput=syslog # Output to syslog
StandardError=syslog # Output to syslog
SyslogIdentifier=mqtt-dasher
User=mqtt-dasher
Group=mqtt-dasher
Environment=CONFIG_DIR=/etc/mqtt-dasher NODE_ENV=production
[Install]
WantedBy=multi-user.target
Configure and start
sudo mkdir /etc/mqtt-dasher
/etc/mqtt-dasher/config.yml
mqtt:
host: localhost
## Preface for the topics $PREFACE/$TOPIC
## (not in mqtt-dasher 0.1.0)
#preface: ha/dash
buttons:
ab:cd:ef:12:34:56: ha/dash/listerine
sudo systemctl enable mqtt-dasher
sudo systemctl start mqtt-dasher
Home Assistant Switch
An mqtt switch which:
- turns on when the dash button is activated
- turns off when the dash button deactivates
- can be activated and deactivated from HA
switch:
- name: Listerine
platform: mqtt
command_topic: ha/dash/listerine
state_topic: ha/dash/listerine
payload_on: 'active'
payload_off: 'inactive'
retain: false
The switch isn't intended to be used in the HA UI, it should be mapped to a script instead.
To Do
Compile mqtt-dasher with nexe so that nodejs.setcap can't be so easily abused.