mDNS on Raspberry Pi

Setting up mDNS (ZeroConf)

If you have a single Raspberry Pi (rPi) on your network, you can connect to it via its IP address (192.168.1.128 for example) or via a local DNS name of raspberrypi.local

  
  ssh pi@192.168.1.128
  
  ssh pi@raspberrypi.local

If you have multiple rPi on the network, you can either have to remember several IP addresses, or you can use the magic of mDNS (part of a suite of network technologies called ZeroConf) to give them all useful, memorable names. You’ll need to set the wanted name of the Pi in two files (the content of my files are shown), basically replace any occurrence of ‘raspberrypi’ with the name you want. I’m using weather here, because this rPi will be used to collect and store weather sensor data.

1. /etc/hostname

  
  pi@weather:~ $ cat /etc/hostname



weather

2. /etc/hosts

  
  pi@weather:~ $ cat /etc/hosts



127.0.0.1       localhost
::1             localhost ip6-localhost ip6-loopback
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters

127.0.1.1       weather

The names can’t include spaces, odd characters or fullstops.

When you’ve got the files set correctly, you need to check if you have the mDNS server installed

  
  pi@weather:~ $ dpkg -l |grep avahi



ii  avahi-daemon                         0.8-5+deb11u1                    arm64        Avahi mDNS/DNS-SD daemon
ii  libavahi-client3:arm64               0.8-5+deb11u1                    arm64        Avahi client library
ii  libavahi-common-data:arm64           0.8-5+deb11u1                    arm64        Avahi common data files
ii  libavahi-common3:arm64               0.8-5+deb11u1                    arm64        Avahi common library
ii  libavahi-core7:arm64                 0.8-5+deb11u1                    arm64        Avahi's embeddable mDNS/DNS-SD library
ii  libavahi-glib1:arm64                 0.8-5+deb11u1                    arm64        Avahi GLib integration library

If you see something like the above, then you’ve got the software installed. If you see nothing printed out, then you can install the software with

  
  pi@weather:~ $ sudo apt install avahi-daemon

Either way, once you’ve got the software installed, you can start it with

  
  pi@weather:~ $ sudo systemctl status avahi-daemon.service



Loaded: loaded (/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled)
     Active: active (running)

It’s probably a good idea to reboot the rPi at this point, it should work without a reboot, but starting from a clean slate is a good idea.

Once the rPi has booted, you should be able to access it on the network as (in my case)

  
  ssh pi@weather.local