Avahi
Avahi is an implementation of Zeroconf and mDNS.
The project began with Lennart Poettering's implementation of mDNS and DNS-SD.
Contents
Installation
Most Linux distributions offer an avahi package. For BSD distributions, try avahi-daemon.
For systemd-capable systems, start and enable avahi-daemon.service.
The daemon binary is named avahi-daemon(8).
Configuration
networkd has a competing mDNS implementation that will need to be disabled before avahi can be made to work.
Alternatively, disable systemd-resolved.service entirely.
Name Resolution
For Avahi to insert domain name resolution for discovered services, an additional dependency (commonly named nss-mdns) is required.
Insert mdns_minimal [NOTFOUND=return] into /etc/nsswitch.conf, as below.
hosts: files mymachines myhostname mdns_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] dns
Firewalls
avahi-daemon(8) binds to port 5353. Firewalls such as ufw or awall must be reconfigured to open it.
Usage
Advertising Services
avahi-daemon(8) uses all /etc/avahi/services/*.service files that are readable by the avahi user and group. These take the form of structured XML. For example, an FTP service:
<?xml version="1.0" standalone='no'?>
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
<name>FTP</name>
<service>
<type>_ftp._tcp</type>
<port>21</port>
</service>
</service-group>
Discovery
In a terminal, use avahi-browse(1).
avahi-browse --all
Alternatively there is the graphical client avahi-discover(1).