= Avahi =

'''Avahi''' is an implementation of Zeroconf and mDNS.

The project began with Lennart Poettering's implementation of mDNS and DNS-SD.

<<TableOfContents>>

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== Installation ==

Most [[Linux]] distributions offer an `avahi` package. For [[BSD]] distributions, try `avahi-daemon`.

For `systemd`-capable systems, [[Linux/Systemd|start and enable]] `avahi-daemon.service`.

The daemon binary is named `avahi-daemon(8)`.

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== Configuration ==

[[Linux/SystemdNetworkd|networkd]] has a competing mDNS implementation that will need to be disabled before `avahi` can be made to work.

Alternatively, [[Linux/Systemd|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|ufw]] or [[Awall|awall]] must be reconfigured to open it.

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== 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)`.

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== See also ==

[[https://man.archlinux.org/man/extra/avahi/avahi-daemon.8.en|avahi-daemon(8)]]

[[https://man.archlinux.org/man/extra/avahi/avahi-browse.1.en|avahi-browse(1)]]

[[https://man.archlinux.org/man/extra/avahi/avahi-discover.1.en|avahi-discover(1)]]



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