mdnsd.service5

Usage

Overview

mdnsd needs at least one .service file to actively announce itself. The systems that mdnsd targets usually have an SSH or HTTP/HTTPS service, which can be located by end-users with mDNS-SD. E.g., mdnsd may be embedded in your printer, an access point, an industrial switch, or other headless network connected device.

Services are defined one per .service file and only two fields are mandatory:

type TYPE

The TYPE can be any service type from /etc/services, prefixed with an underscore. E.g., 'ipp' is port 631/tcp, which gives the type _ipp._tcp

port PORT

The port is the UDP or TCP port to announce. This can also be found in the file /etc/services.

There are also a few optional fields supported, see below for examples:

name STRING

Free form string to describe service. Usually what is presented to end users by discovery agents.

txt STRING

Text records are free-form strings that are included in service announcements. Useful for announcing meta data about your service.

target URL

URL to announce as canonical for this service.

cname URL

A cname is an alias that can be announced for unique service reqords. E.g., if only one HTTP service is available on the LAN it can be reached through the full name, or using the cname alias.

Examples

This section has some examples of mDNS service definitions.

# mDNS-SD advertisement of SSH service
type _ssh._tcp
port 22

# mDNS-SD advertisement of FTP service
name Troglobit FTP Server
type _ftp._tcp
port 21
txt server=uftpd
txt version=2.6
target ftp.luthien.local

# mDNS-SD advertisement of HTTP service
type _http._tcp
port 80
txt server=merecat
txt version=2.31
cname home.local

# mDNS-SD advertisement of foo._printer._tcp.local.
type _printer._tcp
port 515

# mDNS-SD advertisement of foo._ipp._tcp.local.
type _ipp._tcp
port 631

Files

/etc/services

List of standard service definitions in UNIX