{"id":4639,"date":"2022-12-20T18:09:24","date_gmt":"2022-12-20T21:09:24","guid":{"rendered":"http:\/\/lode.uno\/linux-man\/index.php\/2022\/12\/20\/systemd-dnssd-man5\/"},"modified":"2022-12-20T18:09:24","modified_gmt":"2022-12-20T21:09:24","slug":"systemd-dnssd-man5","status":"publish","type":"post","link":"https:\/\/lode.uno\/linux-man\/2022\/12\/20\/systemd-dnssd-man5\/","title":{"rendered":"SYSTEMD.DNSSD (man5)"},"content":{"rendered":"

SYSTEMD.DNSSD<\/h1>\n

NAME<\/a>
SYNOPSIS<\/a>
DESCRIPTION<\/a>
[SERVICE] SECTION OPTIONS<\/a>
EXAMPLES<\/a>
SEE ALSO<\/a>
NOTES<\/a> <\/p>\n

\n

NAME <\/a> <\/h2>\n

systemd.dnssd \u2212 DNS\u2212SD configuration<\/p>\n

SYNOPSIS <\/a> <\/h2>\n

network_service<\/i>.dnssd<\/p>\n

DESCRIPTION <\/a> <\/h2>\n

DNS\u2212SD setup is performed by systemd-resolved<\/b>(8).<\/p>\n

The main network service file must have the extension .dnssd; other extensions are ignored.<\/p>\n

The .dnssd files are read from the files located in the system network directories \/usr\/lib\/systemd\/dnssd and \/usr\/local\/lib\/systemd\/dnssd, the volatile runtime network directory \/run\/systemd\/dnssd and the local administration network directory \/etc\/systemd\/dnssd. All configuration files are collectively sorted and processed in lexical order, regardless of the directories in which they live. However, files with identical filenames replace each other. Files in \/etc have the highest priority, files in \/run take precedence over files with the same name in \/usr\/lib. This can be used to override a system\u2212supplied configuration file with a local file if needed.<\/p>\n

Along with the network service file foo.dnssd, a “drop\u2212in” directory foo.dnssd.d\/ may exist. All files with the suffix “.conf” from this directory will be parsed after the file itself is parsed. This is useful to alter or add configuration settings, without having to modify the main configuration file. Each drop\u2212in file must have appropriate section headers.<\/p>\n

In addition to \/etc\/systemd\/dnssd, drop\u2212in “.d” directories can be placed in \/usr\/lib\/systemd\/dnssd or \/run\/systemd\/dnssd directories. Drop\u2212in files in \/etc take precedence over those in \/run which in turn take precedence over those in \/usr\/lib or \/usr\/local\/lib. Drop\u2212in files under any of these directories take precedence over the main network service file wherever located.<\/p>\n

[SERVICE] SECTION OPTIONS <\/a> <\/h2>\n

The network service file contains a [Service] section, which specifies a discoverable network service announced in a local network with Multicast DNS broadcasts.<\/p>\n

Name=<\/i><\/p>\n

An instance name of the network service as defined in the section 4.1.1 of RFC 6763<\/font><\/b> [1]<\/font><\/small> , e.g. “webserver”.<\/font><\/p>\n

The option supports simple specifier expansion. The following expansions are understood:<\/font><\/p>\n

Table\u00a01.\u00a0Specifiers available<\/b><\/font><\/p>\n

\"Image<\/b><\/font><\/p>\n

Type=<\/i><\/font><\/p>\n

A type of the network service as defined in the section 4.1.2 of<\/font> RFC 6763<\/font><\/b> [1]<\/font><\/small> , e.g. “_http._tcp”.<\/font><\/p>\n

Port=<\/i><\/font><\/p>\n

An IP port number of the network service.<\/font><\/p>\n

Priority=<\/i><\/font><\/p>\n

A priority number set in SRV resource records corresponding to the network service.<\/font><\/p>\n

Weight=<\/i><\/font><\/p>\n

A weight number set in SRV resource records corresponding to the network service.<\/font><\/p>\n

TxtText=<\/i><\/font><\/p>\n

A whitespace\u2212separated list of arbitrary key\/value pairs conveying additional information about the named service in the corresponding TXT resource record, e.g. “path=\/portal\/index.html”. Keys and values can contain C\u2212style escape sequences which get translated upon reading configuration files.<\/font><\/p>\n

This option together with TxtData=<\/i> may be specified more than once, in which case multiple TXT resource records will be created for the service. If the empty string is assigned to this option, the list is reset and all prior assignments will have no effect.<\/font><\/p>\n

TxtData=<\/i><\/font><\/p>\n

A whitespace\u2212separated list of arbitrary key\/value pairs conveying additional information about the named service in the corresponding TXT resource record where values are base64\u2212encoded string representing any binary data, e.g. “data=YW55IGJpbmFyeSBkYXRhCg==”. Keys can contain C\u2212style escape sequences which get translated upon reading configuration files.<\/font><\/p>\n

This option together with TxtText=<\/i> may be specified more than once, in which case multiple TXT resource records will be created for the service. If the empty string is assigned to this option, the list is reset and all prior assignments will have no effect.<\/font><\/p>\n

EXAMPLES <\/a> <\/h2>\n

Example\u00a01.\u00a0HTTP service<\/b><\/font><\/p>\n

# \/etc\/systemd\/dnssd\/http.dnssd
[Service]
Name=%H
Type=_http._tcp
Port=80
TxtText=path=\/stats\/index.html t=temperature_sensor<\/font><\/p>\n

This makes the http server running on the host discoverable in the local network given MulticastDNS is enabled on the network interface.<\/font><\/p>\n

Now the utility “resolvectl” should be able to resolve the service to the host’s name:<\/font><\/p>\n

$ resolvectl service meteo._http._tcp.local
meteo._http._tcp.local: meteo.local:80 [priority=0, weight=0]
169.254.208.106%senp0s21f0u2u4
fe80::213:3bff:fe49:8aa%senp0s21f0u2u4
path=\/stats\/index.html
t=temperature_sensor
(meteo\/_http._tcp\/local)<\/font><\/p>\n

\u2212\u2212 Information acquired via protocol mDNS\/IPv6 in 4.0ms.
\u2212\u2212 Data is authenticated: yes<\/font><\/p>\n

“Avahi” running on a different host in the same local network should see the service as well:<\/font><\/p>\n

$ avahi\u2212browse \u2212a \u2212r
+ enp3s0 IPv6 meteo Web Site local
+ enp3s0 IPv4 meteo Web Site local
= enp3s0 IPv6 meteo Web Site local
hostname = [meteo.local]
address = [fe80::213:3bff:fe49:8aa]
port = [80]
txt = [“path=\/stats\/index.html” “t=temperature_sensor”]
= enp3s0 IPv4 meteo Web Site local
hostname = [meteo.local]
address = [169.254.208.106]
port = [80]
txt = [“path=\/stats\/index.html” “t=temperature_sensor”]<\/font><\/p>\n

SEE ALSO <\/a> <\/h2>\n

systemd<\/b>(1), systemd-resolved.service<\/b>(8), resolvectl<\/b>(1)<\/font><\/p>\n

NOTES <\/a> <\/h2>\n\n\n
<\/td>\n\n

1.<\/font><\/p>\n<\/td>\n

<\/td>\n\n

RFC 6763<\/font><\/p>\n<\/td>\n

 <\/td>\n<\/tr>\n<\/table>\n

https:\/\/tools.ietf.org\/html\/rfc6763<\/font><\/p>\n

\n","protected":false},"excerpt":{"rendered":"

systemd.dnssd \u2212 DNS\u2212SD configuration <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[959],"tags":[961,1291,978],"class_list":["post-4639","post","type-post","status-publish","format-standard","hentry","category-5-formatos-de-ficheros","tag-961","tag-man5","tag-systemd"],"gutentor_comment":0,"_links":{"self":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts\/4639","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/comments?post=4639"}],"version-history":[{"count":0,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts\/4639\/revisions"}],"wp:attachment":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/media?parent=4639"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/categories?post=4639"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/tags?post=4639"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}