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docs:guide-developer:mdns [2021/05/04 22:15] – stokitodocs:guide-developer:mdns [2024/10/17 00:59] (current) – [Config File] bartprokop
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 //This is early stage documentation, but at least attempts to cover some basic usage, and bring umdns usage out of the dark.// //This is early stage documentation, but at least attempts to cover some basic usage, and bring umdns usage out of the dark.//
  
-mDNS, also known as Bonjour or zero-configuration networking, enables automatic discovery of computers, devices, and services on IP networks. It is an internet standard documented in [[https://tools.ietf.org/html/rfc6762|RFC6762]].+mDNS, also known as Bonjour or zero-configuration networking (ZeroConf) or DNS Service Discovery (DNS-SD), enables automatic discovery of computers, devices, and services on IP networks. It is an internet standard documented in [[https://tools.ietf.org/html/rfc6762|RFC6762]].
  
 The [[packages:pkgdata:umdns]] package provides a compact implementation of this standard, well integrated with the OpenWrt system environment. In particular, almost all interaction with the daemon is via [[docs:guide-developer:ubus]]. The [[packages:pkgdata:umdns]] package provides a compact implementation of this standard, well integrated with the OpenWrt system environment. In particular, almost all interaction with the daemon is via [[docs:guide-developer:ubus]].
  
 ==== Alternatives ==== ==== Alternatives ====
- +See [[docs:guide-user:network:zeroconfig:zeroconf|Zero configuration networking in OpenWrt]]
-  * mdnsd - provided by Apple's mDNSResponder package +
-  * [[https://wiki.archlinux.org/title/avahi|avahi]] - A fairly full, but quite large implementation +
 ==== Config File ==== ==== Config File ====
  
 <code - /etc/config/umdns> <code - /etc/config/umdns>
 config umdns config umdns
-        option jail 1 + option jail 1 # enables jail - see procd 
-        list network lan + list network lan 
-        list network dmz # Provides visibility into both networks, but does not act as a repeater+ list network dmz # Provides visibility into both networks, but does not act as a repeater
 </code> </code>
 +
 Note that it may be unsafe to enable umdns on ''wan'' interface. Note that it may be unsafe to enable umdns on ''wan'' interface.
  
-Unsure that you open UDP port 5353 is opened in firewall:+Note that ''%%network list%%'' argument refers to interface name under ''%%/etc/config/network%%'' not the device name shown by ''%%ifconfig%%''. Test if you using the right name with ''%%ifstatus%%''. So if you have something like ''%%config interface 'vlan1'%%'' in your ''%%/etc/config/network%%'', use ''%%vlan1%%''. 
 + 
 +==== Install ==== 
 +umdns is available starting from OpenWRT 17 and to install it execute ''opkg install umdns'' 
 + 
 +==== Firewall ==== 
 +If you need to advertise on WAN or other networks then UDP port 5353 should be opened in firewall:
 <code - /etc/config/firewall> <code - /etc/config/firewall>
 config rule config rule
         option src_port '5353'         option src_port '5353'
         option src '*'         option src '*'
-        option name 'zeroconf-5353'+        option name 'Allow-mDNS'
         option target 'ACCEPT'         option target 'ACCEPT'
-        list dest_ip '224.0.0.251'+        option dest_ip '224.0.0.251'
         option dest_port '5353'         option dest_port '5353'
-        list proto 'udp'+        option proto 'udp'
 </code> </code>
 To configure from GUI see "Firewall rules" section of [[https://blog.christophersmart.com/2020/03/30/resolving-mdns-across-vlans-with-avahi-on-openwrt/|Resolving mDNS across VLANs with Avahi on OpenWRT]] To configure from GUI see "Firewall rules" section of [[https://blog.christophersmart.com/2020/03/30/resolving-mdns-across-vlans-with-avahi-on-openwrt/|Resolving mDNS across VLANs with Avahi on OpenWRT]]
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 The umdns scans all the services listed in ubus (''ubus call service list'') and looks for ''mdns'' objects in their data object. You can view this more selectively for example with: The umdns scans all the services listed in ubus (''ubus call service list'') and looks for ''mdns'' objects in their data object. You can view this more selectively for example with:
 <code> <code>
-# ubus call service list | jsonfilter -e '@[*].instances[*].data.mdns'+# ubus call service list | jsonfilter -e "$[*]['instances'][*]['data']['mdns']"
 { "ssh_22": { "service": "_ssh._tcp.local", "port": 22, "txt": [ "daemon=dropbear" ] } } { "ssh_22": { "service": "_ssh._tcp.local", "port": 22, "txt": [ "daemon=dropbear" ] } }
 </code> </code>
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       "path=/nextcloud/remote.php/dav/files/YOUR_USER/",       "path=/nextcloud/remote.php/dav/files/YOUR_USER/",
       "u=YOUR_USER"       "u=YOUR_USER"
 +    ]
 +  }
 +}
 +</code>
 +Or you can advertise SFTP and SSH:
 +<code - /etc/umdns/ssh.json>
 +{
 +  "ssh_login": {
 +    "service": "_ssh._tcp.local",
 +    "port": 22,
 +    "txt": [
 +      "u=root"
 +    ]
 +  },
 +  "sftp_share": {
 +    "service": "_sftp-ssh._tcp.local",
 +    "port": 22,
 +    "txt": [
 +      "path=/",
 +      "u=root"
     ]     ]
   }   }
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 </code> </code>
 See more examples in [[commit>?p=project/mdnsd.git;a=tree;f=json;hb=HEAD|umdns sources]] See more examples in [[commit>?p=project/mdnsd.git;a=tree;f=json;hb=HEAD|umdns sources]]
 +
 +The reload the umdns service with: ''ubus call umdns reload'' or ''service umdns reload''
  
 ==== Testing === ==== Testing ===
-To see that service was advertised you may use ''avahi-discover'' or ''avahi-browse -d local _webdav._tcp.local''+To see that service was advertised you may use ''avahi-discover'' GUI application. 
 +To see from a command line use ''avahi-browse --all''. 
 +To find a specific service use: ''avahi-browse -d local _webdav._tcp''. 
 + 
  • Last modified: 2021/05/04 22:15
  • by stokito