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--- docs:guide-developer:mdns [2021/05/04 21:49] – /etc/umdns stokito
+++ docs:guide-developer:mdns [2024/10/17 00:59] (current) – [Config File] bartprokop
@@ Line 5: / Line 5: @@
 //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]].
 ==== 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 ====
 <code - /etc/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>
 Note that it may be unsafe to enable umdns on ''wan'' interface.
+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>
+config rule
+        option src_port '5353'
+        option src '*'
+        option name 'Allow-mDNS'
+        option target 'ACCEPT'
+        option dest_ip '224.0.0.251'
+        option dest_port '5353'
+        option proto 'udp'
+</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]]
 ==== Browsing announced services ====
@@ Line 80: / Line 97: @@
 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>
-# 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" ] } }
 </code>
@@ Line 105: / Line 122: @@
 If you wish to create a more complicated mdns information block, see ''procd_add_mdns_service'' in ''/lib/functions/procd.sh'' but be warned that umdns probably can't automatically support everything you can represent in json.
-Alternatively you can create a service description in JSON file and put it into ''/etc/umdns/'' folder:
+===== Service description files in /etc/umdns =====
+umdns advertises the services whose ''*.json'' files are found in ''/etc/umdns''. This is similar to how Avahi advertises ''*.service'' files in ''/etc/avahi/services/''.
+For example the same WebDAV service description:
 <code - /etc/umdns/nextcloud_webdav.json>
 {
@@ Line 118: / Line 138: @@
 }
 </code>
-See examples in [[commit>?p=project/mdnsd.git;a=tree;f=json;hb=HEAD|umdns sources]]
+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"
+    ]
+  }
+}
+</code>
+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 ===
+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''.