docs: added avahi documentation

avahi.rst

@@ -0,0 +1,40 @@
+.. _avahi-section:
+
+=======================
+Avahi (mDNS reflector)
+=======================
+
+Multicast DNS (mDNS) allows devices to discover services on a local network without a centralized DNS server, using multicast traffic within the ``.local`` domain.
+A typical use case is IoT network segmentation: when IoT devices live in a dedicated network, control devices like smartphones and PCs rely on mDNS for discovery.
+However, mDNS traffic does not cross network boundaries, so an mDNS reflector such as Avahi is required to bridge the gap and allow service discovery across network segments.
+
+On NethSecurity, the ``avahi-nodbus-daemon`` package is available in the official repositories but is not installed by default.
+
+.. note::
+   Starting from version 8.7.2, extra packages are automatically reinstalled after system upgrade.
+   For earlier versions and for additional information, refer to this documentation: :ref:`restore_extra_packages-section`.
+
+Installation
+============
+
+Install the package with::
+
+    opkg update
+    opkg install avahi-nodbus-daemon
+
+Configuration
+=============
+
+By default, the mDNS reflector functionality is disabled. To enable it:
+
+1. Edit the Avahi daemon configuration file: ::
+
+     vi /etc/avahi/avahi-daemon.conf
+
+2. Find the line ``enable-reflector=no`` and change it to ``enable-reflector=yes``
+
+3. Restart the Avahi daemon to apply the changes: ::
+
+     /etc/init.d/avahi-daemon restart
+
+After enabling the reflector, mDNS traffic will be reflected across network interfaces, allowing service discovery to work between different network segments.

index.rst

@@ -110,6 +110,7 @@ NethSecurity administrator manual
    :maxdepth: 2
    :caption: Advanced (CLI)
 
+   avahi
    ddns
    dns_over_http
    smtp