feat: added DNSMasq documentation (#84)

Co-authored-by: Davide Principi <davide.principi@nethesis.it>

dnsmasq.rst

@@ -0,0 +1,85 @@
+.. _dnsmasq-section:
+
+=======
+DNSMasq
+=======
+
+The DNSMasq module is a lightweight DNS and DHCP server designed to provide its services within a private network. It is not recommended for use as a public DNS server.
+
+It can be installed through the :ref:`software_center-section`.
+
+
+Prerequisites
+=============
+
+The only prerequisite is a network interface configured. This means that the network should have a valid IPv4 address and a valid subnet mask.
+Please refer to your distro documentation on how to properly configure a network interface.
+
+
+Configuration
+=============
+
+After installing the module, you can configure both the DNS and DHCP server through the web interface.
+
+Select in the ``Interface`` field the interface that you want to use for DNS and DHCP server, then press :guilabel:`Save`.
+
+Once the configuration is saved, there will be available two toggle switches to enable/disable DNS and DHCP server.
+
+
+DHCP
+====
+
+The DHCP server can be configured with the following options:
+
+- ``IP range start``: The first IP address that will be assigned to clients.
+- ``IP range end``: The last IP address that will be assigned to clients.
+- ``Lease time``: The time that the IP address will be assigned to the client, expressed in hours.
+
+The fields are automatically filled with default values at the first configuration, but you can change them according to your needs. Additional options can be configured manually, please refer to `Advanced Configuration`_ section.
+
+DNS
+===
+
+The DNS server can be configured with the following options:
+
+- ``Primary forwarding server``: The primary DNS server that will be used to resolve the queries.
+- ``Secondary forwarding server``: The secondary DNS server that will be used to resolve the queries.
+
+When the DNS server is enabled, all Fully Qualified Domain Names (FQDNs) configured within the node will be resolved using a 'CNAME' record pointing to the node's hostname.
+
+.. note::
+    The DNS server will not automatically resolve the entries in the ``/etc/hosts`` file. To resolve the entries in the ``/etc/hosts`` file, you need to add them manually in the `DNS Records`_ section.
+
+
+DNS Records
+===========
+
+Additional DNS entries can be added in the ``DNS Records`` section. Simply press the :guilabel:`Add DNS Record` button and fill the fields with the desired values:
+
+- ``Hostname``: The hostname that will be resolved.
+- ``IP Address``: The IP address that will be resolved to the hostname.
+
+IP addresses can be either IPv4 or IPv6.
+
+
+Advanced Configuration
+======================
+
+The module provides additional configuration options that can be accessed manually through the configuration files.
+
+The directories that accept custom files are located in the root directory of the module, under the `state` directory.
+
+The following directories can be used to add custom configuration files:
+
+- ``dnsmasq.d``: This directory is used to add custom configuration files for the DNSMasq service.
+  The files must have the `.conf` extension.
+  Please refer to the `DNSMasq documentation <https://dnsmasq.org/docs/dnsmasq-man.html>`_ for more information on how to configure the service.
+- ``dnsmasq_hosts.d``: This directory is used to add custom hosts files that will be used by the DNSMasq service. 
+  The format of the file is the same as the `/etc/hosts` file.
+  Refer to the `manual <https://man7.org/linux/man-pages/man5/hosts.5.html>`_ for more information on how to write the file.
+
+After adding the custom files, you need to restart the service to apply the changes.
+
+The custom files enrich the existing configuration. You can customize the provided DHCP instance without creating a custom one using the tag `default`, more info can be found in the `DNSMasq documentation <https://dnsmasq.org/docs/dnsmasq-man.html>`_.
+
+The custom files are included in the module backup.

index.rst

@@ -64,6 +64,7 @@ NethServer 8 administrator manual
    crowdsec
    imapsync
    nethsecurity_controller
+   dnsmasq
 
 .. toctree::
    :maxdepth: 2