Add nethsecurity_controller (#82)

index.rst

@@ -63,6 +63,7 @@ NethServer 8 administrator manual
    minio
    crowdsec
    imapsync
+   nethsecurity_controller
 
 .. toctree::
    :maxdepth: 2

nethsecurity_controller.rst

@@ -0,0 +1,21 @@
+=======================
+NethSecurity Controller
+=======================
+
+The NethSecurity controller allows for remote management of multiple `NethSecurity <https://docs.nethsecurity.org>`_ installations, referred to as units.
+
+The controller establishes a secure connection between the central server and the units.
+Each firewall registers with the server using the ns-plug client. Once registered, the server generates a VPN configuration 
+that enables secure communication between the controller and the unit.
+
+Key features of the NethSecurity controller include:
+
+- **Centralized Management**: Manage multiple firewalls from a single server.
+- **Secure Communication**: Establish a secure OpenVPN connection between the server and the firewalls.
+- **Easy Configuration**: Configure firewalls directly from the controller's user interface.
+- **Monitoring and Logging**: Collect and analyze logs from the firewalls using Loki for troubleshooting and monitoring purposes.
+- **Metrics Visualization**: Visualize metrics from the firewalls using the built-in Grafana dashboard. Metrics are collected using Prometheus.
+- **Web-based SSH**: Access the firewalls' command-line interface using a web-based SSH client.
+
+See the `NethSecurity controller documentation <https://docs.nethsecurity.org/en/latest/controller.html>`_ to learn more about the controller's features
+and how to set it up.