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Disconnecting Active RADIUS Users

Introduction

The RADIUS protocol uses UDP to communicate between the client and the server.
The client initiates all communication and the server simply replies.
There are however times when the need arise for the server to initiate communication to the client.
A typical example will be when there is a need to disconnect an active user.
Since January 2023 RADIUSdesk introduced an update that will allow you do send disconnect requests to RADIUS Clients in order to disconnect active users.

In order for the RADIUS server to communicate with the RADIUS Client we need determine two things.
- The type of client.
- The type of client in turn will determine how we will communicate with the RADIUS Client.
We currently support two types of clients.
- CoovaChilli (Used by MESHdesk and APdesk)
- Mikrotik
In the rest of the document we will discuss how the RADIUSdesk system communicate with these two types of clients.
We will also take a look where to make changes in order to add support for additional types of RADIUS Clients.

MESHdesk and APdesk automatically adds an associated RADIUS Client when adding a Captive Portal exit point.
This RADIUS Client will have the type of Coova-On-Meshdesk.

Disconnecting a user will then utilize the /var/www/rdcore/cake4/rd_cake/src/Controller/Component/KickerComponent.php component to contact the AP with instructions to disconnect the user.
When the MQTT mechanism is implemented disconnecting will be in real-time.
Without the MQTT mechanism disconnecting a user will take up to one minute.
The disconnect command used on CoovaChilli will be chilli_query logout mac <MAC Address>

With the Mikrotik RADIUS Clients we make use of the RouterOS API Client to communicate with the Mikrotik. (https://github.com/EvilFreelancer/routeros-api-php)
This is already included with RADIUSdesk.
Many times there will be a NAT connection between the Mikrotik and the RADIUSdesk server preventing the server to reach the Mikrotik directly.
Mikrotik fortunately supports a large amount of VPN technologies which you can choose from.
https://help.mikrotik.com/docs/display/ROS/Virtual+Private+Networks
If needed, please select one of your choosing. Setting them up is well documented in the Mikrotik documentation in the link above.
When adding a RADIUS Client and selecting the Mikrotik-API type you will be presented with a dialog to supply the detail for the API connection to the Mikrotik.
There is also a Test API Connection button which allows you to confirm that the API communication to the Mikrotik is indeed working.
In the screenshot above you can se part of the reply from the Mikrotik indicating that the communication via the API is established and good.