# Use tokens (/en/realtime-media/interactive-live-streaming/build/authenticate-users/use-tokens/linux-c)

> For AI agents: see the complete documentation index at [llms.txt](/llms.txt).

To protect your business, it is best practice to authenticate every client that joins a channel. This guide explains how to fetch an authentication token from your token server, use it to join a channel, and renew the token when it expires.

## Understand the tech [#understand-the-tech]

      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
    When a user attempts to connect to an Agora channel, your app retrieves a token from the token server in your security infrastructure. Your app then sends this token to Agora SDRTN® for authentication. Agora SDRTN® reads the information stored in the token to validate the request.

    The following figure shows the call flow you implement to create step-up-authentication with Agora Interactive Live Streaming:

    **Token authentication flow**

    ![token authentication flow](https://assets-docs.agora.io/images/video-sdk/token-authentication.svg)

    ## Prerequisites [#prerequisites-14]

    Before starting, ensure that you have:

    * Implemented the [Quickstart](../../index.mdx) in your project.

    * Deployed a token server using either of the following guides:

      * [Deploy a token server](deploy-token-server.mdx)
      * [Deploy a middleware server](middleware-token-server.md)

    ## Implement basic authentication [#implement-basic-authentication-14]

    This section shows you how to implement basic authentication by acquiring a token and using it to join a channel.

    <CalloutContainer type="info">
      <CalloutDescription>
        The user ID and channel name used to join a channel must be consistent with the values used to generate the token.
      </CalloutDescription>
    </CalloutContainer>

    ## Reference [#reference-14]

    This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.

    ### API reference [#api-reference-8]

    * [agora\_rtc\_renew\_token](https://api-ref.agora.io/en/iot-sdk/linux/1.x/agora__rtc__api_8h.html#a87c94a2d518278926807e24592b41336)

    * [on\_token\_privilege\_will\_expire](https://api-ref.agora.io/en/iot-sdk/linux/1.x/structagora__rtc__event__handler__t.html#aef1aa16dd5b32baa1aa03887f40f6ee9)