radtest

radtest is a command-line utility that comes with FreeRADIUS. It is used to test RADIUS authentication by sending Access-Request packets to a RADIUS server and displaying the server's response. This tool is invaluable for administrators when they need to verify the functionality and configuration of their RADIUS server setup.

Key Features of radtest

  • Simplicity: Provides an easy way to test RADIUS authentication.

  • Diagnostic Tool: Useful for troubleshooting and verifying RADIUS server configurations.

  • Command-Line Based: Can be easily scripted for automated testing.

Installation

radtest is included with the FreeRADIUS client utilities package. To install it, you need to install the FreeRADIUS client utilities.

On Debian-based systems:

sudo apt-get install freeradius-utils

On Red Hat-based systems:

sudo yum install freeradius-utils

Basic Usage

The basic syntax for radtest is as follows:

radtest [options] <username> <password> <radius-server> <nas-port> <secret> [nas-ip-address]

  • <username>: The username you want to authenticate.

  • <password>: The password for the user.

  • <radius-server>: The IP address or hostname of the RADIUS server.

  • <nas-port>: The NAS port number. Typically set to 0 for testing.

  • <secret>: The shared secret between the NAS and the RADIUS server.

  • [nas-ip-address]: (Optional) The IP address of the NAS.

Example Commands

Basic Authentication Test

To test authentication for user alice with password password123 against a RADIUS server at localhost with shared secret testing123:

radtest alice password123 localhost 0 testing123

Specifying NAS IP Address

To specify the NAS IP address as 192.168.1.1:

radtest alice password123 localhost 0 testing123 192.168.1.1

Detailed Example

Consider you have a RADIUS server running on 192.168.1.100 with the shared secret radiusSecret. You want to test the authentication for user bob with the password bobPassword.

  1. Open your terminal.

  2. Execute the radtest command as follows:

    radtest bob bobPassword 192.168.1.100 0 radiusSecret

Interpreting the Output

The radtest command will provide output that helps you understand the RADIUS server's response. Here’s an example output:

Sending Access-Request of id 45 to 192.168.1.100 port 1812
        User-Name = "bob"
        User-Password = "bobPassword"
        NAS-IP-Address = 127.0.1.1
        NAS-Port = 0
        Message-Authenticator = 0x00
        Cleartext-Password = "bobPassword"
Received Access-Accept Id 45 from 192.168.1.100:1812 to 0.0.0.0:0 length 20

  • Access-Request: Indicates that an authentication request was sent to the RADIUS server.

  • Access-Accept: Indicates that the RADIUS server accepted the authentication request, meaning the credentials were correct.

If the authentication fails, you might see Access-Reject instead of Access-Accept.

Troubleshooting Tips

  • Shared Secret Mismatch: Ensure that the shared secret specified in the radtest command matches the one configured on the RADIUS server.

  • User Credentials: Verify that the username and password are correct and exist in the RADIUS server's user database.

  • Network Issues: Ensure that the RADIUS server is reachable from the client machine and there are no firewall rules blocking the communication on port 1812.

  • RADIUS Server Logs: Check the logs on the RADIUS server for any error messages or additional details about the failed authentication attempt.

Conclusion

radtest is a powerful and straightforward tool for testing and verifying RADIUS authentication setups. It helps administrators diagnose and resolve configuration issues, ensuring that the RADIUS server is functioning correctly. By understanding how to use radtest and interpret its output, administrators can efficiently manage and troubleshoot their RADIUS environments.

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