Troubleshooting Tip: Viewing FortiNAC-F local RADIUS logs from GUI

1. From the Admin GUI, navigate to Network -> RADIUS.
2. From the 'Local Service' view, enable Debug & Troubleshooting. 

3. Enable logging options: 

• Service Log Level: Enables radiusd service to debug. Normal is recommended for most debugging. Select 'View logs' (Service log) to view debug output. 
• Service Debug Host MAC Filter (Optional): Scope service debug information to one or more (comma-separated) host MAC addresses. 
• FortiNAC Server Log Debug: Enable FortiNAC server debug related to Local RADIUS processing. This is useful when authentication requests successfully make it to the port-auth state. Select 'View Logs' (Server Log) to view the FortiNAC RADIUS debug output.
• Include Network Access Policy Debug: Lookup details to troubleshoot problems matching the proper Network Access Policy. For other post-auth issues. Leaving this option disabled is recommended for better readability. 

Note:

In later versions of FortiNAC, the debug level settings have been simplified and now only two options are available: Enabled or Disabled. Please remember to disable these debugs after each troubleshooting session, if the debugs are left running for a long time it may affect the health of the setup.

4. Select 'Submit' to enable debugging.
5. Select 'View Logs' to view the RADIUS logging enabled.
6. Disable the 'Enable logging' option once debugging is completed. For the best performance, disable the local RADIUS service debug once troubleshooting is complete. 
7. Select 'Submit'. 

Debugging output from both Service logs and Server Logs is also collected in a grab-log snapshot: Technical Tip: How to get a debug log report from FortiNAC-CA or FortiNAC-Manager. 

Related document: 

Configure FortiNAC RADIUS Server for Device Integration