How to catch unauthorized requests to the server

I am using the Traccar server to log all my GPS device positions. How would I catch the GPS devices thats are not in my Identity List? Meaning I change the ip and port on the device but i do not add them as a user on the server.

For unknown devices you will see warnings in the log file (tracker-server.log).

thank you Anton

From a previous post here, let me share one more way of filtering out data from the log

if you are using php you can use the following in your php script to view unknown devices from last 1000 records in the log

echo shell_exec('tail -1000 /opt/traccar/logs/tracker-server.log | grep "Unknown device"');