Problem: What does *:* mean in netstat -an example: UDP 0.0.0.0:12345 *:*
What does *:* mean in netstat -an example: UDP 0.0.0.0:12345 *:*
Solution: What does *:* mean in netstat -an example: UDP 0.0.0.0:12345 *:*
It denotes the TCP or UDP port of the connection.
In your example, it would mean that some program listens on all your interfaces for incoming UDP connections on port 12345