On my Mac, I'm having trouble with a UDP port (500) that is "already in use", but it doesn't have an associated process anymore.
sudo netstat -na | grep "udp4.*\.500\>"
udp4 0 0 192.168.50.181.500 *.* udp4 0 0 192.168.29.166.500 *.*
But lsof doesn't show a process on port 500 (ie "sudo lsof -i:500 -P" reports nothing).
Note that I am using "sudo" for these calls, so it should show all resources.
How can I figure out how to unbind the resource attached to port 500 so I can use it again?