lsof port

C++
sudo lsof -i:<port_number>sudo ss -lptn 'sport = :80'lsof -i tcp:53 #Check what is listening on port 53
lsof -t -i tcp:53 #Return the process PID listening on port 53$ lsof -i :port
# ex. lsof -i :3000
Source

Also in C++: