how to close open sockets in linux code example

Example 1: how to close sockets ubuntu

sudo netstat -ap | grep :<port_number> 
  
#The second line will contain the process id. e.g: 7838/python3 (7838 is the pid)
kill <pid>

Example 2: debian kill open port

fuser -k 3000/tcp 	//will kill that process.

Example 3: how to close port in linux

sudo ufw allow PORT