How to check if a network port is open?

You can using the socket module to simply check if a port is open or not.

It would look something like this.

import socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
result = sock.connect_ex(('127.0.0.1',80))
if result == 0:
   print "Port is open"
else:
   print "Port is not open"
sock.close()

If you want to use this in a more general context, you should make sure, that the socket that you open also gets closed. So the check should be more like this:

import socket
from contextlib import closing
   
def check_socket(host, port):
    with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
        if sock.connect_ex((host, port)) == 0:
            print("Port is open")
        else:
            print("Port is not open")