Search for a free TCP port in python 3 (not completely safe, since between the check and the usage, there could be a race-condition)

search_free_port.py

#!/usr/bin/env python3
import socket

def search_free_port():
    port = 5000
    while True:
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
            if s.connect_ex(('localhost', port)) != 0:
                return port

        port += 1