TCP Scanner with async generators

async_gen_scanner.py

import time
import asyncio

timeout = 1.0

async def check_ports(host: str, start: int, end: int, max=10):
    found = 0
    for port in range(start, end):
        try:
            future = asyncio.open_connection(host=host, port=port)
            r, w = await asyncio.wait_for(future, timeout=timeout)
            yield port
            found += 1
            w.close()
            if found >= max:
                return
        except asyncio.TimeoutError:
            pass # closed

async def scan(start, end, host):
    results = []
    async for port in check_ports(host, start, end, max=1):
        results.append(port)
    return results

if __name__ == '__main__':
    start = time.time()
    host = "something-you-own.com"
    scan_range = 80, 100
    results = asyncio.run(scan(*scan_range, host))
    for result in results:
        print("Port {0} is open".format(result))
    print("Completed scan in {0} seconds".format(time.time() - start))