Parallel tcp port scan

tcpscan.py

#!/usr/bin/env python3
# Scan TCP ports in a multithreaded fashion.

import multiprocessing
import re
import socket
import sys

def checkport(_):
	global queue
	host,port = queue.get()
	s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	s.settimeout(0.001 if host=='127.0.0.1' else 2)
	if s.connect_ex((host,port)) == 0:
		print('%s:%i open' % (host,port))
		hostport = (host,port)
	else:
		hostport = None
	s.close()
	print('%i    \r' % port, end='', file=sys.stderr)	# Show some progress.
	return hostport

def _clamp(minimum, x, maximum):
    return max(minimum, min(x, maximum))

def _initio(q, outp):
	global queue
	queue = q
	if not outp: sys.stdout.write = lambda x: x

def scan(host_ranges, outp=False):
	multiprocessing.freeze_support()
	q = multiprocessing.Queue()
	all_ports = []
	for host,loport,hiport in host_ranges:
		if outp:
			print('Scanning %s:%i-%i... ' % (host,loport,hiport))
		host = socket.gethostbyname(host)
		min_workers = _clamp(1, hiport-loport, 5)
		workers = _clamp(min_workers, (hiport-loport)//20, 80)	# Limit the number of threads.
		pool = multiprocessing.Pool(workers, _initio, [q, outp])
		[q.put((host,port)) for port in range(loport,hiport+1)]
		ports = pool.map(checkport, range(loport,hiport+1))
		del pool
		ports = list(filter(None, ports))
		if outp and not ports:
				print('No ports open on %s.' % host)
		all_ports += ports
	return all_ports

def parserange(host, default_host):
	dhost,dloport,dhiport = re.match(r'(.+):(\d+)-(\d+)', default_host).group(1,2,3)
	try: host,loport,hiport = re.match(r'(.+):(\d+)-(\d+)', host).group(1,2,3)
	except: loport,hiport = dloport,dhiport
	return host,int(loport),int(hiport)

if __name__ == '__main__':
	default = 'localhost:1-1024'
	host_ranges = [parserange(r, default) for r in sys.argv[1:]]
	scan(host_ranges, outp=True)