python portscanner

import sys
import socket
import threading
import time

PORTSTATUS_OPEN = 1
PORTSTATUS_CLOSED = 0

class PortScan(threading.Thread):
	def __init__(self, host, port):
		threading.Thread.__init__(self)
		
		self.host = host
		self.port = port

		self.port_status = PORTSTATUS_CLOSED

	def run(self):

		# We have to use reliable data transfer (RDT) which exists in SOCK_STREAM (TCP)
		# so we can be notified if connection failed.
		s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	
		# The socket has 10 seconds to figure out if port is open or not.
		# Port is open if a connection could be established.
		s.settimeout(10)
		try:
			t = s.connect((self.host, self.port))
		except:
			pass
		else:
			self.port_status = PORTSTATUS_OPEN
			s.close()

host = "www.aftonbladet.se"
start_port  = 25
end_port = 5500
threads = []
max_thread_count = 300

for port in xrange(start_port, end_port + 1):

	# Never have more than 300 threads active at same time...
	while threading.activeCount() > max_thread_count:
		
		sys.stdout.write("Too many threads active. Waiting for threads to terminate... ")
	
		sys.stdout.flush()
		for t in threads:
			t.join()

		sys.stdout.write("[done]\n")
		sys.stdout.flush()
		
	
	portscan_thread = PortScan(host, port)
	threads.append(portscan_thread)

	try: 
	
		# thread.start() calls the run() method in PortScan instance
		portscan_thread.start()
	except:
		# Should not happen.... If this error occurs try lowering max_thread_count
		print "Unexpected thread error: start(). [port ", port, "]"
	
	# For every 1000th port we have processed, print the port number 
	# in order to overview progress
	if port % 1000 == 0:
		print port

# Make sure all threads have been terminated 
# (complete with checking port status)
for t in threads:
	t.join()

# Open a file in which we will write all open ports
# Let's also make the terminal happy by printing them
output = open("test", "w")
output.write("Host: " + str(host) + "\n")
for t in threads:
	if t.port_status == PORTSTATUS_OPEN:
		print "Port", t.port , " is open"
		output.write(str(t.port) + "\n")
output.close()