[python]multi thread tcp connect port scanner

#!/usr/bin/python
import optparse
from socket import *
from threading import *
screenLock = Semaphore(value=1)
def connScan(host,port):
    try:
        s = socket(AF_INET,SOCK_STREAM)
        s.connect((host,port))
        screenLock.acquire()
        print '[+] '+str(port)+' open'
    except:
        screenLock.acquire()
        print '[-] '+str(port)+' close'
    finally:
        screenLock.release()
        s.close()
def portScan(host,ports):
    try:
        ip = gethostbyname(host)
    except:
        print "[-] Cannot resolve '%s':  Unknown host "%host
        return
    try:
        host = gethostbyaddr(ip)[0]
        print '[+] results for host '+host
    except:
        print '[+] results for ip '+ip
    setdefaulttimeout(1)
    for port in ports:
        t = Thread(target=connScan,args=(ip,int(port)))
        t.start()
def main():
    parser = optparse.OptionParser('usage %prog -H <target host> -p <target port>')
    parser.add_option('-H',dest='host',type='string',help='specify target host')
    parser.add_option('-p',dest='ports',type='string',help='specify target port[s] by comma')
    (options,args) = parser.parse_args()
    host = options.host
    ports = str(options.ports)
    if (host == None) | (ports == None):
        print parser.usage
        exit(0)
    ports = ports.split(",")
    portScan(host,ports)
if __name__ == "__main__":
    main()