======================syn_scan_one_port=====================================
#!/usr/bin/python3.4
# -*- coding=utf-8 -*-
import sys
from io import StringIO
import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
import re
from scapy.all import *

def syn_scan_one_port(hostname,port):
    f_handler = StringIO()

	__console__=sys.stdout

	sys.stdout = f_handler

	result_raw = sr(IP(dst=hostname)/TCP(sport=RandShort(),dport=[port],flags="S"), verbose = False)

	result_raw[0][0][1].display()

	sys.stdout=__console__

	scan_raw = f_handler.getvalue()

	flag_result = re.findall('.*\s+(flags)\s*=\s*(.*).*', scan_raw)

	for flag in flag_result:
		if flag[1] == 'SA':
			#print('Host: ' + hostname + '  Port:' + str(port) + '  is Open!!!')
			os._exit(3)

if __name__ == '__main__':
	syn_scan_one_port('202.100.1.200',139)
======================scapy_syn_scan=====================================
#!/usr/bin/python3.4
# -*- coding=utf-8 -*-
import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
import re
import time
import multiprocessing
from syn_scan_one_port import syn_scan_one_port
from scapy.all import *
def scapy_syn_scan(host,port_low,port_high):
    processes = []
	ports = []
	port_l = int(port_low)
	port_h = int(port_high) + 1
	for port in range(port_l,port_h):
		syn_one = multiprocessing.Process(target=syn_scan_one_port, args=(host, port))
		#print('Started ' + str(port) + '  Scan!!!')
		syn_one.start()
		processes.append(syn_one)
		ports.append(port)

	#print(processes)
	#print(ports)
	port_no = 0
	time.sleep(3)
	for process in processes:
		if process.exitcode == 3:
			print('Host: ' + host + '  Port:' + str(ports[port_no]) + '  is Open!!!')
		else:
			process.terminate()
		port_no = port_no + 1

if __name__ == '__main__':
	host = input('请你输入扫描主机的IP地址: ')
	port_low = input('请你输入扫描端口的最低端口号: ')
	port_high = input('请你输入扫描端口的最高端口号: ')
	scapy_syn_scan(host,port_low,port_high)
	#scapy_syn_scan('202.100.1.200',135,140)
=====================扫描效果===================================================
[root@Fedora python]# ./scapy_syn_scan.py 
请你输入扫描主机的IP地址: 202.100.1.200
请你输入扫描端口的最低端口号: 100
请你输入扫描端口的最高端口号: 500
Host: 202.100.1.200  Port:135  is Open!!!
Host: 202.100.1.200  Port:139  is Open!!!
Host: 202.100.1.200  Port:445  is Open!!!