利用python实现IP扫描

需求：写一个脚本，判断192.168.11.0/24网络里，当前在线ip有哪些？

知识点:

1 使用subprocess模块，来调用系统命令，执行ping 192.168.11.xxx 命令

2 调用系统命令执行ping命令的时候，会有返回值(ping的结果)，需要用到stdout=fnull, stderr=fnull方法，屏蔽系统执行命令的返回值

常规版本(代码)

import os
import time
import subprocess
def ping_call():
    start_time = time.time()
    fnull = open(os.devnull, 'w')
    for i in range(1, 256):
        ipaddr = 'ping 192.168.11.' + str(i)
        result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)
        current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())
        if result:
            print('时间:{} ip地址:{} ping fall'.format(current_time, ipaddr))
        else:
            print('时间:{} ip地址:{} ping ok'.format(current_time, ipaddr))
    print('程序耗时{:.2f}'.format(time.time() - start_time))
    fnull.close()
ping_call()

执行效果：

上面的执行速度非常慢，怎么能让程序执行速度快起来？

python提供了进程，线程，协程。分别用这三个对上面代码改进，提高执行效率，测试一波效率

进程池异步执行 – 开启20个进程

import os
import time
import subprocess
from multiprocessing import Pool
def ping_call(num):
    fnull = open(os.devnull, 'w')
    ipaddr = 'ping 192.168.11.' + str(num)
    result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)
    current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())
    if result:
        print('时间:{} ip地址:{} ping fall'.format(current_time, ipaddr))
    else:
        print('时间:{} ip地址:{} ping ok'.format(current_time, ipaddr))

    fnull.close()


if __name__ == '__main__':
    start_time = time.time()
    p = Pool(20)
    res_l = []
    for i in range(1, 256):
        res = p.apply_async(ping_call, args=(i,))
        res_l.append(res)
    for res in res_l:
        res.get()
    print('程序耗时{:.2f}'.format(time.time() - start_time))

执行结果：

线程池异步执行 – 开启20个线程

import os
import time
import subprocess
from concurrent.futures import ThreadPoolExecutor
def ping_call(num):
    fnull = open(os.devnull, 'w')
    ipaddr = 'ping 192.168.11.' + str(num)
    result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)
    current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())
    if result:
        print('时间:{} ip地址:{} ping fall'.format(current_time, ipaddr))
    else:
        print('时间:{} ip地址:{} ping ok'.format(current_time, ipaddr))
    fnull.close()

if __name__ == '__main__':
    start_time = time.time()
    thread_pool = ThreadPoolExecutor(20)
    ret_lst = []
    for i in range(1, 256):
        ret = thread_pool.submit(ping_call, i)
        ret_lst.append(ret)
    thread_pool.shutdown()
    for ret in ret_lst:
        ret.result()
    print('线程池(20)异步-->耗时{:.2f}'.format(time.time() - start_time))

执行结果：

协程执行—(执行多个任务，遇到I/O操作就切换)

使用gevent前，需要pip install gevent

from gevent import monkey;monkey.patch_all()
import gevent
import os
import time
import subprocess

def ping_call(num):
    fnull = open(os.devnull, 'w')
    ipaddr = 'ping 192.168.11.' + str(num)
    result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)
    current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())
    if result:
        print('时间:{} ip地址:{} ping fall'.format(current_time, ipaddr))
    else:
        print('时间:{} ip地址:{} ping ok'.format(current_time, ipaddr))
    fnull.close()

def asynchronous(): # 异步
    g_l = [gevent.spawn(ping_call, i) for i in range(1, 256)]
    gevent.joinall(g_l)

if __name__ == '__main__':
    start_time = time.time()
    asynchronous()
    print('协程执行-->耗时{:.2f}'.format(time.time() - start_time))

执行结果：

遇到I/O操作，协程的效率比进程，线程高很多!

总结：python中，涉及到I/O阻塞的程序中，使用协程的效率最高

最后附带协程池代码

gevent.pool

from gevent import monkey;monkey.patch_all()
import gevent
import os
import time
import subprocess
import gevent.pool

def ping_call(num):
    fnull = open(os.devnull, 'w')
    ipaddr = 'ping 192.168.11.' + str(num)
    result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)
    current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())
    if result:
        print('时间:{} ip地址:{} ping fall'.format(current_time, ipaddr))
    else:
        print('时间:{} ip地址:{} ping ok'.format(current_time, ipaddr))
    fnull.close()

if __name__ == '__main__':
    start_time = time.time()
    res_l = []
    p = gevent.pool.Pool(100)
    for i in range(1, 256):
        res_l.append(p.spawn(ping_call, i))
    gevent.joinall(res_l)
    print('协程池执行-->耗时{:.2f}'.format(time.time() - start_time))

执行结果: