python调用tcpdump抓包过滤的方法_Python

本文实例为大家分享了python调用tcpdump 抓包过滤的具体代码，供大家参考，具体内容如下

之前在linux用python脚本写一个抓包分析小工具，实在不想用什么libpcap、pypcap所以，简单来了个tcpdump加grep搞定。基本思路是分别起tcpdump和grep两个进程，进程直接通过pipe交换数据，简单代码如下：

									#! /usr/bin/python

									def tcpdump():

									 import subprocess, fcntl, os

									 # sudo tcpdump -i eth0 -n -s 0 -w - | grep -a -o -E "Host: .*|GET /.*"

									 cmd1 = ['tcpdump', '-i', 'eth0', '-n','-B', '4096','-s', '0', '-w', '-']

									 cmd2 = ['grep', '--line-buffered', '-a', '-o', '-E', 'Host: .*|GET /.*']

									 p1 = subprocess.Popen(cmd1, stdout=subprocess.PIPE)

									 p2 = subprocess.Popen(cmd2, stdout=subprocess.PIPE, stdin=p1.stdout)

									 flags = fcntl.fcntl(p2.stdout.fileno(), fcntl.F_GETFL)

									 fcntl.fcntl(p2.stdout.fileno(), fcntl.F_SETFL, (flags | os.O_NDELAY | os.O_NONBLOCK))

									 return p2

									def poll_tcpdump(proc):

									 #print 'poll_tcpdump....'

									 import select

									 txt = None

									 while True:

									 # wait 1/10 second 

									 readReady, _, _ = select.select([proc.stdout.fileno()], [], [], 0.1)

									 if not len(readReady):

									  break

									 try:

									  for line in iter(proc.stdout.readline, ""):

									  if txt is None:

									   txt = ''

									  txt += line

									 except IOError:

									  print 'data empty...'

									  pass

									 break

									 return txt

									proc = tcpdump()

									while True:

									 text = poll_tcpdump(proc)

									 if text:

									 print '>>>> ' + text