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用Python編寫一個高效的端口掃描器的方法

 更新時間：2018年12月20日 09:34:14   作者：耀凱考前突擊大師  
這篇文章主要介紹了用Python編寫一個高效的端口掃描器的方法，小編覺得挺不錯的，現(xiàn)在分享給大家，也給大家做個參考。一起跟隨小編過來看看吧

PyPortScanner

python多線程端口掃描器。

輸出示例：

Github

此端口掃描器的源碼，文檔及詳細(xì)調(diào)用方法見Github PythonPortScanner by Yaokai。

背景

有時候，在進(jìn)行網(wǎng)絡(luò)相關(guān)的研究的時候，我們需要執(zhí)行一些有目的的參數(shù)測量。而端口掃描就是其中比較普遍也比較重要的一項。所謂的端口掃描，就是指通過TCP握手或者別的方式來判別一個給定主機(jī)上的某些端口是否處理開放，或者說監(jiān)聽的狀態(tài)?，F(xiàn)有的使用比較廣泛的端口掃描工具是nmap。毋庸置疑，nmap是一款非常強(qiáng)大且易于使用的軟件。但nmap是一款運(yùn)行于terminal中的軟件，有時在別的代碼中調(diào)用并不是很方便，甚至沒有相應(yīng)的庫。另外，nmap依賴的其他庫較多，在較老的系統(tǒng)中可能無法使用較新的nmap，這樣會造成掃描的不便。另外，nmap在掃描時需要root權(quán)限。基于這個原因，我用python2.7自帶的庫開發(fā)了一款高效的多線程端口掃描器來滿足使用需要。

具體實現(xiàn)

I. 利用TCP握手連接掃描一個給定的(ip,port)地址對

為了實現(xiàn)端口掃描，我們首先明白如何使用python socket與給定的(ip, port)進(jìn)行TCP握手。為了完成TCP握手，我們需要先初始化一個TCP socket。在python中新建一個TCP socket的代碼如下：

TCP_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #(1)
TCP_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1) #(2)
TCP_sock.settimeout(delay) #(3)

其中(1)是初始化socket的代碼，socket.AF_INTE參數(shù)表示IPv4 socket，socket.SOCK_STREAM參數(shù)表示TCP socket。這樣我們就初始化了一個使用IPv4，TCP協(xié)議的socket。

(2)使用了socket.setsockopt()來設(shè)置socket的另一些參數(shù)。socket.SOL_SOCKET指定當(dāng)前socket將使用setsockopt()中后面的參數(shù)。socket.SO_REUSEPORT表明當(dāng)前socket使用了可復(fù)用端口的設(shè)置。socket.SO_REUSEPORT具體含義可以參考我的另一篇文章。

(3)將socket的連接超時時間設(shè)置為delay變量所對應(yīng)的時間（以秒為單位）。這么做是為了防止我們在一個連接上等待太久。
了解了如何新建一個socket，我們就可以開始對給定的(ip,port)對進(jìn)行TCP連接。代碼如下：

try:
  result = TCP_sock.connect_ex((ip, int(port_number)))

  # If the TCP handshake is successful, the port is OPEN. Otherwise it is CLOSE
  if result == 0:
    output[port_number] = 'OPEN'
  else:
    output[port_number] = 'CLOSE'

    TCP_sock.close()

except socket.error as e:
  output[port_number] = 'CLOSE'
  pass

因為這是一個I/O操作，為了處理可能出現(xiàn)的異常，我們需要在try,except塊處理這部分操作。其次，我們根據(jù)socket.connect_ex()方法連接目標(biāo)地址，通過該方法返回的狀態(tài)代碼來判斷連接是否成功。該方法返回0代表連接成功。所以當(dāng)返回值為0的時候?qū)?dāng)前端口記錄為打開狀態(tài)。反之記錄為關(guān)閉。另外，當(dāng)連接操作出現(xiàn)異常的時候，我們也將端口記錄為關(guān)閉狀態(tài)，因為其并不能被成功連接（可能因為防火墻或者數(shù)據(jù)包被過濾等原因）。

需要注意的是，在連接完成后我們一定要調(diào)用socket.close()方法來關(guān)閉與遠(yuǎn)程端口之間的TCP連接。否則的話我們的掃描操作可能會引起所謂的TCP連接懸掛問題（Hanging TCP connection）。

總結(jié)起來，TCP握手掃描的整體代碼如下：

"""
Perform status checking for a given port on a given ip address using TCP handshake

Keyword arguments:
ip -- the ip address that is being scanned
port_number -- the port that is going to be checked
delay -- the time in seconds that a TCP socket waits until timeout
output -- a dict() that stores result pairs in {port, status} style (status = 'OPEN' or 'CLOSE')
"""
def __TCP_connect(ip, port_number, delay, output):
  # Initilize the TCP socket object
  TCP_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  TCP_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
  TCP_sock.settimeout(delay)

  try:
    result = TCP_sock.connect_ex((ip, int(port_number)))

    # If the TCP handshake is successful, the port is OPEN. Otherwise it is CLOSE
    if result == 0:
      output[port_number] = 'OPEN'
    else:
      output[port_number] = 'CLOSE'

    TCP_sock.close()

  except socket.error as e:

    output[port_number] = 'CLOSE'
    pass

II. 多線程掃描端口

單線程掃描雖然邏輯簡單，但無疑是及其低效的。因為在掃描過程中要進(jìn)行大量的數(shù)據(jù)包的發(fā)送和接受，所以這是一個I/O密集型的操作。如果只是用單線程進(jìn)行掃描的話，程序會在等待回復(fù)的過程中浪費(fèi)大量的時間。因此多線程的操作是很有必要的。這里，一個很自然的思路就是為每一個端口單獨(dú)開一個線程進(jìn)行掃描。

在這里我們將需要掃描的端口列表定為從Nmap中得到的前1000個使用頻率最高的端口：

復(fù)制代碼 代碼如下:
__port_list = [1,3,6,9,13,17,19,20,21,22,23,24,25,30,32,37,42,49,53,70,79,80,81,82,83,84,88,89,99,106,109,110,113,119,125,135,139,143,146,161,163,179,199,211,222,254,255,259,264,280,301,306,311,340,366,389,406,416,425,427,443,444,458,464,481,497,500,512,513,514,524,541,543,544,548,554,563,...]

對于一個給定的ip地址，掃描的過程是這樣的：

1. 取出一個端口
2. 新建一條線程，利用__TCP_connect()函數(shù)對該(ip,port)進(jìn)行連接操作。
3. 調(diào)用thread.start()和thread.join()方法，使掃描的子線程開始工作并且命令主線程等待子線程死亡后再結(jié)束。
4. 重復(fù)這個過程直到所有的端口都被掃描過。

根據(jù)以上思路，多線程掃描的代碼如下：

"""
Open multiple threads to perform port scanning

Keyword arguments:
ip -- the ip address that is being scanned
delay -- the time in seconds that a TCP socket waits until timeout
output -- a dict() that stores result pairs in {port, status} style (status = 'OPEN' or 'CLOSE')
"""
def __scan_ports_helper(ip, delay, output):

  '''
  Multithreading port scanning
  '''

  port_index = 0

  while port_index < len(__port_list):

    # Ensure that the number of cocurrently running threads does not exceed the thread limit
    while threading.activeCount() < __thread_limit and port_index < len(__port_list):

      # Start threads
      thread = threading.Thread(target = __TCP_connect, args = (ip, __port_list[port_index], delay, output))
      thread.start()
      # lock the thread until all threads complete
      thread.join()
      port_index = port_index + 1

其中__thread_limit參數(shù)是用來限制線程數(shù)目的。output是一個字典，以(port: status)的形式保存了掃描的結(jié)果。
thread.join()保證了主線程只有在所有子線程都結(jié)束之后才會繼續(xù)執(zhí)行，從而確保了我們一定會掃描全部的端口。

III. 多線程掃描多個網(wǎng)站

在多線程掃描端口的同時，如果我們能夠多線程掃描多個網(wǎng)站，那么掃描的效率還將進(jìn)一步提高。為了達(dá)到這個目的，我們需要另一個線程去管理一個網(wǎng)站對應(yīng)的對其端口進(jìn)行掃描的所有子線程。

除此之外，在這種情況下，我們必須刪去__scan_ports_helper()中的thread.join()。否則主線程就會被端口掃描子線程阻塞，我們也就無法多線程掃描多個網(wǎng)站了。

在不使用join()的情況下，我們?nèi)绾未_保一個網(wǎng)站的掃描線程只有在完成對其全部端口的掃描之后才會返回呢？這里我使用的方法是檢測output字典的長度。因為在全部掃描完成后，output的長度一定與__port_list的長度一致。

改變后的代碼如下：

def __scan_ports_helper(ip, delay, output):

  '''
  Multithreading port scanning
  '''

  port_index = 0

  while port_index < len(__port_list):

    # Ensure that the number of cocurrently running threads does not exceed the thread limit
    while threading.activeCount() < __thread_limit and port_index < len(__port_list):

      # Start threads
      thread = threading.Thread(target = __TCP_connect, args = (ip, __port_list[port_index], delay, output))
      thread.start()
      port_index = port_index + 1

  while (len(output) < len(self.target_ports)):
    continue

根據(jù)以上掃描線程的代碼，端口掃描的管理線程的代碼如下所示：

"""
Controller of the __scan_ports_helper() function

Keyword arguments:
ip -- the ip address that is being scanned
delay -- the time in seconds that a TCP socket waits until timeout
"""    

def __scan_ports(websites, output_ip, delay):

  scan_result = {}

  for website in websites:
    website = str(website)
    scan_result[website] = {}

    thread = threading.Thread(target = __scan_ports_helper, args = (ip, delay, scan_result[website]))
    thread.start()
    # lock the script until all threads complete
    thread.join()

  return scan_result

至此，我們就完成了一個多線程端口掃描器的全部代碼。

IV. 總結(jié)！利用這些代碼掃描給定網(wǎng)站并輸出結(jié)果

處于輸出方便的考慮，我并沒有使用多線程掃描多個網(wǎng)站，同時對每個網(wǎng)站多線程掃描多個端口的方法。在這個例子中只進(jìn)行了多線程掃描端口，但同時只掃描一個網(wǎng)站的操作。整合起來的代碼如下：

import sys
import subprocess
import socket
import threading
import time

class PortScanner:

  # default ports to be scanned
  # or put any ports you want to scan here!
  __port_list = [1,3,6,9,13,17,19,20,21,22,23,24,25,30,32,37,42,49,53,70,79,80,81,82,83,84,88,89,99,106,109,110,113,119,125,135,139,143,146,161,163,179,199,211,222,254,255,259,264,280,301,306,311,340,366,389,406,416,425,427,443,444,458,464,481,497,500,512,513,514,524,541,543,544,548,554,563]
  # default thread number limit
  __thread_limit = 1000
  # default connection timeout time inseconds
  __delay = 10


  """
  Constructor of a PortScanner object

  Keyword arguments:
  target_ports -- the list of ports that is going to be scanned (default self.__port_list)
  """
  def __init__(self, target_ports = None):
    # If target ports not given in the arguments, use default ports
    # If target ports is given in the arguments, use given port lists
    if target_ports is None:
      self.target_ports = self.__port_list
    else:
      self.target_ports = target_ports


  """
  Return the usage information for invalid input host name. 
  """
  def __usage(self):
    print('python Port Scanner v0.1')
    print('please make sure the input host name is in the form of "something.com" or "http://something.com!"\n')


  """
  This is the function need to be called to perform port scanning

  Keyword arguments:
  host_name -- the hostname that is going to be scanned
  message -- the message that is going to be included in the scanning packets, in order to prevent
    ethical problem (default: '')
  """
  def scan(self, host_name, message = ''):

    if 'http://' in host_name or 'https://' in host_name:
      host_name = host_name[host_name.find('://') + 3 : ]

    print('*' * 60 + '\n')
    print('start scanning website: ' + str(host_name))

    try:
      server_ip = socket.gethostbyname(str(host_name))
      print('server ip is: ' + str(server_ip))

    except socket.error as e:
      # If the DNS resolution of a website cannot be finished, abort that website.

      #print(e)
      print('hostname %s unknown!!!' % host_name)

      self.__usage()

      return {}

      # May need to return specificed values to the DB in the future

    start_time = time.time()
    output = self.__scan_ports(server_ip, self.__delay, message)
    stop_time = time.time()

    print('host %s scanned in %f seconds' %(host_name, stop_time - start_time))

    print('finish scanning!\n')

    return output


  """
  Set the maximum number of thread for port scanning

  Keyword argument:
  num -- the maximum number of thread running concurrently (default 1000)
  """
  def set_thread_limit(self, num):
    num = int(num)

    if num <= 0 or num > 50000:

      print('Warning: Invalid thread number limit! Please make sure the thread limit is within the range of (1, 50,000)!')
      print('The scanning process will use default thread limit!')

      return

    self.__thread_limit = num


  """
  Set the time out delay for port scanning in seconds

  Keyword argument:
  delay -- the time in seconds that a TCP socket waits until timeout (default 10)
  """
  def set_delay(self, delay):

    delay = int(delay)
    if delay <= 0 or delay > 100:

      print('Warning: Invalid delay value! Please make sure the input delay is within the range of (1, 100)')
      print('The scanning process will use the default delay time')

      return 

    self.__delay = delay


  """
  Print out the list of ports being scanned
  """
  def show_target_ports(self):
    print ('Current port list is:')
    print (self.target_ports)


  """
  Print out the delay in seconds that a TCP socket waits until timeout
  """
  def show_delay(self):
    print ('Current timeout delay is :%d' %(int(self.__delay)))


  """
  Open multiple threads to perform port scanning

  Keyword arguments:
  ip -- the ip address that is being scanned
  delay -- the time in seconds that a TCP socket waits until timeout
  output -- a dict() that stores result pairs in {port, status} style (status = 'OPEN' or 'CLOSE')
  message -- the message that is going to be included in the scanning packets, in order to prevent
    ethical problem (default: '')
  """
  def __scan_ports_helper(self, ip, delay, output, message):

    '''
    Multithreading port scanning
    '''

    port_index = 0

    while port_index < len(self.target_ports):

      # Ensure that the number of cocurrently running threads does not exceed the thread limit
      while threading.activeCount() < self.__thread_limit and port_index < len(self.target_ports):

        # Start threads
        thread = threading.Thread(target = self.__TCP_connect, args = (ip, self.target_ports[port_index], delay, output, message))
        thread.start()
        port_index = port_index + 1


  """
  Controller of the __scan_ports_helper() function

  Keyword arguments:
  ip -- the ip address that is being scanned
  delay -- the time in seconds that a TCP socket waits until timeout
  message -- the message that is going to be included in the scanning packets, in order to prevent
    ethical problem (default: '')
  """    
  def __scan_ports(self, ip, delay, message):

    output = {}

    thread = threading.Thread(target = self.__scan_ports_helper, args = (ip, delay, output, message))
    thread.start()

    # Wait until all port scanning threads finished
    while (len(output) < len(self.target_ports)):
      continue

    # Print openning ports from small to large
    for port in self.target_ports:
      if output[port] == 'OPEN':
        print(str(port) + ': ' + output[port] + '\n')

    return output



  """
  Perform status checking for a given port on a given ip address using TCP handshake

  Keyword arguments:
  ip -- the ip address that is being scanned
  port_number -- the port that is going to be checked
  delay -- the time in seconds that a TCP socket waits until timeout
  output -- a dict() that stores result pairs in {port, status} style (status = 'OPEN' or 'CLOSE')
  message -- the message that is going to be included in the scanning packets, in order to prevent
    ethical problem (default: '')
  """
  def __TCP_connect(self, ip, port_number, delay, output, message):
    # Initilize the TCP socket object
    TCP_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    TCP_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
    TCP_sock.settimeout(delay)


    # Initilize a UDP socket to send scanning alert message if there exists an non-empty message
    if message != '':
      UDP_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
      UDP_sock.sendto(str(message), (ip, int(port_number)))

    try:
      result = TCP_sock.connect_ex((ip, int(port_number)))
      if message != '':
        TCP_sock.sendall(str(message))

      # If the TCP handshake is successful, the port is OPEN. Otherwise it is CLOSE
      if result == 0:
        output[port_number] = 'OPEN'
      else:
        output[port_number] = 'CLOSE'

      TCP_sock.close()

    except socket.error as e:

      output[port_number] = 'CLOSE'
      pass

以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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