python - 暴力 python : port inputs not being seperated

Question

所以我在学习 Python 的同时从“Violent Python”开始黑客攻击，我遇到了一个问题这是我的代码:

import optparse
import socket
from socket import *
from threading import *

screenLock = Semaphore(value = 1)

def connScan(tgtHost, tgtPort):
    try:
        connSkt = socket(AF_INET, SOCK_STREAM)
        connSkt.connect((tgtHost, tgtPort))
        connSkt.send('ViolentPython\r\n')
        results = connSkt.recv(100)
        screenLock.acquire()
        print '[+]%d/tcp open' %tgtPort
        print '[+] ' + str(results)
    except:
        screenLock.acquire()
        print '[-]%d/tcp closed' %tgtPort
    finally:
        screenLock.release()
        connSkt.close()
def portScan(tgtHost, tgtPorts):
    try:
        tgtIP = gethostbyname(tgtHost)
    except:
        print "[-] Cannot resolve '%s': Unknown host" %tgtHost
        return
    try:
        tgtName = gethostbyaddr(tgtIP)
        print '\n[+] Scan Results for ' +tgtName[0]
    except:
        print '\n[+] Scan Results for ' +tgtIP
    setdefaulttimeout(10)
    for tgtPort in tgtPorts:
        print 'Scanning port ' +tgtPort
        t = Thread(target=connScan, args=(tgtHost, int(tgtPort)))
        t.start()
def main():
    parser = optparse.OptionParser('usage %prog ' +\
    '-H <target host> -p <target port>')
    parser.add_option('-H', dest='tgtHost', type='string', \
        help='specify target host')
    parser.add_option('-p', dest='tgtPort', type='string', \
        help='specify target port[s] seperated by a comma')
    (options, args) = parser.parse_args()
    tgtHost = options.tgtHost
    tgtPorts = str(options.tgtPort).split(', ')
    if (tgtHost == None) | (tgtPorts[0] == None):
        print parser.usage
        exit(0)
    portScan(tgtHost, tgtPorts)
if __name__ == '__main__':
    main()

运行程序我收到以下错误消息:

  File "port_scanner.py", line 54, in <module>
    main()
  File "port_scanner.py", line 52, in main
    portScan(tgtHost, tgtPorts)
  File "port_scanner.py", line 37, in portScan
    t = Thread(target=connScan, args=(tgtHost, int(tgtPort)))
ValueError: invalid literal for int() with base 10: '21,'

有人可以帮忙吗？我对此还是个新手，但我猜 Python 不会通过运行此命令来分隔我输入的不同端口:

python port_scanner.py -H 74.207.244.221 -p 21, 22, 80

我定位的 ip 是 scanme.org，用于扫描。谢谢!

Answer 1

首先，您误解了命令行的解析方式。

你传入:

python port_scanner.py -H 74.207.244.221 -p 21, 22, 80

这意味着 Python 看到:

['-H', '74.207.244.221', '-p', '21,', '22,', '80']

optparse.OptionParser 因此解析just '21,' 作为-p 的值转变。因此，options.tgtPort 被设置为 '21,'，并且对该值的 .split(', ') 导致 ['21,'] 因为该输入字符串中没有 ', '(逗号和空格)。

要在参数中包含空格，请在命令行中使用引号:

python port_scanner.py -H 74.207.244.221 -p "21, 22, 80"

但您真的想调整命令行解析以仅分隔逗号并容忍空格:

tgtPorts = [p.strip() for p in options.tgtPort.split(',')]

另一件需要理解的事情是，使用 .split() 拆分字符串将生成一个包含至少一个元素的列表:

>>> 'foo'.split(',')
['foo']

因此您对 tgtPorts[0] == None 的测试将始终为 False。请注意，正常的 Python 习语是使用 is 代替 None(tgtPorts[0] is None)，因为 None 是单例。