Python 预计属性错误。 'NoneType' 没有属性 'sendline'

Question

正在使用 Pexpect 编写脚本以通过 ssh 连接，但它抛出属性错误。

import pexpect
PROMPT = ['# ', '>>> ', '> ', '$ ', '~# ']
def send_command(child, cmd):
    child.sendline(cmd)
    child.expect(PROMPT)
    print child.before, child.after
def connect(user, host, password):
    ssh_newkey = 'Are you sure you want to continue connecting (yes/no)?'
    connStr = 'ssh ' + user + '@' + host
    child = pexpect.spawn(connStr)
    ret = child.expect([ssh_newkey, 'password:'])
    if ret == 0:
        print '[-] Error Connecting'
        return
    elif ret == 1:
        child.sendline('yes')
        ret = child.expect('password:')
        if ret == 0:
            print '[-] Error Connecting'
            return
    child.sendline(password)
    child.expect(PROMPT)
    return child
def main():
    host = 'test.rebex.net'
    user = 'demo'
    password = 'password'
    child = connect(user, host, password)
    send_command(child, 'cat /etc/shadow | grep root')
if __name__ == '__main__':
    main()

我收到以下错误：

[-] Error Connecting
Traceback (most recent call last):
  File "./bruteSSH.py", line 33, in <module>
    main()
  File "./bruteSSH.py", line 31, in main
    send_command(child, 'cat /etc/shadow | grep root')
  File "./bruteSSH.py", line 6, in send_command
    child.sendline(cmd)
AttributeError: 'NoneType' object has no attribute 'sendline'

我认为这与我的子对象是 'NoneType' 有关，但我无法确定我做错了什么。

Answer 1

首先你在第 6 行的缩进是错误的。

导致此错误的原因是子对象尚未正确设置和连接成功。

如果这正是您的代码，那么问题是 "child.sendline()" 在函数外部执行，而 child 是函数内部的局部变量 "send_command" 所以在全球范围内，子变量尚未定义

Answer 2

您 return 有几个条件没有值。这就是您获得 None 的地方以及导致错误的原因。请参阅下面的注释行：

if ret == 0:
    print '[-] Error Connecting'
    return  # THIS WILL CAUSE YOUR ERROR

elif ret == 1:
    child.sendline('yes')
    ret = child.expect('password:')
    if ret == 0:
        print '[-] Error Connecting'
        return  # THIS WILL ALSO CAUSE YOUR ERROR

但无论如何你的逻辑是有缺陷的。如果将数组传递给它，则期望 returns 为 0 或匹配项的索引。在您的代码中，您将一个数组传递给它。因此，return 值为 0 表示它成功匹配您的第一个条目 - "Are you sure" 条件。如果你匹配，你想发送 "yes"。以下是我认为您想要的更多内容...

import pexpect
PROMPT = ['# ', '>>> ', '> ', '$ ', '~# ']
def send_command(child, cmd):
    child.sendline(cmd)
    child.expect(PROMPT)
    print child.before, child.after

def connect(user, host, password):
    ssh_newkey = 'Are you sure you want to continue connecting (yes/no)?'
    connStr = 'ssh ' + user + '@' + host
    child = pexpect.spawn(connStr)
    ret = child.expect(['password:', ssh_newkey])
    if ret == 1:
        child.sendline('yes')
        ret = child.expect('password:')
    if ret != 0:
        print '[-] Error Connecting'
        return  # THIS WILL RETURN A NONE SO YOU SHOULD CHECK FOR IT.  SHOULD EXPLICITLY DO A return None TO MAKE IT CLEARER
    child.sendline(password)
    child.expect(PROMPT)
    return child

def main():
    host = 'localhost'
    user = 'demo'
    password = 'password'
    child = connect(user, host, password)
    if child is not None:
        send_command(child, 'cat /etc/shadow | grep root')
    else:
        print "Problem connecting!"

if __name__ == '__main__':
    main()

Answer 3

问题就在你面前。当您在连接函数中遇到“[*] 错误连接”打印语句所示的错误时，您 return 什么都没有。仅当连接成功时，它 return 才是子对象，但当连接失败时，您会 return 一个 "Null Object" 并退出您的函数。您无法建立成功的连接，因此子对象永远不会 returned 到您的主函数中的 "child" 变量。并且您将相同的 "Null Object" 传递给您的 send_command() 因此不起作用


import sys

def connect(user, host, password):
    ssh_newkey = 'Are you sure you want to continue connecting (yes/no)?'
    connStr = 'ssh ' + user + '@' + host
    child = pexpect.spawn(connStr)
    ret = child.expect([ssh_newkey, 'password:'])
    if ret == 0:
        print '[-] Error Connecting'
        sys.exit()
    elif ret == 1:
        child.sendline('yes')
        ret = child.expect('password:')
        if ret == 0:
            print '[-] Error Connecting'
            sys.exit()
    child.sendline(password)
    child.expect(PROMPT)
    return child

现在您的程序只有在连接成功时才会继续。可能期望和密码错误，总体问题是无法成功连接

Python 预计属性错误。 'NoneType' 没有属性 'sendline'

Python Pexpect Attribute error. 'NoneType' has no attribute 'sendline'

python

attributes

pexpect

nonetype

正在使用 Pexpect 编写脚本以通过 ssh 连接，但它抛出属性错误。

我收到以下错误：

我认为这与我的子对象是 'NoneType' 有关，但我无法确定我做错了什么。