使用pysftp和Python3连接到SFTP服务器，仅使用服务器指纹

Question

我遇到了一种奇怪的情况，第一次需要连接到SFTP服务器，但似乎找不到访问该服务器已知主机条目的方法。如果我说：

import pysftp
cnopts = pysftp.CnOpts()
cnopts.hostkeys = None
with pysftp.Connection('host', username='me', password='pass', cnopts=cnopts):

但显然这让你容易受到中间人的攻击。因此，我尝试连接：

cnopts = pysftp.CnOpts(knownhosts='config/known_host')
cnopts.hostkeys = None

with pysftp.Connection(host, username=username, password=password, cnopts=cnopts) as sftp:

我会收到各种各样的错误信息。最近的一次是：

我运气不好吗？我是不是应该绕过钥匙检查？

Answer 1

可以在python-pysftp/paramiko-verify host key（使用其指纹）中找到解决方案，但为了使用Python3，我不得不对其进行一些修改。

import hashlib as hl


def trim_fingerprint(fingerprint):
    #if fingerprint.startswith('ecdsa-sha2-nistp384 384 '):
        #return fingerprint[len('ecdsa-sha2-nistp384 384 '):]
    return fingerprint


def clean_fingerprint(fingerprint):
    #return trim_fingerprint(fingerprint).replace(':', '')
    return trim_fingerprint(fingerprint)

class FingerprintKey:

    def __init__(self, fingerprint):
        self.fingerprint = clean_fingerprint(fingerprint)

    def compare(self, other):
        if callable(getattr(other, "get_fingerprint", None)):
            return other.get_fingerprint() == self.fingerprint
        elif clean_fingerprint(other) == self.get_fingerprint():
            return True
        #elif hl.md5(other).digest().encode('hex') == self.fingerprint:
        #The line below is required for Python 3.  Above is Python 2.
        elif hl.md5(other).hexdigest() == self.fingerprint:
            return True
        else:
            return False

    def __cmp__(self, other):
        return self.compare(other)

    def __contains__(self, other):
        return self.compare(other)

    def __eq__(self, other):
        return self.compare(other)

    def __ne__(self, other):
        return not self.compare(other)

    def get_fingerprint(self):
        return self.fingerprint

    def get_name(self):
        return u'ecdsa-sha2-nistp384'

    def asbytes(self):
         # Note: This returns itself.
         #   That way when comparisons are done to asbytes return value,
         #   this class can handle the comparison.
        return self

我不得不手动删除指纹中的任何“：”，因为它从来不起作用，允许脚本这样做。

用法：

options = pysftp.CnOpts()
options.hostkeys.clear()
options.hostkeys.add('www.sample.com', u'ecdsa-sha2-nistp384 384 ', AuthOnFingerPrint.FingerprintKey(serverkey))