在pexpect python期间root身份验证失败

下面的观察结果并非总是如此，但是一段时间后用root用户和正确的密码用ssh多次访问SUT，python代码遇到了麻烦：

Apr 25 05:51:56 SUT sshd[31570]: pam_tally2(sshd:auth): user root (0) tally 83, deny 10
Apr 25 05:52:16 SUT sshd[31598]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=10.10.10.13  user=root
Apr 25 05:52:21 SUT sshd[31568]: error: PAM: Authentication failure for root from 10.10.10.13
Apr 25 05:52:21 SUT sshd[31568]: Connection closed by 10.10.10.13 [preauth]

这是下面的python代码：

COMMAND_PROMPT = '.*:~ #'
SSH_NEWKEY = '(?i)are you sure you want to continue connecting'

def scp(source, dest, password):
    cmd = 'scp ' + source + ' ' + dest
    try:
        child = pexpect.spawn('/bin/bash', ['-c', cmd], timeout=None)
        res = child.expect([pexpect.TIMEOUT, SSH_NEWKEY, COMMAND_PROMPT, '(?i)Password'])
        if res == 0:
            print('TIMEOUT Occurred.')
        if res == 1:
            child.sendline('yes')
            child.expect('(?i)Password')
            child.sendline(password)
            child.expect([pexpect.EOF], timeout=60)
        if res == 2:
            pass
        if res == 3:
            child.sendline(password)
            child.expect([pexpect.EOF], timeout=60)
    except:
        print('File not copied!!!')
        self.logger.error(str(self.child))

当ssh不成功时，这是pexpect打印输出：

version: 2.3 ($Revision: 399 $)
command: /usr/bin/ssh
args: ['/usr/bin/ssh', 'root@100.100.100.100']
searcher: searcher_re:
    0: re.compile(".*:~ #")
buffer (last 100 chars): :
Account locked due to 757 failed logins

Password:
before (last 100 chars): :
Account locked due to 757 failed logins

Password:
after: <class 'pexpect.TIMEOUT'>
match: None
match_index: None
exitstatus: None
flag_eof: False
pid: 2284
child_fd: 5
closed: False
timeout: 30
delimiter: <class 'pexpect.EOF'>
logfile: None
logfile_read: None
logfile_send: None
maxread: 2000
ignorecase: False
searchwindowsize: None
delaybeforesend: 0
delayafterclose: 0.1
delayafterterminate: 0.1

任何线索可能是什么，是否可能在我的SUT上为pam身份验证配置了任何缺失或错误？问题是，当SUT以这个pam故障开始时，python代码将始终有问题，只有重新启动SUT似乎有帮助:(

通过ssh root @ ...手动访问SUT总是有效，即使pexpect不能！该帐户似乎没有锁定根据：

SUT:~ # passwd -S root
root P 04/24/2017 -1 -1 -1 -1

我已经研究了其他一些问题，但没有提到真正的解决方案或者可以使用我的python代码 .

谢谢你 .