如何知道paramiko SSH频道是否断开？
如何知道paramiko SSH频道是否断开？
提问于 2013-11-22 14:59:23
我正在设计使用paramiko进行SSH连接的测试用例。测试用例通常包含paramiko.exec_command()调用，我有一个包装器(称为run_command())。在这里，self.ssh是paramiko.SSHClient()的意图。在每次调用之前，我使用一个装饰器来检查ssh连接。(self.get_ssh()协商连接)
def check_connections(function):
''' A decorator to check SSH connections. '''
def deco(self, *args, **kwargs):
if self.ssh is None:
self.ssh = self.get_ssh()
else:
ret = getattr(self.ssh.get_transport(), 'is_active', None)
if ret is None or (ret is not None and not ret()):
self.ssh = self.get_ssh()
return function(self, *args, **kwargs)
return deco@check_connections
def run_command(self, command):
''' Executes command via SSH. '''
stdin, stdout, stderr = self.ssh.exec_command(command)
stdin.flush()
stdin.channel.shutdown_write()
ret = stdout.read()
err = stderr.read()
if ret:
return ret
elif err:
return err
else:
return None直到我的远程节点重新启动时，它才能完美地工作，这种情况有时会发生。当它发生时，下一个run_command()调用将生成一个socket.error异常。问题是，在抛出异常之前，paramiko.Transport对象似乎处于活动状态：
Python 2.7.3 (default, Mar 7 2013, 14:03:36)
[GCC 4.3.4 [gcc-4_3-branch revision 152973]] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> import paramiko
>>> ssh = paramiko.SSHClient()
>>> print ssh
<paramiko.SSHClient object at 0x7f2397b96d50>
>>> print ssh.get_transport()
None
>>> ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
>>> ssh.load_host_keys(os.path.expanduser('~') + '/.ssh/known_hosts')
>>> ssh.connect(hostname = '172.31.77.57', username = 'root', password = 'rootroot', timeout = 5.0)
>>> print ssh
<paramiko.SSHClient object at 0x7f2397b96d50>
>>> print ssh.get_transport()
<paramiko.Transport at 0x97537550L (cipher aes128-ctr, 128 bits) (active; 0 open channel(s))>
>>> print ssh.get_transport().is_active()
True
>>> ssh.exec_command('ls')
(<paramiko.ChannelFile from <paramiko.Channel 1 (open) window=2097152 -> <paramiko.Transport at 0x97537550L (cipher aes128-ctr, 128 bits) (active; 1 open channel(s))>>>, <paramiko.ChannelFile from <paramiko.Channel 1 (open) window=2097152 -> <paramiko.Transport at 0x97537550L (cipher aes128-ctr, 128 bits) (active; 1 open channel(s))>>>, <paramiko.ChannelFile from <paramiko.Channel 1 (open) window=2097152 -> <paramiko.Transport at 0x97537550L (cipher aes128-ctr, 128 bits) (active; 1 open channel(s))>>>)
>>> print ssh
<paramiko.SSHClient object at 0x7f2397b96d50>
>>> print ssh.get_transport()
<paramiko.Transport at 0x97537550L (cipher aes128-ctr, 128 bits) (active; 0 open channel(s))>
>>> print ssh.get_transport().is_active()
True
>>> ssh.exec_command('reboot')
(<paramiko.ChannelFile from <paramiko.Channel 2 (open) window=2097152 -> <paramiko.Transport at 0x97537550L (cipher aes128-ctr, 128 bits) (active; 1 open channel(s))>>>, <paramiko.ChannelFile from <paramiko.Channel 2 (open) window=2097152 -> <paramiko.Transport at 0x97537550L (cipher aes128-ctr, 128 bits) (active; 1 open channel(s))>>>, <paramiko.ChannelFile from <paramiko.Channel 2 (open) window=2097152 -> <paramiko.Transport at 0x97537550L (cipher aes128-ctr, 128 bits) (active; 1 open channel(s))>>>)
>>> print ssh
<paramiko.SSHClient object at 0x7f2397b96d50>
>>> print ssh.get_transport()
<paramiko.Transport at 0x97537550L (cipher aes128-ctr, 128 bits) (active; 0 open channel(s))>
>>> print ssh.get_transport().is_active()
True
>>> ssh.exec_command('ls')
No handlers could be found for logger "paramiko.transport"
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/pytest/lib/python2.7/site-packages/paramiko/client.py", line 370, in exec_command
chan = self._transport.open_session()
File "/home/pytest/lib/python2.7/site-packages/paramiko/transport.py", line 662, in open_session
return self.open_channel('session')
File "/home/pytest/lib/python2.7/site-packages/paramiko/transport.py", line 764, in open_channel
raise e
socket.error: [Errno 104] Connection reset by peer
>>> print ssh
<paramiko.SSHClient object at 0x7f2397b96d50>
>>> print ssh.get_transport()
<paramiko.Transport at 0x97537550L (unconnected)>
>>> print ssh.get_transport().is_active()
False
>>>问题:如何确定连接是否处于活动状态？
回答 4
Stack Overflow用户
发布于 2013-11-23 10:25:06
在python中，它是easier to ask for forgiveness than permission。
将每个对ssh.exec_command的调用包装如下：
try:
ssh.exec_command('ls')
except socket.error as e:
# Crap, it's closed. Perhaps reopen and retry?Stack Overflow用户
发布于 2014-05-22 20:08:59
我的解决方案基本上和你的一样，只是组织得不一样：
def connection(self):
if not self.is_connected():
self._ssh = paramiko.SSHClient()
self._ssh.connect(self.server, self.port,
username = self.username, password = self.password)
return self._ssh
def is_connected(self):
transport = self._ssh.get_transport() if self._ssh else None
return transport and transport.is_active()
def do_something(self):
self.connection().exec_command('ls')Stack Overflow用户
发布于 2017-01-11 16:37:41
这样做是可行的：
import paramiko
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy()) # Setting the missing host policy to auto add it
client.connect('192.168.1.16', port=22, username='admin', password='admin', timeout=3, banner_timeout=2)
channel = client.invoke_shell() # Request an interactive shell session on this channel. If the server allows it, the channel will then be directly connected to the stdin, stdout, and stderr of the shell.
print channel.closed # False
command = 'reboot'
channel.send(command + '\n')
# wait a while
print channel.closed # True页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/20147902
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