如何使用Paramiko保持ssh会话不过期？

Question

我打算使用paramiko在远程主机上运行几个命令，但ssh会话在运行一个命令后关闭。
下面列出的代码：

from paramiko import SSHClient  
import paramiko  
ssh = SSHClient()
ssh.load_system_host_keys()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(host, 22, user, passwd, timeout=3)
stdin, stdout, stderr = ssh.exec_command('uname -a')

那么有什么方法可以阻止ssh会话关闭吗？或者帕拉米科的替代品？

>>> print ssh.get_transport()  
>>> <paramiko.Transport at 0xf00216d0L (unconnected)>  
>>> print ssh.get_transport().is_active()  
>>> False  
>>> print ssh.get_transport().is_authenticated()  
>>> False

有什么方法可以让paramiko ssh会话一直处于活动状态吗？

paramiko调试模式信息返回如下：

启动线程（客户端模式）:0x2657E10L
已连接（版本1.99，客户端组件-5.20）
kex ALGOS:[u'diffie-hellman-group-exchange-sha1',u'diffie-hellman-group14-sha1',u'diffie-hellman-group1-sha1']服务器密钥:[u'ssh-rsa']客户端加密:[u'aes128-cbc',u'3des-cbc',u'des-cbc']服务器加密:[u'aes128-cbc',u'3des-cbc',u'des-cbc']客户端服务器密钥类型SSH-RSA；密码：本地aes128-cbc,远程aes128-cbc；MAC：本地hmac-sha1，远程hmac-sha1；压缩：本地无、远程无
切换到新密钥...
用户身份验证正常
身份验证（密码）成功！
[chan 0]最大数据包输入：32768字节
[chan 1]最大数据包输入：32768字节
[chan 0]最大数据包输出：32496字节
Secsh通道0已打开。
Secsh通道2打开失败:
资源短缺：资源短缺
[chan 0]Secsh通道0请求确定
[chan 0]EOF已发送（0）

Answer 1

您可以使用paramiko实现交互式shell，这样在远程shell上执行命令后通道就不会关闭。

import paramiko
import re


class ShellHandler:

    def __init__(self, host, user, psw):
        self.ssh = paramiko.SSHClient()
        self.ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        self.ssh.connect(host, username=user, password=psw, port=22)

        channel = self.ssh.invoke_shell()
        self.stdin = channel.makefile('wb')
        self.stdout = channel.makefile('r')

    def __del__(self):
        self.ssh.close()

    @staticmethod
    def _print_exec_out(cmd, out_buf, err_buf, exit_status):
        print('command executed: {}'.format(cmd))
        print('STDOUT:')
        for line in out_buf:
            print(line, end="")
        print('end of STDOUT')
        print('STDERR:')
        for line in err_buf:
            print(line, end="")
        print('end of STDERR')
        print('finished with exit status: {}'.format(exit_status))
        print('------------------------------------')
        pass

    def execute(self, cmd):
        """

        :param cmd: the command to be executed on the remote computer
        :examples:  execute('ls')
                    execute('finger')
                    execute('cd folder_name')
        """
        cmd = cmd.strip('\n')
        self.stdin.write(cmd + '\n')
        finish = 'end of stdOUT buffer. finished with exit status'
        echo_cmd = 'echo {} $?'.format(finish)
        self.stdin.write(echo_cmd + '\n')
        shin = self.stdin
        self.stdin.flush()

        shout = []
        sherr = []
        exit_status = 0
        for line in self.stdout:
            if str(line).startswith(cmd) or str(line).startswith(echo_cmd):
                # up for now filled with shell junk from stdin
                shout = []
            elif str(line).startswith(finish):
                # our finish command ends with the exit status
                exit_status = int(str(line).rsplit(maxsplit=1)[1])
                if exit_status:
                    # stderr is combined with stdout.
                    # thus, swap sherr with shout in a case of failure.
                    sherr = shout
                    shout = []
                break
            else:
                # get rid of 'coloring and formatting' special characters
                shout.append(re.compile(r'(\x9B|\x1B\[)[0-?]*[ -/]*[@-~]').sub('', line).
                             replace('\b', '').replace('\r', ''))

        # first and last lines of shout/sherr contain a prompt
        if shout and echo_cmd in shout[-1]:
            shout.pop()
        if shout and cmd in shout[0]:
            shout.pop(0)
        if sherr and echo_cmd in sherr[-1]:
            sherr.pop()
        if sherr and cmd in sherr[0]:
            sherr.pop(0)

        self._print_exec_out(cmd=cmd, out_buf=shout, err_buf=sherr, exit_status=exit_status)
        return shin, shout, sherr