def ssh_exec_command(ip, username, password, cmd=None):

     """

     ssh执行命令

     :param ip:  IP address for target machine

     :param username:

     :param password:

     :param cmd:  Prepare for execute commands on target machine

     :return:

     """

     try:

         ssh = paramiko.SSHClient()

         # add host_allow

         ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())

         # use secret-key login remote machines

         # private_keys = paramiko.RSAKey.from_private_key_file(pkey_path)

         ssh.connect(hostname=str(ip), port=22, username=username, password=password)

         stdin, stdout, stderr = ssh.exec_command(cmd)

         stdout_result = stdout.readlines()

         stderr_result = stderr.readlines()

         if stderr_result:

             return False

         else:

             return stdout_result

     except Exception as e:

         print(str(e))

         return False

     finally:

         ssh.close()