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python use netmiko for embedded ssh


2 description

We need a python script to auto test our boards, and we use ssh to connect the boards.

Then we found Paramiko, but Paramiko frequently raises EOF in transport thread issue.

We got the reason from:

http://www.paramiko.org/faq.html#paramiko-doesn-t-work-with-my-cisco-windows-or-other-non-unix-system

Then netmiko comes.

It's a multi-vendor library to simplify Paramiko SSH connections to network devices.

3 install

install netmiko as below: 

sudo pip install netmiko

4 netmiko sample

The netmiko sample with multiple threads support: 

#!/usr/bin/env python3

import netmiko
import threading
import time
import sys
import os

def ssh2(ip, username, passwd, cmd):
  threadname = threading.currentThread().getName()
  print('checking %s [%s]' % (ip, threadname))

  net_connect = netmiko.ConnectHandler(device_type='cisco_ios', ip=ip,
                                       username=username, password=passwd)

  output = net_connect.send_command(command_string=cmd, strip_prompt=False,
                                    strip_command=False, delay_factor=5)
  print(output)
  net_connect.disconnect()

if __name__=='__main__':
  cmd = "cat /proc/version"
  username = "root"
  passwd = "123abc"

  print("\n\n>>>>>>>>> Start <<<<<<<<<")
  threads = []
  for i in range(100, 120):
    ip = '192.168.0.' + str(i)
    if os.system("ping -c 1 %s >/dev/null" % ip) == 0:
      a = threading.Thread(target=ssh2, args=(ip, username, passwd, cmd))
      a.start()
      threads.append(a)
      time.sleep(0.5)
    else:
      print("%s not alive" % ip)

  for t in threads:
    t.join()

  print(">>>>>>>>> End <<<<<<<<<")
  • send_command timeout max = delay_factor * 0.2 * 500
  • strip_command=False, then command contained in output
  • strip_prompt=False, then the board prompt contained in output