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Device Automation with Netmiko

Multi-vendor library to simplify CLI connections to network devices

Network automation to screen-scraping devices is primarily concerned with gathering output from show commands and with making configuration changes.

Why Netmiko?

Network automation to screen-scraping devices is primarily concerned with gathering output from show commands and with making configuration changes. Netmiko aims to accomplish both of these operations and to do it across a very broad set of platforms. It seeks to do this while abstracting away low-level state control (i.e. eliminate low-level regex pattern matching to the extent practical)

This is where the basics starts and in order to get complete hands -on will need virtual lab where you can configure some devices. This lab will use containerlab.

Install and setup Containerlab

This will quickly install clab:

curl -sL https://containerlab.dev/setup | sudo -E bash -s "all"

Topology

  1. Save this yaml file
# clab-protocol-demo.clab.yaml
name: protocol-lab

topology:
  nodes:
    srl1:
      kind: srl
      image: ghcr.io/nokia/srlinux:latest
  1. Deploy the lab
containerlab deploy -t clab-ssh-demo.yaml
  1. Inspect the topology to get the ip address
containerlab inspect -t clab-ssh-demo.yaml

Deploy this lab to get a complete hands on netmiko lab

Example Usage

This is a simple script that uses netmiko to connect to a nokia device and backup running configuration

  1. Define connection details
  2. Generate a timestamp
  3. Connect via Netmiko
  4. Retrieve the running config
  5. Save it to a file named config_backup_.txt
  6. Disconnect
#!/usr/bin/env python3
# simple_backup_nokia_srl.py
# Beginner-friendly script to backup Nokia SR Linux configuration (with paging disabled)

import datetime
from netmiko import ConnectHandler

# 1. Define the router connection details
#    Updated for your SR Linux containerlab instance
device = {
    'device_type': 'nokia_srl',    # Nokia SR Linux driver
    'host': '172.20.20.2',          # Router IP address
    'username': 'admin',            # Login username
    'password': 'NokiaSrl1!',       # Login password
}

# 2. Build a timestamp for file naming
now = datetime.datetime.now()
timestamp = now.strftime('%Y%m%d_%H%M%S')  # e.g. 20250717_162530

# 3. Connect to the router over SSH
print('Connecting to the router...')
connection = ConnectHandler(**device)

# 4. Disable paging so the full output returns in one go
print('Disabling paging...')
connection.send_command_timing('screen-length 0 temporary')

# 5. Ask the router to show its configuration file in JSON
print('Retrieving configuration JSON...')
config_output = connection.send_command_timing('bash cat /etc/opt/srlinux/config.json')

# 6. Save the configuration to a file
filename = f'config_backup_{timestamp}.json'
print(f'Saving configuration in {filename}...')
with open(filename, 'w') as file:
    file.write(config_output)

# 7. Close the SSH connection
connection.disconnect()
print('Done! Router configuration backed up.')

Output shall look like this, the config file will be saved in working directory.

Connecting to the router...
Disabling paging...
Retrieving configuration...
Saving configuration in config_backup_20250717_140101.txt...
Done! Router configuration backed up.

Challenge

Write a script which:

  1. Use input() to ask for your SR-OS “show” command.

  2. Connect with Netmiko, disable paging (screen-length 0 temporary), run the command with send_command_timing(), print the output, and disconnect.

Reference