Netmiko Library

By Kirk Byers

Since late 2014, I have been working on an open-source Python library that simplifies SSH management to network devices. The library is based on the Paramiko SSH library and is named Netmiko.

You can find the library here and the latest released version of the software can be downloaded here.

The purposes of the library are the following:

Python, Paramiko SSH, and Network Devices

By Kirk Byers

You have been learning Python, but as a network engineer what can you do with it? In this article, I will show you how to use Paramiko SSH (a Python SSH library) to connect to and gather information from a router. In a later article (potentially multiple articles), I will expand upon this—showing you how to gather information from multiple devices, and how to make configuration changes.

Now in this article I will be using Python to connect to an interface that is inherently expecting a human being (i.e. using an 'Expect-like' method). For various reasons, this Expect-like method is problematic—for example, there can be timing issues; there can be unexpected interaction problems...

Automating Cisco IOS

By Kirk Byers

I recently started working on a method to automate various tasks in Cisco IOS using Python and Ansible. The general method consists of an SSH control channel and a separate SCP channel to transfer files.

Once you have a reliable, programmatic file transfer mechanism, then there are several interesting automation use cases--loading new software images; loading a device's initial configuration; restoring a configuration (for a failed device); loading configuration changes (configuration merge); and loading a completely new configuration file (configure replace).

Arista and Ansible using pyeapi

By Kirk Byers

Arista recently created a library called pyeapi and they have integrated this library into their Ansible modules.

pyeapi itself is fairly staightforward to use. The main gotcha is that you need to create a .eapi.conf file in your home directory. This file contains information about the connection:

Ansible and Dynamic Inventory

By Kirk Byers

So you are chugging along using Ansible, but are having problems maintaining your Ansible inventory.

Remember, Ansible uses inventory information about hosts and groups of hosts to connect to and manage client devices. By default, inventory information is stored in /etc/ansible/hosts. This inventory information can also be expanded to include the 'group_vars' and 'host_vars' directories.

An example, Ansible inventory file could look like the following:

Juniper's PyEZ - Loading Configuration Changes

By Kirk Byers

Juniper has a Python library known as PyEZ which was created to simplify the programmatic management and control of Juniper devices.

You can find the PyEZ library at: https://github.com/Juniper/py-junos-eznc

This library relies upon the Junos API which uses NETCONF. NETCONF is a standardized protocol that facilitates the programmatic control and management of network devices. It was first published in December of 2006 in RFC4741 and was later revised in RFC6241.

Juniper's PyEZ - Commit, Confirm, Rollback

By Kirk Byers

In the last article, we loaded configuration changes from a file using PyEZ. Now let's look at some other aspects of PyEZ and configuration file management.

First, let's lock the candidate config so that no one else can make changes:

Getting Started with Juniper and Ansible

By Kirk Byers

In this article, I will discuss the steps required to use Ansible on Juniper equipment. We will then use Ansible to gather facts from a Juniper SRX. Finally, we will use Ansible to transfer a small configuration change to the SRX.

For more information on Ansible, see the following:

Network Config Templating using Ansible, Part1

By Kirk Byers

In this article, I will show you how to use Ansible to generate network device configurations based on a template and a variables file. The article presupposes that you have Ansible installed on your system and you have some basic familiarity with Ansible. The Ansible documentation is very good. You can find it at http://docs.ansible.com/. You might want to read through the Getting Started section and through some of the Intro to Playbooks section. Both of these sections are fairly short.

The general problem that we are trying to solve is—we want a systematic way of creating network device configurations based on templates and variables.

Network Config Templating using Ansible, Part2

By Kirk Byers

In Part1 of this series, I established a basic framework for using Ansible for network device configuration templating. In this article, I am going to expand upon this to generate the entire router configuration for five fictional remote-office routers.

As a quick reminder, we have three parts to our templating system—1)the tasks file (tasks/main.yml), 2)the vars file (vars/main.yml), and 3)the template file (templates/router.j2). These are all organized under an Ansible role (in my example, ./RTR-TEMPLATE/roles/router).

Network Config Templating using Ansible, Part3

By Kirk Byers

In Part1 of this blog series, I demonstrated the basics of using Ansible for network configuration templating. In Part2, I expanded upon this system to create full configuration files including using conditionals. In this article, I am going to generalize the system and show you how to: 1)use different templates for a single role, 2)create a template hierarchy, and 3)use different roles.

As a quick reminder, there are three parts to this system—1)the tasks file (tasks/main.yml), 2)the vars file (vars/main.yml), and 3)the template file (currently, templates/router.j2). These files are all organized under an Ansible role (in my example, ./RTR-TEMPLATE/roles/router).

Python and SNMP Introduction

By Kirk Byers

In this article, I briefly introduce Python and SNMP using the pysnmp library. I assume that you already have some knowledge on SNMP including MIBs and OIDs. If not, you should be able to find this information fairly easily on the Internet. One resource that I found particularly helpful was the Cisco SNMP Object Navigator.

In order to get started, you need to install the PySNMP library. For context, I am testing on an AWS AMI server (Fedora/RedHat based).

Python Book Recommendations for Beginners

By Kirk Byers

You have decided to learn Python, but which Python book should you read? I have combed through a bunch of the beginner Python books looking for good choices.

Here are my reviews and recommendations; hopefully; this will save you some time and effort. A few disclaimers, these reviews are assuming the context of a beginner—either someone totally new to programming or a relatively inexperienced programmer that is new to Python. Consequently, while a certain book might be very good for an advanced programmer, it likely would be awful for a beginner.

Why do we still do so much manually?

By Kirk Byers

A common theme that I have heard and read recently is that network engineers are a significant obstacle to getting things done (or in less polite terms that us "CLI-jockeys" stink and it takes us way too long to configure a stupid VLAN). Bob McCouch talks about part of this issue in a recent blog post, "Those Slow Poke Network Engineers". In part of this article Bob states:

The lack of automation and tools force very manual workflows compared to virtual server technologies that basically instantiate a new server in seconds. This is a legitimate gripe considering the impact of server virtualization in terms of new application provisioning.