Install Azure CLI on your Android Phone

I installed the Azure CLI in the Termux app on my Android phone. This post describes all the steps required to successfully run Azure CLI on most Android phones.

Installing Azure CLI on Termux on your Android phone is an alternative to using Azure Cloud Shell on Chrome or Firefox, or to using the Cloud Shell feature on the Azure mobile app. It’s also a cool thing to try.

This post is based on the excellent work done by Matthew Emes, who wrote a blog post about installing Azure CLI on a Chromebook. Matthew’s procedure got me started, but I had to modify it to make Azure CLI work in Termux on my Android phone. Also, Azure CLI has changed since Matthew wrote about it and some of his steps, while they still work, are no longer necessary.

Termux

Install Termux on your Android phone. Termux is a terminal emulator and Linux environment that runs on most Android devices with no rooting or setup required. You can use Termux as a terminal emulator to manage remote systems and it will run a large number of Linux utilities and programming languages directly on your phone. Install it from the Google Continue reading

Run a script on virtual machines when the host is shut down

I want to show you how to configure a host server so, when it is shut down, it executes a script that runs commands on any running virtual machines before the host tries to stop them. I will configure the host server to wait until the script completes configuring the virtual machines before continuing with the shutdown process, shutting down the virtual machines, and eventually powering off.

I had to learn how Systemd service unit configuration files work and some more details about how Libvirt is configured in different Linux distributions. Read on to see the solution, plus some details about how to test the solution in Ubuntu and CentOS.

Solution Summary

Create a new Systemd service named graceful-shutdown that runs a script when the host system shuts down, but before Libvirt shuts down any virtual machines. Ensure that the libvirt-guests service is already started and enabled, and is configured appropriately.

The graceful-shutdown.service unit configuration file

Create a new Systemd unit configuration file named graceful-shutdown.service and save it in the directory, /etc/systemd/system, where it is advised you put custom configuration files.

For example:

# vi /etc/systemd/system/graceful-shutdown.service

Enter the following text into the file, then save it:

 Continue reading

Video chat about NRE Labs

Yesterday, I participated in a screen-cast with Derick Winkworth, aka @CloudToad, to discuss my blog posts about installing NRE Labs Antidote network emulator on your PC and creating lessons for NRE Labs. We also covered some general points like contributing to communities, how to get started blogging about technical topics, and more. Check it out, below:

This video, and other NRE Labs videos are available on YouTube. Also, the NRE Labs team runs a live screen-cast every Monday at 1:00 PM using the Discord app. Join the NRE Labs Discord channel and engage in the discussion.

Create lab lessons for the NRE Labs Antidote network emulator

The Antidote network emulator, part of the Network Reliability Engineering project, offers a web interface that presents network emulation scenarios to users as documented lessons. Each lesson is presented in a window running Jupyter Notebooks and contains commands that the user can click on to run them on the virtual nodes in the network emulation scenario.

The NRE Labs developers intend for Antidote to be used as an educational tool. Its lesson-focused user interface supports students’ learning progress. This post is a tutorial showing how to create and test two simple, but different, Antidote lessons.

Lab documentation

At the time I wrote this post, the Antidote documentation does not provide enough practical information about how to create new Antidote labs. However, useful information is spread around in a few different locations, which I list below:

• Read the documentation about Lesson Endpoints
• The NRE Labs blog and videos on the NRE Labs Community Resources page provide some useful information about building labs for Antidote
• The Tips and FAQs Page that includes useful information about building lessons
• Read the post on the NRE Labs blog about how NRE Labs implements curriculum as code
• You can also reverse-engineer existing lab lessons
• Look Continue reading

Install the Antidote (NRE Labs) network emulator on a Linux system

Antidote is a network emulator combined with a presentation framework designed to create and deliver networking technology training. Its user interface operates in a web browser, including the terminals that students use to run commands on emulated network devices and servers.

Antidote is the engine that runs the Network Reliability Labs web site. Antidote is an open-source project, released under the Apache license. A standalone version of Antidote may be installed and run on your personal computer using the selfmedicate script. In this post, I will install Antidote on my Linux laptop and make a few changes that improve Antidote performance on my Linux system.

Antidote documentation

The Antidote documentation is being expanded regularly but, at the time I am writing this, the most helpful information is in the NRE Labs blog and in the videos produced by the developers. Most of these are accessible from the NRE Labs Community Resources page.

Also, Antidote is in active development and it is changing quickly as the developers create new features and content. Keep that in mind when following this blog post. Some things may already have changed about the way Antidote installs or operates.

Install prerequisite software

Antidote requires that you Continue reading

The Wistar network emulator

Wistar is an open-source network emulator originally developed by Juniper Networks and released under the Apache license. It simplifies the presentation of Juniper products on its graphical user interface by making the multiple VMs that make up each JunOS virtual router appear as one node in the network topology.

Wistar also supports Linux virtual machines and, interestingly, uses cloud-init to configure Linux routers from the Wistar user interface. Wistar also supports generic virtual appliances, in a basic way. In this post, I will install Wistar and use it to work through two examples using open source routers.

Wistar Documentation

The Wistar installation procedure is documented in the Wistar GitHib page. The Wistar user guide is available at the Read the Docs website and some unpublished chapters are available on GitHub. Juniper published a presentation about using Wistar. In addition, there are a few other other blog posts available about using Wistar and comparing Wistar to other network emulators.

• Wistar GitHub page: https://github.com/Juniper/wistar
• Wistar user guide: https://wistar.readthedocs.io/en/latest/

Wistar documentation is good enough to get started, but seems to be incomplete.

Install Wistar

I installed Wistar on my laptop computer running Ubuntu 18.04 LTS. I modified the Wistar Continue reading

Vrnetlab: Emulate networks using KVM and Docker

Vrnetlab, or VR Network Lab, is an open-source network emulator that runs virtual routers using KVM and Docker. It supports developers and network engineers who use continuous-integration processes for testing network provisioning changes. Researchers and engineers may also use the vrnetlab command line interface to create and modify network emulation labs in an interactive way. In this post, I review vrnetlab’s main features and show how to use it to create a simple network emulation scenario using open-source routers.

Vrnetlab implementation

Vrnetlab users create Docker images for each type of router that will run in their network. They package the router’s disk image together with KVM software, Python scripts, and any other resources required by the router into the Docker image. Vrnetlab uses KVM to create and run VMs based on router software images, and uses Docker to manage the networking between the network nodes.

Virtual nodes

Vrnetlab users create Docker images that incorporate the router’s qemu disk image, along with software packages such as qemu-kvm, and the other resources needed by the router, such as a launch script and license files. The new Docker image represents a “virtual router” that comes with all the software and Continue reading

Build a network emulator using Libvirt

I want to explore some of the network virtualization and emulation building blocks available on a Linux system. In this post, I create a simple network emulation scenario using Libvirt, the Qemu/KVM hypervisor, and Linux bridges to create and manage interconnected virtual machines on a host system.

Libvirt provides a command-line interface that hides the low-level virtualization and networking details, enabling one to easily create and manage virtual networking scenarios. It is already used as a basis for some existing network emulators, and other applications and tools. It is available in almost every Linux distribution.

The network emulation scenario

As you work through the examples in this post, you will create a very simple network topology which is intended to demonstrate the use of Libvirt and other virtualization tools to build a network emulator and is not intended to emulate a real-world network. However, once you understand its operation, you may use Libvirt to create large, complex network topologies intended to emulate real-world network scenarios.

The example I created for this post consists of three virtual machines serving as routers connected to each other in a ring topology. On each side of this emulated network, you will create Continue reading

Python: the seven simple things network engineers need to know

Are you like me? Are you a network engineer, or other professional, transitioning their skill set to include programming and automation? Does your programming experience experience come from a few programming courses you attended in college a long time ago? Then please read on because I created this Python guide for people like you and me.

In this guide, I explain the absolute minimum amount you need to learn about Python required to create useful programs. Follow this guide to get a very short, but functional, overview of Python programming in less than one hour.

When you begin using Python, there are a lot of topics you do not need to know so I omit them from this guide. However, I don’t want you to have to unlearn misconceptions later, when you become more experienced, so I include some Python concepts that other beginner guides might skip, such as the Python object model. This guide is “simple” but it is also “correct”.

Getting Started

In this guide, I will explore the seven fundamental topics you need to know to create useful programs almost immediately. These topics are:

1. The Python object model simplified
2. Defining objects
3. Core types
4. Statements
5. Simple programs
6. Modules
7. Continue reading

Create a nested virtual machine in a Microsoft Azure Linux VM

Microsoft Azure unofficially supports nested virtualization using KVM on Linux virtual machines, which makes it possible to build network emulation scenarios in the cloud using the same technologies you would use if you were using your own PC or a local server.

In this post, I will show you how to set up a Linux virtual machine in Microsoft Azure and then create a nested virtual machine inside the Azure virtual machine. This is a simple example, but you may use the same procedure as a starting point to create more complex network emulation scenarios using nested virtualization.

Prerequisites

To follow this tutorial, you need an Azure account. Microsoft offers a free-trial period that provides up to $300 in credits for up to 30 days. Creating a free trial account is easy: follow the instructions at: https://azure.microsoft.com/free.

If you have not used MS Azure before, I recommend the free training offered on their web site. The first course you should take is the beginner-level Azure Administrator course, which demonstrates all the basic topics you will need to understands when managing virtual machines in Azure.

In this tutorial, I will use the Azure CLI to create and manage Continue reading

Network Labs Using Nested Virtualization in the Cloud

Many open-source network simulation and emulation tools use full virtualization technologies like VMware, QEMU/KVM, or VirtualBox. These technologies require hardware support for virtualization such as Intel’s VT-x and AMD’s AMD-V. To gain direct access to this hardware support, researchers usually run network emulation test beds on their own PCs or servers but could not take advantage of the inexpensive and flexible computing services offered by cloud providers like Amazon EC2, Google Compute Engine, or Microsoft Azure.

By August 2017, most of the major cloud service providers announced support for nested virtualization. In the cloud context, Nested Virtualization is an advanced feature aimed at enterprises, but it is also very useful for building network emulation test beds. I’ve written about nested virtualization for servers before but, until recently, I was limited to running nested virtual machines on my own PC. Now that the major cloud providers support nested virtualization, I can build more complex network emulation scenarios using cloud servers.

This post will discuss the cloud service providers that support nested virtualization and how this feature supports open source networking simulation and emulation in the cloud.

Cloud service providers support for nested virtualization

The cloud service providers Continue reading

Enable nested virtualization on Google Cloud

Google Cloud Platform introduced nested virtualization support in September 2017. Nested virtualization is especially interesting to network emulation research since it allow users to run unmodified versions of popular network emulation tools like GNS3, EVE-NG, and Cloonix on a cloud instance.

Google Cloud supports nested virtualization using the KVM hypervisor on Linux instances. It does not support other hypervisors like VMware ESX or Xen, and it does not support nested virtualization for Windows instances.

In this post, I show how I set up nested virtualization in Google Cloud and I test the performance of nested virtual machines running on a Google Cloud VM instance.

Create Google Cloud account

Sign up for a free trial on Google Cloud. Google offers a generous three hundred dollar credit that is valid for a period of one year. So you pay nothing until either you have consumed $300 worth of services or one year has passed. I have been hacking on Google cloud for one month, using relatively large VMs, and I have consumed only 25% of my credits.

If you already use Google services like G-mail, then you already have a Google account and adding Google Cloud to your account is easy. Continue reading

Install and run the Cloonix network emulator on Packet.net

This tutorial shows how to set up the Cloonix network emulator on a Packet.net server. It builds on top of my previous post about how to set up a virtualization server on Packet.net. Now, I focus on a specific case: setting up the Cloonix network emulator on the virtualization server. You should read my previous post before reading this one.

Running Cloonix on a remote server enables users to work with more complex network emulation scenarios than would be possible on a standard laptop computer. For example. Cloonix recently added a feature which allows users to run Cisco router images in a Cloonix network emulation scenario. Cisco router images require a large amount of computer resources so I cannot run more than a few on my personal laptop computer. If I use a remote Packet server, I could run dozens of Cisco images in a network emulation scenario if I wanted to.

In this post, I will set up a Cloonix network emulation server on Packet.net so it can be started, stopped, and restarted relatively quickly.

Table of Contents

1. Cloonix v37 overview
2. Packet.net overview
3. Tutorial summary
4. Start a server and attach storage
5. Load Files onto Block Continue reading

Set up a dedicated virtualization server on Packet.net

Packet is a hardware-as-a-service vendor that provides dedicated servers on demand at very low cost. For me and my readers, Packet offers a solution to the problem of using cloud services to run complex network emulation scenarios that require hardware-level support for virtualization. Packet users may access powerful servers that empower them to perform activities they could not run on a normal personal computer.

In this post, I will describe the procedure to set up an on-demand bare metal server and to create and maintain persistent data storage for applications. I will describe a generic procedure that can be applied to any application and that works for users who access Packet services from a laptop computer running any of the common operating systems: Windows, Mac, and Linux. In a future post, I will describe how I run network emulation scenarios on a Packet server.

Table of Contents

1. Packet.net
   1. Controlling costs when using bare metal servers
   2. Create a Packet account and Login
   3. Create a project
2. Generate SSH Keys
   1. Windows
   2. Mac
   3. Linux
   4. Copy public key to Packet.net
3. Deploy a Server
4. SSH Server on local machine
   1. Windows
   2. Mac
   3. Linux
5. Set up the remote server
   1. Test X11 forwarding
6. Create block storage
   1. Create Continue reading

Install the CORE Network Emulator from source code

To install the CORE network emulator in recently released Linux distributions, including Ubuntu 16.04 and later, you must install it from source code. There is a bug in CORE that prevents Quagga from starting its routing daemons in newer Linux distributions that is fixed in the latest version of the source code. However, the fix is not in the pre-built CORE packages available on the CORE web site, nor in the Ubuntu repository.

To further create problems, the CORE web site contains old versions of source code and does not point to the latest version of CORE on Github.

Also, the Ubuntu maintainers will remove CORE packages from the Ubuntu repository in the near future because CORE allows unprivileged users to access root privileges, which creates a security problem if CORE is run on a computer used by more than one person.

In this post, I provide a detailed procedure to install CORE from the source code on Github, and to set up your system to run network experiments using the CORE network emulator.

Install CORE from Github

The latest version of CORE is available on Github. To install CORE, first install some prerequisite packages that allow you to Continue reading

Netdev 2.1 conference report

I attended the Netdev 2.1 Conference in Montreal from April 6 to 8. Netdev is a community-driven conference mainly for Linux networking developers and developers whose applications rely on code in the Linux kernel networking subsystem. It focuses very tightly on Linux kernel networking and on how packets are handled through the Linux kernel as they pass between network interfaces and applications running in user space.

In this post, I write about the three-day conference and I offer some commentary on the talks and workshops I attended. I grouped my comments in categories based on my interpretation of each talk’s primary topic. The actual order in which these topics were presented is available in the Netdev 2.1 schedule. The slides from the talks, workshops, and keynotes are posted under each session on the Netdev web site. Videos of the talks are available on the netdevconf Youtube channel.

Keynotes

Each day at the Netdev conference featured a keynote by a prominent member of the Linux networking community. Two of the keynotes covered higher-level views of Linux in the network in the enterprise, cloud, and the Internet of things. The other keynote covered details of the new eXpress Data Path Continue reading

Build a custom Linux Router image for UNetLab and EVE-NG network emulators

In their default configuration, the UNetLab and EVE-NG network emulators support Linux nodes running bootable CDROM or DVDROM images that offer a graphical user interface accessible via VNC.

We may add new Linux node types to both UNetLab and EVE-NG by building Linux VM images and creating custom templates. To support Linux networking emulation scenarios, we will build a linux router image that boots from a virtual hard disk, can be accessed via Telnet to simplify configuration and management, and that has a persistent file system onto which we can install software and modify configuration files.

In this post, we will show how to build a Linux router image and create a custom Linux router template that can be used in UNetLab or EVE-NG.

Add a custom Linux server image to UNetLab or EVE-NG by following the procedure below:

1. Install a Linux server on a virtual machine on your host computer
2. Start the new virtual machine and configure it so it is accessible via Telnet after it is moved into UNetLAb or EVE-NG:
   • Install and enable Telnet
   • Add a serial interface
   • Add networking software
   • Stop the virtual machine
3. Copy the new virtual machine’s disk image to the UNetLab or EVE-NG Continue reading

How to set up the EVE-NG network emulator on a Linux system

EVE-NG is a graphical network emulator that supports both commercial and open-source router images. It’s graphical user interface runs in a web browser. EVE-NG runs in a virtual machine so it can be set up Windows, Mac OS, or Linux computers.

In this post, I will show how to set up an EVE-NG virtual machine on an Ubuntu Linux system. I’ll show the basic steps to creating and running a simple lab consisting of emulated Linux nodes.

To support more complex labs using open-source routers and other open-source network appliances in EVE-NG, we need to create custom templates and build router images specifically for use in EVE-NG. I will cover these topics in a future post. In this post, we’ll focus only on getting an EVE-NG virtual machine set up and running on a Linux system.

EVE-NG Overview

EVE-NG is a clientless network emulator that provides a user interface via a browser. Users may create network nodes from a library of templates, connect them together, and configure them. Advanced users or administrators may add software images to the library and build custom templates to support almost any network scenario.

EVE-NG supports pre-configured multiple hypervisors on one virtual machine. It runs Continue reading

DNS and BIND demonstration using the Cloonix network emulator

The Domain Name System (DNS) is a fundamental Internet technology. Network emulators like Cloonix offer a way for researchers and students to experiment with the DNS protocol and with the various open-source implementations of DNS, such as BIND.

In this post, I will install Cloonix from the Github source code repository. I will run the Cloonix DNS demo script to create a simple DNS scenario and then run some experiments with DNS. Along the way, I will demonstrate some of the new Cloonix version 33 features.

Cloonix version 33

In this demonstration, I am using Cloonix version 33. I last used Cloonix when it was at version 29 and version 33 offers some significant changes and improvements. Compared to version 29, the major changes in version 33 are:

• The Cloonix source code is now hosted on Github
• The cloonix-ctrl commands have been renamed to cloonix-cli
• The Cloonix lan object is now much simpler
• Cloonix adds a simple GUI called cloonix_zor for managing Cloonix servers that have been started
• The nat object replaces the cloonix slirp LAN
• New demo scripts have been added. One of which, the DNS demo script, we will use in this demonstration

Using Cloonix version 33

If Continue reading

OFNet SDN network emulator

OFNet is a new software-defined network (SDN) emulator that offers functionality similar to the Mininet network emulator and adds some useful tools for generating traffic and monitoring OpenFlow messages and evaluating SDN controller performance.

OFNet is an open-source project that is distributed as a virtual machine (VM) image. The OFNet source code is available in the OFNet VM’s filesystem. In this post, we will use the OFNet VM provided by the OFNet developer to run SDN emulation scenarios in OFNet.

The OFNet Virtual Machine

The OFNet VM image is packaged as an OVA file which can be imported into most virtual machine managers. In this case, we are using VirtualBox. You may download the OFNet VM from this link.

The OFNet VM contains a Linux system running Ubuntu 12.04 and has the VirtualBox extensions installed.

Create a new virtual machine using the OFNet VM image, start up the VM and log in. After logging in, review the available OFNet documentation and install Wireshark.

Install the OFNet VM in VirtualBox

Import the OFNet.ova file into VirtualBox. Use the File → Import Appliance VirtualBx menu command or press <Ctrl-I>. Navigate to the location where you saved the OFNet.ova file Continue reading