Archives For tools

When writing a blog post about a technical topic, I often capture a lot of screen shots that I need to edit before adding them to my blog article. Usually I want to add a border around each image and I sometimes want to reduce the size of images that are too large. I want to do this quickly and easily so I use ImageMagick, an open-source command line image editor.


ImageMagick is a powerful image manipulation tool with an intimidatingly large set of options and subcommands. However, most bloggers will use only a few simple options. In this post, I will show how to install and use ImageMagick to perform the simple image conversions bloggers typically need. I will show how this can be done on each of the major operating systems: Linux, Windows, and Mac OS X.

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This article describes my first experience with the cloonix open-source network simulator. I installed cloonix on ubuntu 12.04 and tested it by running the demonstration script provided with the cloonix package. The demonstration script sets up a simulated OSPF network and runs HTTP traffic between two virtual computers attached to that network.

cloonix network simulator

cloonix network simulator running on ubuntu 12.04

The cloonix package provides modified versions of networking tools and virtual machine management tools, so one does not need to install a lot of supporting software. The developers also provide filesystems for Linux distributions such as Debian and Vyatta (a Linux router) that can be used in the simulations. More details about what makes cloonix special are available in the online cloonix documentation.

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Debian 8.2 Running

In this article, we will review the procedures required to install Debian Linux in a virtual machine managed by the VirtualBox application. A summary of the procedures is listed below:

  • Download the Debian install DVD.
  • Create a virtual machine using the VirtualBox application.
  • Boot the virtual machine from the DVD image we downloaded
  • Install the Debian Linux operating system on the virtual machine.

We will install Debian Linux because it is the version of Linux that is used by most of the researchers who have developed the network simulation tools we wish to investigate. Also, Debian is a conservative Linux distribution so we can be fairly confident that if we run into issues, we will not need to debug the operating system.

Here is the procedure we followed:

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Why use a Virtual Machine?

September 30, 2012


I am building a virtual machine that will run the open-source network simulation tools that I want to research. There are good reasons to use a virtual machine for these experiments, even if software running inside a virtual machine may run slightly slower than software running on a native host. Below, I list the benefits of using a virtual machine for this research project.

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NetKit test drive

August 25, 2012


Let’s look at the NetKit network simulator first. NetKit offers some useful prepared labs and provides the NetKit files already installed on a Knoppix LiveDVD. These assets make it easy to try out Netkit.

To take a first look at NetKit, we will load the LiveDVD into a VirtualBox virtual machine running on our computer and follow the steps below to run a simple lab using NetKit.

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NOTE updated February 26, 2013: This post contains old information. I created a page that lists all the open-source network simulators listed in the post below. I will keep the page up-to-date. Please see the List of Open-Source Network Simulators page.

I’ve searched around and found a long list of potential solutions for an open-source network simulator. I listed the ones below that I think will fit my requirements. This list is based on only a quick look at each tool so I my comments below may not fully reflect the utility of each tool. I will have a detailed look at more than a few of these tools later.

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