Networking

GNS3 Beta Packet Capture between QEMU devices

One of the cool things that you can do with GNS3 is packet captures between devices.  However, if you are using QEMU (Quick Emulator) Cisco image devices, the current stable release of GNS3 does not support packet captures with QEMU devices.  However, only the current Beta release versions of GNS3 support packet captures with QEMU. Let’s take a look at the GNS3 Beta packet capture between QEMU devices.

GNS3 Beta Packet Capture between QEMU devices

First off, you need to go to Github and grab the latest version of the Beta release for GNS3.  You can find that here:  https://github.com/GNS3/gns3-gui/releases

We will pull down a couple of packages from here – The all in one installer for Windows, and the GNS3 VM for ESXi.

gns3beta1a

Installation

The GNS3 all in one installer is a simple “Next, Next, finish” installer that is painless.  You will have options to install the requirements such as Winpcap, etc.  Wireshark is part of the installer as well so for packet capturing you should have everything you need in the default installer.

gns3beta01b

GNS3 VM

Installation of the GNS3 VM for ESXi is equally as painless.  I have a write up here on how to set this up in ESXi.  As a short description, it involves importing the OVA appliance and settings your network settings.  After the initial configuration, you just need to import your “appliance” from the GNS3 marketplace such as the IOSv appliance and the IOSvL2 appliance.  These are quick configuration templates that make it possible to quickly and easily import your VIRL bases IOSv and IOSvL2 images.

Running a Packet Capture

After you have GNS3 installed as well as the GNS3 VM along with images to play around with, you can start packet capturing.  In order to take a packet capture between QEMU VMs (only possible at this point in 2.0 beta’s), you simply right click on your link and start capture.

gns3beta02

gns3beta03

gns3beta04

Thoughts

The packet capture in GNS3 is such a great learning tool that allows you to see at a very low level the packets coming across the simulated wire as they would in a real production network.  As mentioned, this is currently only available in the beta releases for QEMU as you receive an error message when trying to packet capture between QEMU in the current stable release.

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Brandon Lee

Brandon Lee is the Senior Writer, Engineer and owner at Virtualizationhowto.com and has over two decades of experience in Information Technology. Having worked for numerous Fortune 500 companies as well as in various industries, Brandon has extensive experience in various IT segments and is a strong advocate for open source technologies. Brandon holds many industry certifications, loves the outdoors and spending time with family.

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