How to get GNS3 running on macOS Big Sur

Install GNS3 GUI

Published in

WXIT

5 min readDec 22, 2020

Download the GNS3 mac installer from the GNS3 website https://www.gns3.com/software/download. You will need to create a free account if you don’t already have one.

Open the dmg, and then drag the GNS3 icon to the Applications folder.

Install Wireshark

Download the Wireshark mac installer from the Wireshark website https://www.wireshark.org/download.html

Open the dmg, drag the Wireshark icon to the Applications folder. If you are only using Wireshark within GNS3, you do not need to run the ChmodBPF.pkg installer.

Set Console Applicaition

By default, GNS3 will use the macOS Terminal application for console connections, but this won’t work as Apple has removed Telnet from macOS.

Open GNS3, and from the menu bar, select Preferences. On the General preferences page, select the Console applications tab.

Click the Edit button, then select the console application you have installed on your Mac from the dropdown.

GNS Console Settings — GNS3 Console Settings

Install VNC Client

The built-in macOS VNC client (Apple Screen Sharing) has issues working with GNS3.

Download the free Lite version of Royal TSX https://royalapps.com/ts/mac/download

Open Royal TSX, and from the menu bar, select Plugins. Install the VNC plugin.

Open GNS3, and from the menu bar, select Preferences. On the General preferences page, select the VNC tab.

Click the Edit button, then select Royal TSX from the dropdown.

Test basic functionality

Before we install the GNS3 VM, we should test the basic functionality is working.

Create the following topology with two virtual PCs and a switch, connect them together, and click the play button to start all devices.

Click the console connect to all nodes button, and your console application should open with connections to both virtual PCs.

Set an IP address on both virtual PC’s

PC1> ip 192.168.1.1
Checking for duplicate address...
PC1 : 192.168.1.1 255.255.255.0PC2> ip 192.168.1.2
Checking for duplicate address...
PC1 : 192.168.1.2 255.255.255.0f

Click on one of the links and select start capture, then click ok.

Ping one of the PC’s from the other PC.

PC2> ping 192.168.1.1
84 bytes from 192.168.1.1 icmp_seq=1 ttl=64 time=0.306 ms
84 bytes from 192.168.1.1 icmp_seq=2 ttl=64 time=0.398 ms
84 bytes from 192.168.1.1 icmp_seq=3 ttl=64 time=0.574 ms

Wireshark should have opened automatically, and the ping packets displayed.

Now we have confirmed the basic functionality is working, and we can set up the GNS3 VM to allow more advanced devices to be used.

Install VirtualBox

Download VirtualBox from https://www.virtualbox.org/wiki/Downloads

Run the setup to install VirtualBox. Once the install wizard has finished, open the system preferences app, on the Security and Privacy section, click the Allow button, and reboot your Mac.

Open VirtualBox, click on Tools, and select Network.

Create a new network and enable DHCP

VirtualBox Network Settings — VirtualBox Networks Settings

Download the GNS3 VM image for VirtualBox from the GNS3 website https://www.gns3.com/software/download-vm

Double click the GNS3 VM.ovf file to import the VM into VirtualBox.

Edit the network settings for the VM. Check the first adapter is set to Host-only and connected to the correct network. The second adapter should be set to NAT.

Power on the VM and open GNS3 without opening a project. From the menu bar, select Preferences.

On the Server page, change the Host binding to the IP from the virtual network.

On the GNS3 VM page, Enable the VM and select the VM name from the dropdown.

The VM should then show as running in the servers list.

You can now add devices to your topology that require the GNS3 VM, for example, the Docker Guest.

Install Cisco device images

We can now install the Cisco virtual devices images for routers and switches.

Click on New template at the bottom of the device list. Select Install an appliance on the GNS3 server.

Select Routers > Cisco IOSv or Switches > Cisco IOSvL2 depending on which image you are installing. Then click the Install button. Select Install an appliance on the GNS3 VM and click Next. Leave the Qemu dropdown on the default and click Next.

Select the version you want to install and click the Download button, it will take you to the Cisco website, you will need to log in with your Cisco account that has an active subscription and download the file. Click the Refresh button and it will change to ready to install, click the next button and then click finish.