GNS3 allows network engineers to model networks. Unlike network simulators, GNS3 uses real device images. The devices run on a hypervisor. Unraid is an easy to use NAS operating system based on Slackware that supports docker images and virtual machines.

We will be using Ubuntu 20.04 as the base of GNS3. Install it as you would normally install it. After or before installation, you will need to edit the Unraid XML file of VM to allow nested VMs.

* In Unraid, go to the “VM” tab.

* Click the VM icon and then click on “Edit”.

* On the upper right of the page, click on the switch , to switch to XML view.

* In the cpu mode='host-passthrough' area, add <feature policy='require' name='vmx'/>

Install GNS3. All commands need to be run as root or sudo. You can install GNS3 with OpenVPN if you plan to access it from the Internet. However, we will only be accessing GNS3 through the local network.

cd /tmp
curl https://raw.githubusercontent.com/GNS3/gns3-server/master/scripts/remote-install.sh > gns3-remote-install.sh
bash gns3-remote-install.sh --with-iou --with-i386-repository

This will take some time to finish.

After the install finishes, edit /etc/gns3/gns3_server.conf to change the default IP the GNS3 listens on. By default, it listens on the IP that OpenVPN would normally be on.

Edit the host line to the IP of your server.

Restart the GNS3 service.

systemctl restart gns3

You should now have a working GNS3 installation. You will now need to add your server as a remote server for your GNS3 installation.