I found myself wanting to use GNS3 in class. The students should work in groups. I didn't want to loose to much time providing 1st level support to every student to get GNS3 up and running. Besides I had no garantee that the laptops they owned had enough processing power and RAM.

The decision: Build a proxmox cluster and automatically deploy the virtual machines containing GNS3.

Special requirement: The students should be able to communicate with the GNS3 lab like the would if they connected their PC with a ethernet cable. Thats why I used OpenVPN and added a virtual bridge to every instance.

• cloudinit using datasource NoCloud
• proxmox
• GNS3
• A GNS3 installation script
• A 10 year old VLAN able gigabit switch
• MikroTik Router
• ubuntu cloud image

• Assemble a bunch of old servers, wire them up and install proxmox on it
• Enable nested virtualization
• Network configuration (added nfs vlan, lab vlan and cluster vlan)
• Put all the servers in one cluster
• Set up vm with http server so that it can be used with nocloud-net
• Create necessary cloudinit files and install scripts (see /var/www/html)
  • networking.sh => Some network adjustments and bug fixes
  • gns3-remote-install.sh => original GNS3 install script adjusted for my needs
• Write script to automatically build VMs in proxmox
• Add some dirty PHP with some features
• Fix scripts until they work
• Deploy all machines for my students

• Preliminary: The vm-create-scripts and the ubuntu cloud image are stored in a nfs that is connected to all proxmox nodes
• run ./create.sh VMID N times on the server (n beeing the number of vms to run on that physical machine)
• Start the VM
• Get the keys from the MASTERNODE

• Basically a HTTP server with all the preliminary files the VMs need to install GNS3 and OpenVPN
• Debian GNU/Linux 10 Server with packages:
  • apt install apache2-utils apache2 php php-mysql libapache2-mod-php
• For WebDAV we need SSL:
  • openssl req -x509 -nodes -days 3650 -newkey rsa:4096 -keyout /etc/ssl/private/apache-selfsigned.key -out /etc/ssl/certs/apache-selfsigned.crt
• apache2:
  • a2enmod ssl
  • a2enmod dav
  • a2enmod dav_fs
• WebDAV activated for faster development
• VM loads files used by cloudinit

• The user-data script calls the networking.sh script. When this script is finished it makes a POST request to the MASTERNODE submitting the ovpn configuration for the client.

• No, you'll have to adjust it to your infrastructre.

• Plan and deploy your cluster (hardware, networking)
• At least replace the following placeholders
  • MASTERNODE
  • ADD_YOUR_KEY_HERE
  • ADD_YOUR_PASSWOR_HERE
• Set up vm with http and put all files in that folder
• Prepary one GNS3 lab with images, but the hole image folder into a tar.gz and put in /var/www/html/images on the MASTERNODE.

23.02.2021