GNS3 Server on Ubuntu 24.04 LTS

GNS3 is the widely used open source network emulation platform for designing, building and testing network topologies without physical hardware. It runs virtual labs made of emulated Cisco routers, Docker containers, QEMU virtual machines and lightweight virtual PCs, wired together into topologies you can start, stop and inspect. It is used for network certification study, for validating designs and change plans before they reach production, and for building reproducible lab environments for teams. This image delivers the GNS3 server, the headless controller and compute engine that runs the labs, fully installed and secured.

Secure by default

An unprotected GNS3 interface lets anyone who can reach it create and run containers and virtual machines on the host, so an open one is effectively an open door to the server. This image closes it at two independent layers using a single credential. The server listens only on the local loopback interface with its own authentication switched on, and an nginx reverse proxy terminates TLS and enforces authentication on every request. A unique credential is generated on each virtual machine's first boot and applied to both layers. Only a one way hash is stored on the server, the plain password is placed in a root only file, and nothing usable is baked into the image, so no two deployments share a credential. Device consoles are bound to the loopback interface rather than exposed to the network, and are reached through a secure tunnel.

Hardened and ready on first boot

• The complete emulation stack is installed and version pinned: the Dynamips router emulator, the ubridge network bridge, the VPCS virtual host emulator, QEMU and Docker, all wired to the server.
• A ready to run container appliance template is included, so you can start a real emulated node immediately without downloading anything first.
• The interface is served over HTTPS on port 443 with a certificate regenerated per virtual machine on first boot; port 80 redirects to HTTPS and an unauthenticated health endpoint is provided for load balancer probes.
• The service runs as an unprivileged system user under systemd for automatic restarts and clean logging.

Choosing a virtual machine size

Dynamips, Docker and virtual PC nodes run on any size. QEMU virtual machine nodes are hardware accelerated through KVM, which on Azure requires nested virtualisation: use Standard_D2s_v3 or larger, which is the recommended size for this image. The deployment guide explains the difference in full.

Why cloudimg

cloudimg delivers GNS3 Server fully patched on a hardened Ubuntu 24.04 LTS base, running on first boot, with no shared credentials and no emulator setup to do yourself. Every image passes an automated verification gate and is backed by 24/7 support with a guaranteed 24 hour response SLA.

Licensing

GNS3 is open source software distributed under the GNU General Public License v3.0, and is free. The cloudimg charge covers packaging, hardening, security patching, image maintenance and 24/7 support. A step by step deployment guide is provided.