GNS3 vs Kathará

GNS3 is free, open-source software for emulating, configuring, testing, and troubleshooting virtual and real networks. Its graphical client works with a virtual machine, and servers can run locally or remotely. Users can combine emulated devices running actual images with simulated devices, including a built-in layer 2 switch. It supports appliances from vendors such as Cisco, Brocade, Cumulus Linux, and HPE, as well as Docker, QEMU-based appliances, VMware, VirtualBox, Hyper-V, and connections to real networks. The GNS3 Marketplace offers preconfigured appliance templates with recommended settings. It runs on Windows, macOS, and Linux; documentation recommends the GNS3 VM for most Windows and macOS setups and complex topologies. Users must supply their own Cisco IOS images. There are no monthly or yearly license fees, and device capacity depends in practice on the host computer’s CPU and memory. GNS3 is used for networking education, certification practice, proofs of concept, demonstrations, and interoperability testing. A server has no authentication enabled by default and should be restricted at the network level.

Kathará is a free, open-source system for emulating networks in interactive lessons, demos, production-network sandbox tests, and protocol development. It represents network devices with containers connected through virtual Layer-2 LANs, and scenarios can use Docker or Kubernetes as their virtualization backend. Built-in images include Quagga, FRRouting, Bind, P4, and OpenVSwitch; users can also supply their own container images. A Python package exposes APIs for custom code. Kathará supports Linux, macOS on Intel or Apple Silicon, and Windows 10 and 11. Debian and Ubuntu installations are available through apt, with precompiled packages for other listed distributions. Settings cover IPv6, terminal behavior, volume mounts, and remote Docker or Kubernetes connections. The software depends on Docker by default, and rootless Docker and Podman are unsupported. The project lists version 3.8.3 as covered by security patches. It is free, with a listed price of free.