Networx

A browser-based network emulator for teaching computer networking concepts at GCSE and A Level (OCR specifications J277 and H446).

Live demo →

What it does

Networx lets you build virtual networks by dragging hardware components onto a canvas and connecting them with wired or wireless links. Once built, you can:

• Run terminal commands on PCs, laptops, and servers — ping, traceroute, ipconfig, nslookup, curl, ssh, and more
• Browse the web — a built-in browser on PC/Laptop/Server nodes renders pages served by Web Server nodes, resolves hostnames via local DNS, and simulates internet access through a Cloud node
• SSH between nodes — ssh <ip> opens a persistent session; all subsequent commands run as the remote device until you type exit
• Assign IPs with DHCP — routers run a DHCP server; clients request leases with dhclient (Linux) or ipconfig /renew (Windows), animating the full four-way handshake
• Configure DNS records — DNS Server nodes hold A records that resolve hostnames across the network
• Ping domain names — ping google.com resolves via DNS and routes through the internet node
• Inspect switch MAC tables — tables populate as traffic flows, showing which MAC address was learned on which port
• Configure routers — add static routing table entries
• Set firewall rules — allow/deny by protocol, port, and IP
• Configure wireless access points — SSID, WPA key, 2.4/5 GHz band
• Load preset scenarios — five built-in topologies covering key exam topics
• Save and share — export your network as a .json file and import it elsewhere

Preset scenarios

Scenario	Covers
Star Topology (LAN)	Switch MAC tables, LAN addressing, ping
Home Network	NAT, router, WAP, wired + wireless clients
School Network	Firewall rules, network segmentation, servers
Client-Server Model	DNS resolution, HTTP, nslookup, curl
Mesh / WAN Topology	Redundant paths, inter-site routing, internet backbone

Curriculum links

• OCR GCSE Computer Science J277 — Networks (1.3): protocols, hardware, topologies, internet, security
• OCR A Level Computer Science H446 — Communication and networking (1.3): IP, TCP/IP stack, packet switching, hardware, client-server

Spec links:

• GCSE J277
• A Level H446

Running locally

npm install
npm run dev

Requires Node 18+.

Tech stack

• React + TypeScript
• React Flow (@xyflow/react) — canvas and graph rendering
• Zustand — state management
• Tailwind CSS — styling
• Lucide React — icons
• Vite — build tool

License

MIT — see LICENSE.