NCAT

A networking and cybersecurity lab inside Minecraft.

Requires Minecraft 1.20.1, Forge 47.1.65+, Java 17 and MCEF 2.1.1.

What it is

NCAT Minecraft turns Minecraft into a networking and cybersecurity lab. In-game screens run a real Chromium browser. From them you can open SSH and SFTP sessions, a local terminal, remote desktop over RDP or VNC, and a proxy that pauses and edits HTTP requests in real time.

The network is physical too: data cables, RJ45 ports, VLAN-capable switches, racks full of modules and a workstation that reaches everything connected to it. The mod is built for classes and authorized labs, where students build the infrastructure by hand and watch the traffic flow.

Features

Screens

Each screen is a block that joins its neighbours into a larger monitor. The frame colour tells you what it does.

Physical network

• Data cable, RJ45 port and port installer: any screen can get network ports. Cables hang with weight, route around blocks along the floor and take waypoints from the cable adjuster.
• 8-port unmanaged switch and 8-port managed switch with VLANs, disabled ports and port isolation. The managed switch is configured from the configuration tablet, wired to the switch console with the serial cable.
• USB cable and USB port to wire keyboards to screens.
• Activity LEDs on every port, blinking with real traffic.

Rack

• 12U floor rack, 18U extension (stacks up to 6 sections) and 6U wall rack.
• Modules: browser, SSH, SFTP, log, developer tools, terminal, remote connection, proxy, switch and managed switch.
• Glass door, per-module power, extra network ports and cables dressed through an inner side channel.
• Modules have no screen of their own: their content shows up on the workstation connected to the network.

Tools and accessories

• Linking tool: ties a keyboard to a screen, or an analysis screen (log, developer tools, proxy, SFTP) to its source screen.
• Screen configurator: resolution, rotation, owner, friends and permissions.
• Laser pointer, log laser inspector and request tablet.

Furniture

Gaming chair (you can sit on it), toilet, water cooler with jug and disposable cup, digital clocks (world time and local time), rubber duck and a Wi-Fi adapter.

Requirements

RDP only works on Windows x64 and Linux x64. The other screens depend on MCEF support for your platform. Every screen runs a Chromium instance, so give Minecraft at least 4 GB of memory.

Download and installation

1. Install Forge 1.20.1, version 47.1.65 or newer, from the official Forge site.
2. Download NCAT Network Lab from the Files tab. Use ncat_minecraft-<version>.jar. If you see a file ending in -slim.jar, do not use it: it lacks the SSH and VNC libraries.
3. Download MCEF 2.1.1 for Forge 1.20.1 from Modrinth or CurseForge.
4. Put both files in the Minecraft mods folder:
   • Windows: %APPDATA%\.minecraft\mods
   • Linux: ~/.minecraft/mods
5. Start the game with the Forge profile. On first launch MCEF downloads the Chromium binaries into mods/mcef-libraries, which can take a few minutes.

Dedicated server: install NCAT Minecraft and MCEF in the mods folder of the server and of every player.

Verify the download: each release ships a SHA256SUMS.txt file. Compare it with the hash of your file:

sha256sum ncat_minecraft-*.jar

Get-FileHash .\ncat_minecraft-*.jar -Algorithm SHA256

Getting started

1. Build a screen

Place screen blocks side by side to form a rectangle at least 2 blocks wide or tall (the default maximum is 16 × 16). Right-click any block with an empty hand: the screen turns on.

If a block is broken and placed back within 10 minutes, the screen comes back with the same settings and ports.

2. Type

• Browser screens: place a browser keyboard and tie it to the screen with the linking tool: click the screen first, then the keyboard. Click the keyboard to type. To change the address, crouch and right-click the screen.
• Every other screen (SSH, SFTP, log, developer tools, workstation, terminal, remote connection, proxy): crouch and right-click the screen to type straight away. Each screen's own keyboard works too.

3. Link analysis screens

The log, developer tools and proxy screens analyse a browser. The SFTP screen uses an SSH session. There are two ways to link them:

• Linking tool: click the source screen (browser or SSH), then the analysis screen.
• Data cable: connect both directly or through the switch network.

4. Build the network

1. With the port installer and RJ45 ports in your inventory, add ports to screens.
2. Hold a data cable, click a port on one device, then a port on another.
3. Use a switch to join several devices. On the managed switch, wire the configuration tablet over the serial cable to create VLANs, disable ports or isolate them.
4. Use the cable adjuster to add waypoints or take a cable back.

5. Use the workstation

Connect a workstation screen to the network. It lists every reachable screen and rack module, honouring VLANs and disabled ports. Pick a device in the footer to see and control its screen.

6. Build a rack

1. Place the 12U floor rack on the ground and stack more sections on top (up to 6).
2. Holding a module, click the front of the rack. The height of the click picks the unit.
3. With an empty hand, click to open the panel: power modules on and off, remove them, open their ports and add network ports.
4. Crouch and click with an empty hand to open or close the glass door.
5. Run a data cable from the rack into the workstation network to see its modules.

7. Use the proxy

Link the proxy screen to a browser and pick a mode:

A paused request is forwarded unchanged after 120 seconds so the page never hangs. The timeout can be changed in the configuration.

Keyboard shortcuts

These apply to browser screens and to browser modules in a rack.

Creative tabs

NCAT Browser · NCAT SSH · NCAT Terminal · NCAT Proxy · NCAT Remote Connection · NCAT Cables · NCAT Network Equipment · NCAT Workstation · NCAT Rack and Modules · NCAT Furniture

Recipes

Everything can be crafted in survival. Names follow the game language.

Screens

Keyboards

Network and cables

Rack

Tools

Furniture

The NCAT Water Jug uses a special recipe: 8 glass blocks around a water bucket, filling the 3×3 grid. The jug comes out full.

Configuration

The files live in the Minecraft config folder and are created on first launch.

ncat_minecraft_client.toml (each player)

ncat_minecraft_common.toml (server and single player)

The file also contains options inherited from WebDisplays that do not affect NCAT features.

Security and responsible use

• Use SSH, RDP, VNC, the terminal and the proxy only on systems you own or are explicitly authorized to test.
• The terminal opens a shell on the player's own computer, as that player's user, and never on the server. Turn it off with terminal_enabled = false.
• The proxy only affects browsers on the player's own client. Keep it observe-only with proxy_enabled = false.
• SSH and RDP passwords stay on the client and are never saved in the world.
• Screens are visible to any nearby player. Log, developer tools and proxy show request headers and bodies, which can contain cookies and tokens.
• The inherited file server opens TCP port 25566 when a world loads. If you do not use it, turn it off with miniserv_port = 0.
• Use browser_options.blacklist to block domains on every screen.

Troubleshooting

Credits and licenses

• Based on WebDisplays, created by montoyo and maintained by CinemaMod Group, under the MIT license. See LICENSE.
• MCEF (CinemaMod) is a separate dependency and is not redistributed here.
• Bundled libraries: JSch 2.28.7 (Revised BSD and ISC), Netty 4.1.82 (Apache 2.0), xterm.js 5.5.0 and addon-fit 0.10.0 (MIT), noVNC 1.7.0 (MPL 2.0) and FreeRDP 3.32.1 (Apache 2.0).
• Full details, versions and notices in NOTICE.md.

Minecraft is a trademark of Mojang Studios. This is an unofficial project with no affiliation with Mojang or Microsoft.