Discord ZeroTier Bot

Intro

As part of the recent BSides Vancouver CTF, we were using ZeroTier as our VPN provider to enable access to the challenges. We created a private ZeroTier network and were manually authorizing player machines that were joining the CTF.

Discord ZeroTier Bot automates ZeroTier node authorization and allows users of your Discord server request their node authorization, and will also reference ZeroTier node to the Discord user that requested the authorization.

Setup

Step 1 - .env file

Create the .env file to use as config:

cp template.env .env

Step 2 - Discord Bot

1. You need a Discord user account, and admin access to t he Discord server where you want to use the Bot.
2. Head to Discord Developer Portal, login, and create a new app. I'd suggest you name it ZeroTier Bot (this will be the username for your Bot in Discord).
3. Create a Bot for your application by clicking Bot in the application settings, then select Add Bot.
4. Copy the Bot token and save it in the .env as DISCORD_TOKEN

Step 3 - Authorize the Bot

1. In the application settings, select OAuth2, then select bot under Scopes.
2. Under Bot Permissions select Send Messages and Use Slash Commands.
3. Open the displayed URL and authorize the Bot in your Discord server.

Step 3 - ZeroTier

1. Login to ZeroTier.
2. Go to your Account settings and create a new API token.
3. Save the token in the .env file as ZT_TOKEN.
4. Save the network ID in the .env as ZT_NETWORK (create a new network if you haven't yet).

Step 4 - Start the Bot

Build the Docker image:

docker build -t discord-zerotier-bot .

Start the Bot:

docker run --rm -it --env-file .env discord-zerotier-bot

Usage

Note: once the bot is started, it may take up to an hour for the slash commands to register on your server. If the bot isn't showing any errors, have a bit of patience.

The following slash commands will now be available in your server:

• /zerotier-bot help - show help message
• /zerotier-bot register - request node authorization

The bot will add Discord username of the requesting user as the name for the nodes that it authorizes. The bot also checks if string ban is present in the node description and will not authorize those nodes, this allows node banning in ZeroTier. Users have to join the network first before requesting ZeroTier authorization through the Bot.

TODO

• Add a restricted /zerotier ban command to ban nodes.
• Automate image build and push to Docker Hub.