mjolnir

A moderation tool for Matrix. Visit #mjolnir:matrix.org for more information.

Features

As an all-in-one moderation tool, it can protect your server from malicious invites, spam messages, and whatever else you don't want. In addition to server-level protection, Mjolnir is great for communities wanting to protect their rooms without having to use their personal accounts for moderation.

The bot by default includes support for bans, redactions, anti-spam, server ACLs, room directory changes, room alias transfers, account deactivation, room shutdown, and more.

A Synapse module is also available to apply the same rulesets the bot uses across an entire homeserver.

Bot configuration

It is recommended to use Pantalaimon so your management room can be encrypted. This also applies if you are looking to moderate an encrypted room.

If you aren't using encrypted rooms anywhere, get an access token by opening Riot in an incognito/private window and log in as the bot. From the Help & Support tab in settings there is an access token field - copy and paste that into your config. Most importantly: do not log out and instead just close the window. Logging out will make the token you just copied useless.

Note: Mjolnir expects to be free of rate limiting - see Synapse #6286 for information on how to achieve this.

Note: To deactivate users, move aliases, shutdown rooms, etc Mjolnir will need to be a server admin.

Docker installation (preferred)

Mjolnir is on Docker Hub as matrixdotorg/mjolnir but can be built yourself with docker build -t mjolnir ..

git clone https://github.com/matrix-org/mjolnir.git
cd mjolnir

# Copy and edit the config. It is not recommended to change the data path.
mkdir -p /etc/mjolnir/config
cp config/default.yaml /etc/mjolnir/config/production.yaml
nano /etc/mjolnir/config/production.yaml

docker run --rm -it -v /etc/mjolnir:/data matrixdotorg/mjolnir:latest

Build it (alternative installation)

This bot requires yarn and Node 10.

git clone https://github.com/matrix-org/mjolnir.git
cd mjolnir

yarn install
yarn build

# Copy and edit the config. It *is* recommended to change the data path.
cp config/default.yaml config/development.yaml
nano config/development.yaml

node lib/index.js

Quickstart guide

After your bot is up and running, you'll want to run a couple commands to get everything set up:

1. !mjolnir list create COC code-of-conduct-ban-list - This will create a new ban list with the shortcode COC and an alias of #code-of-conduct-ban-list:example.org. You will be invited to the room it creates automatically where you can change settings such as the visibility of the room.
2. !mjolnir default COC - This sets the default ban list to the list we just created to help with the ban commands later on.
3. Review the Moderator's Guide.
4. Review !mjolnir help to see what else the bot can do.

Synapse Module

Using the bot to manage your rooms is great, however if you want to use your ban lists (or someone else's) on your server to affect all of your users then a Synapse module is needed. Primarily meant to block invites from undesired homeservers/users, Mjolnir's Synapse module is a way to interpret ban lists and apply them to your entire homeserver.

Warning: This module works by running generated Python code in your homeserver. The code is generated based off the rules provided in the ban lists, which may include crafted rules which may allow unrestricted access to your server. Only use lists you trust and do not use anyone else's infrastructure to get the ruleset from - only use infrastructure that you control.

If this is acceptable, the following steps may be performed.

First, run the Docker image for the rule server. This is what will be serving the generated Python for the Synapse antispam module to read from. This rule server will serve the Python off a webserver at /api/v1/py_rules which must be accessible by wherever Synapse is installed. It is not recommended to expose this webserver to the outside world.

docker run --rm -d -v /etc/mjolnir/ruleserver.yaml:/data/config/production.yaml -p 127.0.0.0:8080:8080 matrixdotorg/mjolnir

Note: the exact same Mjolnir image is used to run the rule server. To configure using the rule server instead of the bot function, see the ruleServer options in the config.

After that is running, install the module to your Synapse python environment:

pip install -e "git+https://github.com/matrix-org/mjolnir.git#egg=mjolnir&subdirectory=synapse_antispam"

Note: Where your python environment is depends on your installation method. Visit #synapse:matrix.org if you're not sure.

Then add the following to your homeserver.yaml:

spam_checker:
  - module: mjolnir.AntiSpam
    config:
      # Where the antispam module should periodically retrieve updated rules from. This
      # should be pointed at the Mjolnir rule server.
      rules_url: 'http://localhost:8080/api/v1/py_rules'

Note: Although this is described as a "spam checker", it does much more than fight spam.

Be sure to change the configuration to match your setup. If you change the configuration, you will need to restart Synapse. You'll also need to restart Synapse to install the plugin.

Development

TODO. It's a TypeScript project with a linter.