A moderation tool for Matrix. Visit #mjolnir:matrix.org for more information.
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.
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 14.
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
After your bot is up and running, you'll want to run a couple commands to get everything set up:
!mjolnir list create COC code-of-conduct-ban-list- This will create a new ban list with the shortcode
COCand 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.
!mjolnir default COC- This sets the default ban list to the list we just created to help with the ban commands later on.
- Review the Moderator's Guide.
!mjolnir helpto see what else the bot can do.
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.
First, 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
spam_checker: module: mjolnir.AntiSpam config: # Prevent servers/users in the ban lists from inviting users on this # server to rooms. Default true. block_invites: true # Flag messages sent by servers/users in the ban lists as spam. Currently # this means that spammy messages will appear as empty to users. Default # false. block_messages: false # Remove users from the user directory search by filtering matrix IDs and # display names by the entries in the user ban list. Default false. block_usernames: false # The room IDs of the ban lists to honour. Unlike other parts of Mjolnir, # this list cannot be room aliases or permalinks. This server is expected # to already be joined to the room - Mjolnir will not automatically join # these rooms. ban_lists: - "!roomid:example.org"
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. Your server is expected to already be participating in the ban lists - if it is not, you will need to have a user on your homeserver join. The antispam module will not join the rooms for you.
If you change the configuration, you will need to restart Synapse. You'll also need to restart Synapse to install the plugin.
Enabling readable abuse reports
Since version 1.2, Mjölnir offers the ability to replace the Matrix endpoint used to report abuse and display it into a room, instead of requiring you to request this data from an admin API.
This requires two configuration steps:
- In your Mjölnir configuration file, typically
/etc/mjolnir/config/production.yaml, copy and paste the
default.yaml, if you don't have it yet (it appears with version 1.20) and set
enabled: truefor both
- Setup a reverse proxy that will redirect requests from
hostis the host where you run Mjölnir, and
portis the port you configured in
production.yaml. For an example nginx configuration, see
test/nginx.conf. It's the confirmation we use during runtime testing.
This mechanism can extract some information from unencrypted rooms. We have taken precautions to ensure that this cannot be abused: the only case in which this feature will publish information from room foo is:
- If it is used by a member of room foo; AND
- If said member did witness the event; AND
- If the event was unencrypted; AND
- If the event was not redacted/removed/...
Essentially, this is a more restricted variant of the Admin APIs available on homeservers.
However, if you are uncomfortable with this, please do not activate this feature.
Also, you should probably setup your
production.yaml to ensure that the web
server can only receive requests from your reverse proxy (e.g.
TODO. It's a TypeScript project with a linter.
Development and testing with mx-tester
WARNING: mx-tester is currently work in progress, but it can still save you some time and is better than struggling with nothing.
If you have docker installed you can quickly get setup with a development environment by using mx-tester.
To use mx-tester you will need to have rust installed. You can do that at rustup or here, you should probably also check your distro's documentation first to see if they have specific instructions for installing rust.
Once rust is installed you can install mx-tester like so.
$ cargo install mx-tester
Once you have mx-tester installed you we will want to build a synapse image with synapse_antispam from the mjolnir project root.
$ mx-tester build
Then we can start a container that uses that image and the config in
$ mx-tester up
Once you have called
mx-tester up you can run the integration tests.
$ yarn test:integration
mx-tester up, if we want to play with mojlnir locally we can run the following and then point a matrix client to http://localhost:9999.
You should then be able to join the management room at
Once we are finished developing we can stop the synapse container.
Running integration tests
The integration tests can be run with
The config that the tests use is in
and by default this is configured to work with the server specified in
but you can configure it however you like to run against your own setup.