Double puppeting

By giving the bridge access to your Matrix account, you can replace the Matrix ghost of your remote account. When you do so, messages that you send from other clients will be sent from your real Matrix account instead of the default ghost user. In most of the bridges, this is necessary to bridge DMs you send from other clients to Matrix.

Benefits of double puppeting:

  • Automatically accept invites to new chats.
  • Bridge messages you send from the native app in direct chats.
  • Bridge messages you send from the native app as your Matrix real user instead of the bridge's ghost user.
  • Optionally sync some details like low priority, favorites, mute status and direct chat status.

Automatically

Instead of requiring everyone to manually enable double puppeting, you can give the bridge access to log in on its own. This makes the process much smoother for users, and removes problems if the access token getting invalidated, as the bridge can simply automatically relogin.

This method requires administrator access to the homeserver, so it can't be used if your account is on someone elses server (e.g. using self-hosted bridges from matrix.org). In such cases, manual login is the only option.

Appservice method (new)

N.B. This method is not supported in the legacy (Python) Signal bridge nor the current iMessage and Slack bridges. You can use the alternative methods like shared secret login documented below for those.

This method doesn't log in at all, instead it uses an as_token directly with the user_id query parameter. It should work on all homeserver implementations that support appservices. However, some servers don't follow the spec, and may not work with a null url field. This method also makes timestamp massaging work correctly and disables ratelimiting for double puppeted messages.

Since there's no login step, this method also has the benefit of not adding confusing sessions to the session list visible to the user.

  1. First create a new appservice registration file. Don't touch the bridge's main registration file, and make sure the ID and as/hs tokens are different (having multiple appservices with the same ID or as_token isn't allowed).

    # The ID doesn't really matter, put whatever you want.
    id: doublepuppet
    # The URL is intentionally left empty (null), as the homeserver shouldn't
    # push events anywhere for this extra appservice. If you use a
    # non-spec-compliant server, you may need to put some fake URL here.
    url:
    # Generate random strings for these three fields. Only the as_token really
    # matters, hs_token is never used because there's no url, and the default
    # user (sender_localpart) is never used either.
    as_token: random string
    hs_token: random string
    sender_localpart: random string
    # Bridges don't like ratelimiting. This should only apply when using the
    # as_token, normal user tokens will still be ratelimited.
    rate_limited: false
    namespaces:
      users:
      # Replace your\.domain with your server name (escape dots for regex)
      - regex: '@.*:your\.domain'
        # This must be false so the appservice doesn't take over all users completely.
        exclusive: false
    
  2. Install the new registration file the usual way (see Registering appservices).

  3. Finally set as_token:$TOKEN as the secret in login_shared_secret_map (e.g. if you have as_token: meow in the registration, set as_token:meow in the bridge config).

    bridge:
      ...
      login_shared_secret_map:
        your.domain: "as_token:meow"
      ...
    

If you set up double puppeting for multiple bridges, you can safely reuse the same registration by just setting the same token in the config of each bridge (i.e. no need to create a new double puppeting registration for each bridge).

This method works for other homeservers too, you just have to create a new registration file for each server, add the token to login_shared_secret_map, and also add the server address to double_puppet_server_map (for the bridge server, adding to the server map is not necessary as it defaults to using the one configured in homeserver -> address).

Shared secret method (legacy, synapse-only)

  1. Set up matrix-synapse-shared-secret-auth on your Synapse.
    • Make sure you set m_login_password_support_enabled to true in the config.
    • You should also set com_devture_shared_secret_auth_support_enabled to false as having that option enabled breaks user-interactive auth in some clients (e.g. you won't be able to sign out other devices or reset cross-signing in Element).
  2. Add the login shared secret to bridgelogin_shared_secret_map in the config file under the correct server name.
    • In mautrix-imessage and in past versions of other bridges, the field is called login_shared_secret, as double puppeting was only supported for local users.
  3. The bridge will now automatically enable double puppeting for all users on servers with a shared secret set when they log into the bridge.

Appservice method (legacy, deprecated)

This method is not recommended. Doing this causes all events from rooms your user is in to be pushed to the bridge, which then makes the bridge bot join the rooms (as the bridge assumes it only receives events meant for it).

Additionally, it only works for users who are on the same homeserver as the bridge, it can't be used with other homeservers at all (even with admin access).

  1. Modify the registration file to add a user namespace covering all users in addition to the bridge_.+ and bridgebot regexes. Make sure you set exclusive: false for the new regex.

    namespaces:
      users:
      - ...existing regexes...
      - regex: '@.*:your\.domain'
        exclusive: false
    

    Restart the homeserver after modifying the registration.

  2. Set the shared secret in the bridge config to appservice:

    bridge:
      ...
      login_shared_secret_map:
        your.domain: appservice
      ...
    
  3. The bridge will now use appservice login enable double puppeting for all local users when they log into the bridge.

Manually

Double puppeting can only be enabled after logging into the bridge. As with the normal login, you must do this in a private chat with the bridge bot.

N.B. This method is not currently supported in mautrix-imessage and mautrix-slack.

  1. Log in on the homeserver to get an access token, for example with the command
    $ curl -XPOST -d '{"type":"m.login.password","identifier":{"type": "m.id.user", "user": "example"},"password":"wordpass","initial_device_display_name":"a fancy bridge"}' https://example.com/_matrix/client/v3/login
    
    You may want to change the initial_device_display_name field to something more descriptive, or rename it from another client after logging in.
    • In the past, getting a token from an existing client like Element was the recommended easy way. However, multiple clients using the same token can cause issues with encryption, so doing that is no longer allowed.
  2. Send login-matrix <access token> to the bridge bot. For the Telegram bridge, send login-matrix without the access token, then send the access token in a separate message.
  3. After logging in, the default Matrix ghost of your remote account should leave rooms and your account should join all rooms the ghost was in automatically.

Manually with SSO

If you only have SSO login on your homeserver, the above example with password login won't work. However, doing SSO login manually is still possible, just a bit more work.

  1. Open https://example.com/_matrix/client/v3/login/sso/redirect?redirectUrl=http://localhost:12345 in a browser. The redirect URL at the end doesn't have to be a real server, since you can just copy the relevant value in the browser URL bar after the redirect.
  2. Go through the SSO process, then once it redirects to localhost:12345, copy the value of the loginToken query parameter.
  3. Log into the homeserver with the login token:
    $ curl -XPOST -d '{"type":"m.login.token","token":"THE TOKEN","initial_device_display_name":"a fancy bridge"}' https://example.com/_matrix/client/v3/login
    
  4. Follow steps 2 and 3 of the normal password login instructions.