Double puppeting

You can replace the Matrix ghost of your remote account with your Matrix account. When you do so, messages that you send from other clients will be sent from your 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.

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.

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)

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:

   # 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)
   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 registration file the same way as the main bridge registration (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). Remember to quote the value since : is a special character in YAML.

   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.

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

0. 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).
1. Add the login shared secret to bridge → login_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.
2. 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)

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).

The benefit of this method is that appservice login is in the spec, so it can work on all homeserver implementations (caveat: as of writing, Dendrite and Conduit do not implement the spec).

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.