Jabber/XMPP gateways & bridges with other networks.
- "Gateways" or "transports" enable users to connect to other networks (IRC, Matrix...) as if they had joined it directly; the gateway will create a user session on the remote network in a process called "puppeteering";
- "Bridges" connect collective spaces (such as chatrooms) across networks without user intervention ; they can relay message through a dedicated user (relay bot) or by "puppeteering" users on remote networks. Some remote networks also allow the relay bot to temporarily change its name with is referred to as "user spoofing".
The terms gateway and bridge are sometimes used interchangeably. For example, on the Matrix network both are referred to as "bridges" but it makes a distinction between "portaled" (= gatewayed) and "plumbed" (= bridged) rooms.
- Due to the often reverse-engineered nature of such systems they are prone to breaking and commonly are in violation of the Terms of Service, especially on commercial networks like Discord;
- Due to the problems matching different protocol features, usability is nearly always degraded on both sides;
- Some networks ban publicly accessible gateways as they are easily abused by spammers and technically difficult to differentiate from automated spam-bots.
Privacy & security
- Due to exposing users messages to external networks the privacy of users is typically not preserved and rarely is it possible to acquire consent of all users;
- Malicious gateways and bridges may monitor the entirety of messages going through them, as network encryption (TLS) is terminated from both sides on the gateway itself;
- Credentials (such as passwords) used by gateways for login purposes are sometimes stored on the gateway server; in particular, for password-less systems like Telegram there may also be a risk of permanent account takeover when using public gateways. 2FA should be used in such cases;
- Some gateways publicly expose the user's JID to other networks, sometimes publicly, contrary to how most XMPP services operate (an XMPP chatroom admin can always see a user's JID, but usually regular users can't); this information is exposed to remote network by the gateway for abuse prevention (being able to distinguish between individual users);
- User-spoofing bridges can be easily abused to impersonate users.
Gateway / bridge etiquette
- If you are the guest you have to play by the rules of the host. So if you for example use an XMPP -> IRC gateway you have to respect IRC conventions. But If you use a IRC -> XMPP gateway you have to respect XMPP conventions;
- Try to avoid using features that usually do not (reactions, threaded replies etc.) or only severely degraded (for example quoting) translate across gateway and bridges;
- Before setting up a bridge or gateway politely ask the channel operator or service owner if that is allowed (but in the case of commercial networks that might be impossible);
- In most cases gateways and bridges work only reliably when you are the service operator of both networks.