PyLink Relay is a plugin that provides transparent relays between channels on different networks. On participating networks, PyLink connects as a services server and mirrors messages as well as user lists from relayed channels, the latter by creating "puppet" service clients for all remote users in common channels. Relay offers an alternative to classic IRC linking, letting networks share channels on demand while retaining their services, policies, and distinct branding. By default, Relay also secures channels from remote oper overrides via a CLAIM feature, which restricts /kick, /mode, and /topic changes from un-opped users unless they are granted permissions via CLAIM.
Relay shares many ideas from its predecessor Janus, but is a complete rewrite in Python. This guide goes over some of the basic commands in Relay, as well as some must-know gotchas.
By default, Relay will automatically tag users from other networks with a suffix such as `/net`. This prevents confusing nick collisions if the same nick is used on multiple linked networks, and ensure that nicks from remote networks are all isolated into their own namespaces.
How is this relevant to an operator? It means that you **cannot ban users** using banmasks such as `*/net1!*@*`! The nick suffix is something PyLink adds artificially; on `net1`'s IRCd, which check the bans locally, the nick suffix doesn't exist and will therefore *not* match anyone.
### Services compatibility
While PyLink is generally able to run independently of individual networks' services, there are some gotchas. This list briefly details services features that have been known to cause problems with Relay. **Using any of these features in conjunction with Relay is *not* supported.**
- Rationale: it is common for a person to want to connect to multiple networks in a Relay instance, because they are still independent entities. You can still use IRCd-side clones prevention, which sanely blocks connections instead of killing / banning everyone involved.
- Atheme: **The ChanFix service should be disabled**
- Rationale: ChanFix is incompatible with Relay CLAIM because it overrides ops on relay channels whenever they appear "opless". This basic op check is unable to consider the case of remote channel services not being set to join channels, and will instead cause join/message/part spam as CLAIM reverts the ChanFix service's mode changes.
- Clientbot is an exception to this, though you may want to add Clientbot networks to CLAIM so that PyLink doesn't try to reverse modes set by services on the Clientbot network.
- Rationale: This will just make PyLink split off - you should instead [delink any problem networks / channels](#dealing-with-disputes-and-emergencies).
- Not following these rules means that it's very easy for the Relay instances to go in a loop should an operator run the wrong command, which will hammer your CPU and relentlessly spam your channels.
The basic steps for setting up a relay is to first CREATE the channel with PyLink on the network that owns it, and run LINK from each network that wants to link to it. In most cases, you want to run CREATE on the network where the channel is registered with services.
Importantly, this means that CREATE and LINK have to be run on different networks for any particular channel, and that you should only run CREATE once for each distinct channel! This setup is intended to allow individual network admins to pick and choose channels they want to participate in.
- A channel created on a particular network is considered to be _owned_ by that network; this affects how CLAIM works for instance (see the next section)
Channel claiming is a feature which prevents oper override (MODE, KICK, TOPIC, KILL, OJOIN, ...) by other networks' operators from affecting your channels. By default, CLAIM is enabled for all new channels, though this can be configured via the [`relay::enable_default_claim` option](https://github.com/jlu5/PyLink/blob/3.0.0/example-conf.yml#L828-L831). Unless the claimed network list of a channel is _empty__, oper override will only be allowed from networks on the CLAIM list (plus the network that owns the channel).
Note: these commands must be run from the network which owns the channel in question!
LINKACL allows you to allow or deny networks from linking to your channel. New channels are created using a blacklist by default, though this can be configured via the [`relay::linkacl_use_whitelist` option](https://github.com/jlu5/PyLink/blob/3.0.0/example-conf.yml#L823-L826).
- Note that when you switch between LINKACL modes, the LINKACL entries from the previous mode are stored and stashed away. This means that you will get an empty LINKACL list in the new LINKACL mode if you haven't used it already, and that you can reload the previous LINKACL mode's entries by switching back to it at any point.
The best thing to do in the event of a dispute is to delink the problem networks / channels. In order for individual networks to maintain their autonomy, KILLs and network bans (K/G/ZLINE) will most often *not* behave the way you expect them to.
Special kill handling was introduced in PyLink 2.0, while in previous versions they were always bounced:
1) If the sender was a server and not a client, reject the kill. (This prevents services messups from wreaking havoc across the relay)
2) If the target and source networks share a [kill share pool](https://github.com/jlu5/PyLink/blob/3.0.0/example-conf.yml#L782-L792), relay the kill as-is.
3) Otherwise, check every channel that the kill target is in:
- If the sender is opped or has claim access in a channel, forward the KILL as a kick in that channel.
- Otherwise, bounce the kill silently (i.e. rejoin the user immediately).
Network bans are purposely not supported; see https://github.com/jlu5/PyLink/issues/521#issuecomment-352316396.
### Delinking channels
To delink another network from a channel your network owns:
-`/msg PyLink delink #yourchannel badnetwork`
To delink your network from a bad network's channel:
-`/msg PyLink delink #badchannel`
Basically, only one of the two above commands will work for one specific channel. Almost always, the network that owns a channel should be the one who has it registered via their services. You can see a list of channels by typing `/msg PyLink linked`.
