barista

I discovered yesterday evening that Lemmy.ml is blocking all inbound ActivityPub requests from /kbin instances. Specifically, a 403 'access denied' is returned when the user agent contains "kbinBot" anywhere in the string. This has been causing a cascade of failures with federation for many server owners, flooding the message queue with transport errors.

This doesn't appear to be a mistake; it has been done very deliberately, only on Lemmy.ml. Lemmy.world and other large instances do not exhibit the same behavior. It also isn't a side effect of the bug introduced in Lemmy 0.18. You can observe by sending the following in a terminal

> curl -I --user-agent "kbinBot v0.1" https://lemmy.world/u/test
HTTP/2 200
[...]

> curl -I --user-agent "kbinBot v0.1" https://lemmy.ml/u/test                                
HTTP/2 403
[...]

> curl -I --user-agent "notKbinBot v0.1" https://lemmy.ml/u/test
HTTP/2 403
[...]

> curl -I --user-agent "placeholder-user-agent" https://lemmy.ml/u/test
HTTP/2 200
[...]

Additional evidence of this not being a Lemmy 0.18 bug:

• This occurs when making web requests to any location on the Lemmy.ml webserver, not just ActivityPub endpoints.

• Go to https://fedidb.org/software/lemmy and pick an instance running 0.18.0. Perform the above commands, replacing the URL for Lemmy.ml with that particular instance's address.

If this continues, my instance may need to defederate from Lemmy.ml. This is especially problematic because Lemmy.ml continues to federate information outbound to other kbin instances while refusing to allow inbound communication from them.

Spoofing the user agent is less than ideal, and doesn't respect Lemmy.ml's potential wish to not be contacted by /kbin instances. I don't post this to create division between communities, but I do hope that I can draw awareness to what's going on here. Defederating /kbin instances entirely would even be better than arbitrarily denying access one-way. This said, we should all attempt to maintain a good-faith interpretation until otherwise indicated by the Lemmy developers. It's possibel that this is a firewall misconfiguration or some other webserver-related bug.

Relevant comment from me (#354 - [BUG] Critical errors/failed messages during messenger:consume)

Edits:

• Yes, people have already tried reaching out to the Lemmy instance admins in their Matrix room with no answer.

• Someone has posed a question on Lemmy.ml about the block here: https://lemmy.ml/post/1563840

Hi all,

I'm a developer that has an interest in online communities, fediverse software and, at a point in the very recent past, consuming and creating a lot of Reddit content. Discontented with regards to the direction Reddit has taken, I've taken it upon myself to start a small, general-purpose instance to give back to the /kbin community and help reduce load. The instance is hosted on a secure, well-equipped dedicated server and should support a large influx of users and communities. I will be regularly administrating it (and may even seek fellow admins); but ideally, administration will be hands-off and moderators will take onus for their magazines.

Come check us out at kbin.cafe. I'll be happy to answer any lingering questions in this thread.

Please be sure to report any issues by messaging me or emailing us at the address found in the linked post. Currently some avatars for some federated magazines are missing, but this will be resolved soon.

Thanks for reading!