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

  • DreamerOfImprobableDreams@kbin.social
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    1 year ago

    True, but the original intent was that defederation would be a nuclear option, reserved only for instances that totally failed to moderate stuff like hate speech, bot activity, etc-- given that it damages the Fediverse as a whole.

    The lemmy.ml admins are free to federate or defederate from other instances as they please-- and we’re free to criticize their decision as we please, too.

      • Klear@lemmy.world
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        1 year ago

        Do you want another /r/the_donald? Because that’s how you get another /r/the_donald.

      • CAVOK@lemmy.world
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        1 year ago

        Depends on where you live, doesn’t it? It could be illegal not to remove hate speech.

      • this
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        1 year ago

        If you would like to be on an instance/community that allows hate speech, then by all means thats your choice. I however want to have a safe space for specific discussion topics and don’t mind those communities being moderated. maybe thats not the experience you would like to have online but for me I think moderation is nessesary (in general). Defederation Is just the nuclear option for moderation, meant for extreme cases where an entire instance is causing issues for another instance, there should always be tools on the community mod and user levels to address the issue first, but some of those tools don’t exist right now. The whole idea of safe spaces for discussion conflicts with the freedom to do hate speech and thats just human nature.

      • pup_atlas@pawb.social
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        1 year ago

        On top of that being literally illegal in most populous jurisdictions, communities cannot tolerate those who are intolerant. Leave.