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

        • iAmTheTot@kbin.social
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          1 year ago

          On kbin (which you are) you can go to /d/theinstanceyoudontlike and there’s a block button, just like every user page and magazine page.

            • wagesj45@kbin.social
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              1 year ago

              kbin is still in its growing pains phase. there are tons of little user experience items that need to be worked on. good thing is that @ernest is working hard on it.

          • 1st@kbin.social
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            1 year ago

            Now I’m curious what would happen if I defederated from Kbin.social on kbin.social

          • Mr_Figtree@kbin.social
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            1 year ago

            Does that actually work for you? I’m still seeing posts from magazines on domains that I blocked that way. It looks to me like it only blocks articles, and also link posts to the domain, but not link posts on magazines from the domain.

            • naura@kbin.social
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              1 year ago

              What I hear is that a copy is still made so the posts made before defederalization is available and basically forks without them connected now at the point of being deferated

    • ginerel@kbin.social
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      1 year ago

      I hate tankies myself as well, but I also hate that some communities are only created on lemmy.ml. Plus some official subreddits moved over there as well (and no - no far-left ones).

    • CoderKat@kbin.social
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      1 year ago

      Problem is that there’s a bunch of major communities on that instance. They have no affiliation with the server admins and mostly just chose the instance because it seemed like the default very early in the migration to the Fediverse.

      • Cloudless@kbin.social
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        1 year ago

        The term “tankie” is a slang term used to describe a person who supports or apologizes for the actions of authoritarian communist regimes, particularly those that have used tanks or military force to suppress opposition or maintain control. The term originated from the Soviet Union’s use of tanks to quell protests and uprisings, most notably the 1956 Hungarian Revolution and the 1968 Prague Spring in Czechoslovakia.

        While there may be varying interpretations and uses of the term, it is generally used pejoratively to criticize individuals who defend or downplay the human rights abuses, political repression, or atrocities committed by these regimes.

        (ChatGPT)