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

  • ernest@kbin.social
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    1 year ago

    It’s possible that this is a consequence of the latest Lemmy update, in which a lot has changed. I have noted that kbin has some issues with request signature in communication with certain instances. I will try to check it tomorrow first thing in the morning.

  • phi1997@kbin.social
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    1 year ago

    If they don’t want us to communicate with the users of their server, they should be defederated. Sucks for the users, but they can hop to another server whose admins don’t break communication inelegantly and ghost admins who want to know what’s going on.

    If it’s just a bug, then obviously we should wait for it to be fixed, but if they’re not even saying they’ll look into it, I don’t have much hope.

      • Deceptichum@kbin.social
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        1 year ago

        Before assuming no one has asked them, let’s read the post

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

        • ripcord@kbin.social
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          1 year ago

          Ok, but, as the thread over there says, it’s not like they’re singling out kbin as far as the code shows. Just because no one there has answered yet doesn’t mean they’ve refused to answer. Give it some time or some actual replies before assuming the worst.

          Also that edit was added after my question.

          It’s been a few hours, this is way way too fast for the pitchforks to come out.

  • svovl@kbin.social
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    1 year ago

    In the spirit of a thriving fediverse, I suggest not to assume the worst of other parts of it before we know a bit more of what’s going on.

  • Eisenhowever@kbin.social
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    1 year ago

    Doesnt surprise me, the developers of lemmy (which are owners of .ml) have an agenda. They are into censoring on ukraine news, and other stuff. I dont get why people are choosing lemmy over kbin when they are equally bad looking

        • slicedcheesegremlin@kbin.social
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          1 year ago

          yeah, kbin is probably the nicest looking reddit alternative i’ve seen. Really sleek design without leaning into the overly overly mobile-focused watered down New Reddit bs, while also not nearly as hideous as old reddit.

          • mochi@kbin.social
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            1 year ago

            I do wish kbin looked a bit better on mobile, though. I have larger font on my iPhone and instead of wrapping, the text just goes off the screen and can’t be viewed.