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:
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This occurs when making web requests to any location on the Lemmy.ml webserver, not just ActivityPub endpoints.
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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:
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Yes, people have already tried reaching out to the Lemmy instance admins in their Matrix room with no answer.
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Someone has posed a question on Lemmy.ml about the block here: https://lemmy.ml/post/1563840
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.
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.
IMHO Kbin actually looks better on my mobile than on desktop.
I have both set to the aqua/greenish theme and on mobile my upvotes/interactions show up bright yellow...but on desktop there's no difference. Even if I take off "follow desktop personalization theme". (firefox for both.)
I'm glad you think so. Please see the attached screenshot for an example of what I'm talking about. I'd like to have the text one size bigger so I can read it more easily, but then whole words are cut off or missing.