cross-posted from: https://lemmygrad.ml/post/1294067

What is Matrix?

Matrix ≈ Discord - tracking + end-to-end encryption (by default)

Matrix is a protocol for real-time communication (text, audio, and video) implemented by various applications ("clients") -- the official one is Element for Linux, macOS, Windows, Android, and iOS), but there are many others, e.g. those listed here. It's also federated, like Lemmy. To use a Matrix client, you need to make a Matrix account at one of the Matrix homeservers (similar to how you can make an account on lemmygrad.ml or lemmy.ml but still access both of them). We have our own Matrix homeserver at genzedong.xyz, and you don't need an email address to register an account there.

How do I join the space?

(If you already have a Matrix account, skip to step 3)

1. Download a Matrix client (e.g. Element) on your device.
2. Create an account in the client. You can select genzedong.xyz as your homeserver here; if you choose the default matrix.org, you'll need to enter an email address. If it doesn't work on your client, try using Element Web for registration.
3. Log in.
4. If you have a Lemmygrad account with a solid posting history (moderator discretion applies), post your username in #vetting-answers-encrypted:genzedong.xyz or #vetting-answers:genzedong.xyz (make sure that your Lemmygrad account has your Matrix account listed in your profile), or request an invite on Lemmygrad by commenting or PMing your Matrix account name; otherwise, read the vetting questions in #vetting-questions:genzedong.xyz and answer them in either of the two aforementioned rooms. (These instructions are also available in #welcome:genzedong.xyz)

Of course comrades from Hexbear can join too, you can make an account on any homeserver you wish and join! Basically a group chat with communists. There's also a channel for Technology, Linux, learning Spanish, etc.

cross-posted from: https://lemmy.ca/post/4273025

Someone made a tool to remove CSAM content automatically: https://github.com/db0/lemmy-safety

You can upload images to a Lemmy instance without anyone knowing that the image is there if the admins are not regularly checking their pictrs database.

To do this, you create a post on any Lemmy instance, upload an image, and never click the "Create" button. The post is never created but the image is uploaded. Because the post isn't created, nobody knows that the image is uploaded.

You can also go to any post, upload a picture in the comment, copy the URL and never post the comment. You can also upload an image as your avatar or banner and just close the tab. The image will still reside in the server.

You can (possibly) do the same with community icons and banners.

Why does this matter?

Because anyone can upload illegal images without the admin knowing and the admin will be liable for it. With everything that has been going on lately, I wanted to remind all of you about this. Don't think that disabling cache is enough. Bad actors can secretly stash illegal images on your Lemmy instance if you aren't checking!

These bad actors can then share these links around and you would never know! They can report it to the FBI and if you haven't taken it down (because you did not know) for a certain period, say goodbye to your instance and see you in court.

Only your backend admins who have access to the database (or object storage or whatever) can check this, meaning non-backend admins and moderators WILL NOT BE ABLE TO MONITOR THESE, and regular users WILL NOT BE ABLE TO REPORT THESE.

Aren't these images deleted if they aren't used for the post/comment/banner/avatar/icon?

NOPE! The image actually stays uploaded! Lemmy doesn't check if the images are used! Try it out yourself. Just make sure to copy the link by copying the link text or copying it by clicking the image then "copy image link".

How come this hasn't been addressed before?

I don't know. I am fairly certain that this has been brought up before. Nobody paid attention but I'm bringing it up again after all the shit that happened in the past week. I can't even find it on the GitHub issue tracker.

I'm an instance administrator, what the fuck do I do?

Check your pictrs images (good luck) or nuke it. Disable pictrs, restrict sign ups, or watch your database like a hawk. You can also delete your instance.

Good luck.