Nibodhika

No need to apologize, it's a weird choice from Plex, I would have never guessed that this is how it works if I hadn't suffered outages myself, and I'm amazed that not many people call them out on this, it seems completely against what most self-hosting people are looking for, but they seem to defend Plex with teeth and nails.

First of all I agree with most of your a, b and c points, just would like to point out that while it's true that Docker containers provide an extra level of security they're not as closed down as people sometimes believe, but as a general rule I agree with everything you said.

But you're wrong about the way Plex works, this is a quote from their documentation:

So, your Plex Media Server basically “relays” the media stream through our server so that your app can access it since the app can’t connect with your server directly.

If that's not clear enough:

Your security and privacy is important to us. When you have enabled secure connections on your Plex Media Server, then your streaming will continue to be secure and encrypted even when using our Relay feature. (When using secure connections, the content is encrypted end-to-end and tunneled through our Relay. The connection is not terminated on our servers and only your Plex Media Server has the certificate.)

So it's very clear data is streaming through their relay server, which goes back to my original point of I expect that to be a paid feature, it's using bandwidth from their relay servers.

As for the security again you're wrong, authentication happens on the Plex remote server, not on your local one, which is why you can't use Plex without internet (part of my dislike for them). So you connect to Plex remote server and authenticate there, you then get a client that's talking to the remote server, even if someone was able to bypass that login they would be inside a Plex owned server, not yours, they would need to then exploit whatever API exists between your home server and that one to jump to your machine, so it's an extra jump needed, again similarly to having Authelia/Authentik in front of Jellyfin.

You are, authentication on the VPS, you're relying on Jellyfin authentication against the internet. Correct me if I'm wrong, but this is your suggested setup: [home server] Jellyfin -> [remote server] Reverse Proxy -> [remote machine] users. Let's imagine a scenario where Jellyfin has a bug that if you leave the password empty it logs you in (I know, it's an exaggeration but just for the sake of argument, an SQL injection or other similar attacks would be more plausible but I'm trying to keep things simple), on your setup now anyone can log into your Jellyfin and from there it's one jump to your home server. On Plex's solution even if Plex authentication gets compromised the attacker only got access to the remote server, and would now need to find another vulnerability to jump to your Plex at home.

Putting something like Authelia/Authentik on a VPS in front of Jellyfin is a similar approach, but the Jellyfin client can't handle third party authentication AFAIK

For remote streaming they do, here are their docs on it https://support.plex.tv/articles/216766168-accessing-a-server-through-relay/

From that documentation:

So, your Plex Media Server basically “relays” the media stream through our server so that your app can access it since the app can’t connect with your server directly.

No, the article only mentions the feature by name, the docs for the feature mentions the relay https://support.plex.tv/articles/216766168-accessing-a-server-through-relay/

Using a relay server to separate online from home connection

It's not, not directly at least, and that's what everyone is ignoring here. You probably understand the value on Authelia/Authentik but you're failing to see that the Plex relay server is taking that same mantle here, so even if someone managed to compromise the relay server it's still not on your home server, whereas exposing jellyfin directly to the internet only requires one service to be compromised.

In some way is different from directly, on Plex you're behind a relay server so it's akin to being behind a VPS running Authentik/Authelia in front of the service on your home. Compromising the relay server does not necessarily compromises your home server, so it's not direct like putting Jellyfin on a reverse Proxy would be.

That exposes Jellyfin to the internet, so it's my option 1.

How do you do this on Jellyfin? The only ways I'm familiar with is to expose Jellyfin to the internet or access it through Tailscale, would love to hear alternatives.

Edit: From the replies I think that either I don't understand how this feature works or many people here don't, so I'll give an overview of my understanding and explain why this is different from anything you can do on Jellyfin and what's the closest you can come.

You are running Plex-home in your house, Plex-home connects to Plex-server hosted by Plex and establishes a reverse connection that's only accessible by Plex-server, i.e. you can't access your Plex-home outside of your house. When you login on Plex you're logging in to Plex-server and if you're in the same network as Plex-home you get redirected to form a direct connection with it, if not (and for me Plex keeps failing this verification) you connect to Plex-server and every request you make gets forwarded to Plex-home and when you ask for media it gets routed through Plex-server. This is very different from exposing Plex-home directly to the internet, in order for someone online to access your Plex-home they need to have taken control of Plex-server and then they're limited by the API between those two (whichight be different from the Plex-home API) to try to escalate into your machine.

With Jellyfin there's no server side component, you access Jellyfin directly every time, so in order to access Jellyfin outside of your house it needs to be accessible for everyone. The closest you can come up with is using a third party authentication server, for example by having a VPS running Authentik/Authelia/etc and hosting Jellyfin behind that authentication. This gets you a similar level of security because someone would need to compromise your Auth and then your Jellyfin to get into your server. However I'm not sure Jellyfin clients would know how to handle a third party authentication service, and would probably just crap their pants and prevent you from logging in. You could still access it in a browser, but not on native clients like the one on your TV or Fire Stick.

If you don't have this VPS with authentication you're exposing Jellyfin directly to the internet, which means that any flaw in Jellyfin security immediately compromises your home server. And while I don't expect there to be many big or obvious flaws, there's a reason why stuff like Authelia or Authentik exists, and besides the convenience of a SSO they exist because proper authentication is hard and has many pitfalls, and they offer security in the knowledge that their main focus is authentication, whereas on most other services authentication is just one of the features they offer so it might not be as secure.