Xlibre [LWN.net]

Xlibre

Posted Jun 14, 2025 12:20 UTC (Sat) by eru (subscriber, #2753)
In reply to: Xlibre by numgmt
Parent article: Ubuntu 25.10 to drop support for GNOME on Xorg

Can you use it to "remote" the window of a single application, instead of a whole desktop? (This is one killer feature of X11 that I use almost every day).

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Xlibre

Posted Jun 14, 2025 13:07 UTC (Sat) by intelfx (subscriber, #130118) [Link] (12 responses)

> Can you use it to "remote" the window of a single application, instead of a whole desktop? (This is one killer feature of X11 that I use almost every day).

It's not really a killer feature of X11, not for a long time. Waypipe[1] exists and in practice works much better over mediocre links than X11 SSH forwarding, much less actual X11 network transparency, ever did.

[1]: https://gitlab.freedesktop.org/mstoeckl/waypipe

Xlibre

Posted Jun 16, 2025 10:30 UTC (Mon) by eru (subscriber, #2753) [Link] (11 responses)

Thanks, good to know for the dreaded day I cannot use X11 any more. But this seems to be a complex 3.party program that might not be available in all installations at both the client and server ends. With X11, you get the functionality out of the box.

Xlibre

Posted Jun 16, 2025 11:03 UTC (Mon) by intelfx (subscriber, #130118) [Link] (10 responses)

> But this seems to be a complex 3.party program that might not be available in all installations at both the client and server ends. With X11, you get the functionality out of the box.

The thing is, you don't.

`ssh -X` is as much of a third-party program as `waypipe` is.

And in the off-chance if you're **actually** talking about X11's **actual** network transparency, i.e., `DISPLAY=somehost:0`, then that stopped working satisfactorily even longer ago than `ssh -X` (unless you limit yourself to Motif and Tk, I guess).

Xlibre

Posted Jun 16, 2025 12:37 UTC (Mon) by eru (subscriber, #2753) [Link] (4 responses)

ssh is nowadays a common piece of infrastructure with multiple uses, so it can be assumed to be available. Rather like sh, ls, cat etc. Waypipe is specialised, complex, and has a ton of dependencies. X11 remoting has worked well for my needs, obviously I am not running games or video editors through it. Anyway, I'll stop grumbling now.

Xlibre

Posted Jun 16, 2025 13:48 UTC (Mon) by pizza (subscriber, #46) [Link] (2 responses)

> ssh is nowadays a common piece of infrastructure with multiple uses, so it can be assumed to be available. Rather like sh, ls, cat etc. Waypipe is specialised, complex, and has a ton of dependencies.

So... [random X11 application] isn't specialized, complex, with a ton of dependencies? I mean, if you're trying to run an X11 application remotely, you're going to need at minimum full client xlib+whatever else on one side, and an running xserver+whatever else on the other side. In other words, by definition, both sides need to have everything necessary to run said application, and *all of it* is outside the scope of what ssh provides (ie a forwarded TCP connection)

Along that line, nothing prevents [Portable] OpenSSH adding support for wrapping waypipe, eg by adding -W and associated configuration options. There's plenty of precedence, not just with X11 (via -X) and various authentication agents but also things like scp/sftp which work by forking off separate executables (on both sides) and shuffling data between the two.

(I would also point out that openssh's -X option claims to support interacting with X11 "Security extensions" by default; I don't know exactly what that entails under the hood but it's clearly more than just setting up a port forward and setting $DISPLAY on the remote side)

Xlibre

Posted Jun 17, 2025 1:50 UTC (Tue) by raven667 (subscriber, #5198) [Link] (1 responses)

> openssh's -X option claims to support interacting with X11 "Security extensions"

I think this refers to running xauth to set an MIT Magic Cookie value in ~/.Xauthority which is like an API token that prevents other users on the same system from just connecting to your forwarded X11 port on localhost and rickrolling (at best) your screen.

Xlibre

Posted Jun 23, 2025 8:29 UTC (Mon) by cortana (subscriber, #24596) [Link]

The SECURITY extension allows certain clients to be marked as "untrusted" which prevents them from being able to spy on input events, take screenshots of other clients and so on.

Unfortunately many clients break completely under such restrictions. For many years, Debian patched OpenSSH to disable the use of the SECURITY extension by deafult. Nowadays I think the situation is a bit better but I've not used X11 forwarding for a long time so haven't verified.

Xlibre

Posted Jun 16, 2025 16:11 UTC (Mon) by intelfx (subscriber, #130118) [Link]

Of course, OpenSSH (not just ssh, but very specifically OpenSSH) is going to be more widely available than Waypipe, simply by virtue of being an older and more established technology (as well as historical precedent). However, we weren't discussing that:

>> <...> With X11, you get the functionality out of the box. <...>

What we were discussing is that both are structurally *third-party software*. There is nothing conceptually "out-of-the-box" about `ssh -X`, not any more than Waypipe. Whether the latter is significantly more specialized and complex is in the eye of the beholder.

> X11 remoting has worked well for my needs

Nobody was disputing that. We were talking about whether it actually is a "killer feature".

Xlibre

Posted Jun 16, 2025 13:13 UTC (Mon) by paulj (subscriber, #341) [Link] (4 responses)

Is there a replacement for XPRA?

I still use ssh -X for some very graphically-limited apps - xterm mostly - but for anything using a modern toolkit you really need XPRA to get good performance. And the persistence / immunity to transient network issues/moves is a nice bonus in some cases; and absolutely essential in other cases. E.g., I use xpra to access the same instance of an app between work and home, without having to restart the app and my flow in it.

Xlibre

Posted Jun 16, 2025 16:13 UTC (Mon) by intelfx (subscriber, #130118) [Link]

> Is there a replacement for XPRA?
>
> I still use ssh -X for some very graphically-limited apps - xterm mostly - but for anything using a modern toolkit you really need XPRA to get good performance.

Waypipe does not need anything like Xpra to get good performance; you get it by default.

> And the persistence / immunity to transient network issues/moves is a nice bonus in some cases

There is no persistence, however. Earlier versions of Waypipe had rudimentary support for reconnection, but it was since dropped — not sure why, perhaps lack of interest on the sole developer's part.

Xlibre

Posted Jun 17, 2025 1:58 UTC (Tue) by raven667 (subscriber, #5198) [Link]

I think in other cases with Wayland the compositors just support RDP or VNC output, VNC being slow but simple and RDP working well over WAN links with various acceleration options available in the protocol (maybe including just encoding as a video stream, same as any modern WebRTC video conferencing and desktop sharing system) if the server takes advantage of them, degrading to something like VNC if not. I think Waypipe is more for the single-app forwarding use case (although I believe RDP protocol is capable of single-app forwarding), and I'd be super happy when it gets integrated directly into Portable OpenSSH or as a Linux-distro maintained extension for the popular platforms.

Xlibre

Posted Jun 17, 2025 8:50 UTC (Tue) by vasvir (subscriber, #92389) [Link] (1 responses)

Well there is wprs (xpra for wayland): https://github.com/wayland-transpositor/wprs

I use it as my daily driver and while it has its issues it is workable...

I have filed some bug reports and some of them have been fixed.

Xlibre

Posted Jun 17, 2025 9:50 UTC (Tue) by paulj (subscriber, #341) [Link]

Great news, thanks for the link!

Xlibre

Posted Jun 23, 2025 4:20 UTC (Mon) by wperkins (guest, #767) [Link]

Yeah! This is one feature that I have used every day for many years!