This is a text-only version of the following page on https://raymii.org:

This is a text-only version of the following page on https://raymii.org:
---
Title : Remote desktop on NetBSD with Xnest (no VNC)
Author : Remy van Elst
Date : 22-08-2021
URL : https://raymii.org/s/articles/Remote_desktop_on_NetBSD_with_Xnest_no_VNC.html
Format : Markdown/HTML
---

After I recently wrote about [NetBSD on the DEC Alpha CPU in QEMU][1], I
decided to play with NetBSD some more. One x86_64 virtual machine later, I'm
starting to appreciate the beauty and simplicity. Great documentation, both
online and via the manpages, low resource usage and boy oh boy does it feel
fast. But, you're not here for my love letter, you want to have a remote
desktop. In the [earlier][1] article, we set up VNC, both because it shows
you how to install packages and because native X11 crashes. In this article,
we are going to set up X11 forwarding via SSH, but with `Xnest` instead of
VNC. `Xnest` allows you to have a full desktop / window manager inside a
window. If you did a full install of NetBSD, then all you need is included on
the system, no need to install any packages. This is an advantage if you are
on an architecture that has no precompiled binary packages or if compiling
from source takes too long.

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Here is a screenshot of my native NetBSD X desktop, running the default `ctwm`
window manager, the `Clion` IDE, a web browser and my favorite game, `OpenTTD`:

![screenshot][2]

If you have XFCE installed, you can run a full desktop session as well:

![screenshot][3]

Other nostalgic desktop environments are available as well, like CDE and WindowMaker:

![screenshot][6]

Note that performance is slightly worse than with VNC and you might have some
artifacts when dragging windows around. I also have an issue where, once a
window manager is running, `xterm` will not start. If I start `xterm` before
I start `ctwm` or `xfce` it runs fine. Here is a screenshot of the artifacts
after dragging a window around. They're gone when you refresh that screen area,
for example, by dragging another window around over that affected area:

![screenshot][8]

In this article, the terms `server` and `NetBSD host` are used interchangeably,
they both mean the NetBSD machine on which you want to run the GUI. The term
`client` means the machine you forward the desktop to, the machine from which
you SSH into the NetBSD server. On the `client`, the window is displayed, but
the actual X server / GUI is coming from the `server`.

### Setup X11 forwarding via SSH

This part assumes you installed NetBSD with X11 via the installer. That way,
both `Xnest` and the default window manager, `ctwm` are installed.

By default SSH does not allow X11 forwarding. Edit the following file on the
NetBSDS server to allow X11 forwarding:

vi /etc/ssh/sshd_config

Add the following line (or uncomment/change it) to allow X forwarding system
wide for all users:

X11Forwarding yes

You can also add a `Match` block to enable X11 for just one user:

Match User remy
X11Forwarding yes

Restart the ssh server to make this new setting active:

service sshd restart

Test it out with the following SSH command on your client machine:

ssh -Y [email protected]

After logging in to your NetBSD machine, start a terminal:

xterm

It should pop up on your client (the one you used to SSH into the NetBSD
server). I'm using the `-Y` flag instead of the `-X` flag because it saves
you fiddling with `xauth`.

Continue on to the next section to use an actual window manager inside a
window (nested X, or, a better name, `Xnest`).

### Xnest and ctwm

The next section assumes you are logged in via SSH to the NetBSD server with the `-Y` flag.
The manpage describes what `Xnest` is very well:

> Xnest is both an X client and an X server. Xnest is a client of the real
server which manages windows and graphics requests on its behalf. Xnest is
a server to its own clients. Xnest manages windows and graphics requests on
their behalf. To these clients, Xnest appears to be a conventional
server.

Start Xnest with the following options on the NetBSD machine:

Xnest :1 -ac -once &

- `:1`: The display which the new nested X server will use.
- `-ac`: disable access control restrictions
- `-once`: Terminate server after one session
- ` &`:

Start the default window manager `ctwm`, with our new display as an option:

ctwm -display :1

This is what you should see in the `Xnest` window on your client:

![screenshot][2]

I have an error when launching `xterm` (or `xcalc`) once `Xnest` is running:

X Error of failed request: BadAlloc (insufficient resources for operation)
Major opcode of failed request: 45 (X_OpenFont)
Serial number of failed request: 12
Current serial number in output stream: 13

As stated before, when I launch `xterm` directly, it works, when in `Xnest`, it fails.
Tried setting up the `xfs` (x font server) and all kinds of `xset +fp` variants to inform
Xnest of fonts. The default font path has all files required and my client machine also
has the same files in the same paths (the xnest manpage mentions this). Not being able to
run xterm is annoying, but since I have xfce installed, I can run `xfce-terminal` or
execute commands right on the SSH session shell.

Do note that you do not have to use `$DISPLAY=:1`. Before starting Xnest you can
query the current `DISPLAY` variable (that SSH X forwarding uses):

echo $DISPLAY

Output:

localhost:10.0

Since we've started SSH with `-Y`, we can use `:10` as the display variable
in `Xnest`, ignoring the `localhost` part:

Xnest -ac -once :10 &

Now you do not need to specify `-display :1` or export a new display variable
in your terminal. I'm used to explicitly specifying one, which is why I do it
that way in this guide.

### XFCE

If you have a network connection and binary packages available, you can
install XFCE, a modern desktop. It works quite well when forwarded via Xnest.
This section contains a mini XFCE install guide as a bonus. Make sure you
have `pkgin`, the binary package manager, installed and use `pkgin` to
install `xfce` plus some dependencies:

pkgin install xfce fam dbus

`xfce` is a group of packages. Once all of them are installed, copy the
example dbus startup script to the required location:

cp /usr/pkg/share/examples/rc.d/dbus /etc/rc.d/dbus

Edit `/etc/rc.conf` and add:

dbus=YES

Start `dbus`:

service dbus start

You only have to start dbus on this session, after a reboot it will be started
automatically.

Repeat the same for `fam` and `rpcbind`, also required for XFCE:

cp /usr/pkg/share/examples/rc.d/famd /etc/rc.d/
echo rpcbind=YES >> /etc/rc.conf
echo famd=YES >> /etc/rc.conf
service rpcbind start
service famd start

Make sure you have an empty `Xnest` session started. Export the `DISPLAY` variable
so XFCE knows in which X session it should run:

export DISPLAY=:1

Start XFCE in that new `Xnest` session:

dbus-launch /usr/pkg/bin/xfce4-session

It takes a few seconds to load. The background image took a bit longer for me
than the rest of the session. Here is how it should look:

![screenshot][3]

Other window managers are available as well. I've tried `fluxbox` and
`lumina-desktop`, the latter taking a while to compile. `windowmaker` is fun
to play with as well. Here is a screenshot after installing the
`windowmaker-desktop` meta-package and running `wmaker -display :1` to start:

![screenshot][6]

If you're feeling really nostalgic, `CDE`, the [Common Desktop Environment][4]
is also [available for NetBSD][5]. Astr0baby has a [guide to run CDE on NetBSD][7]
on the Pinebook Pro.

[1]: /s/articles/NetBSD_on_QEMU_Alpha.html
[2]: /s/inc/img/netbsd-xnest-1.png
[3]: /s/inc/img/netbsd-xnest-2.png
[4]: /s/blog/The_Common_Desktop_Environment_CDE_is_still_developed_in_2021.html
[5]: https://sourceforge.net/p/cdesktopenv/wiki/NetBSD/
[6]: /s/inc/img/netbsd-xnest-3.png
[7]: http://web.archive.org/web/20210821210536/https://astr0baby.wordpress.com/2020/05/03/cde-common-desktop-environment-on-netbsd-ebvarm-pinebook/
[8]: /s/inc/img/netbsd-xnest-4.png

---

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