NoMachine stops accepting mouse and keyboard input

[webdawg]

So every once in a while for the past many years I connect to no machine.  This is Xorg – physical desktop control.

It would stop accepting inputs:  mouse – keyboard

I would restart w/ systemctl and nothing.  I recently did a few hour diagnosis session, and this fixes it:

PID=$(ps -o pid= -C nxnode.bin | tail -n1 | tr -d ' ')
echo "Tracing nxnode PID: $PID"
sudo timeout 6s strace -tt -e trace=openat -p "$PID" -o /tmp/nxnode.open || true
grep -F '/dev/uinput' /tmp/nxnode.open || echo "no /dev/uinput open() attempts recorded"

After attaching to the process, and letting it go – keyboard and mouse input springs to life.

Not sure of actual cause here – just know I have been dealing with this in Xorg for years.

[Britgirl]

Hi, we’ve not come across this. Can you send us the logs of the NoMachine host whose host you are connecting to?  You can extract them using the instructions here: https://kb.nomachine.com/DT08U00298 (Settings -> Server -> Security, Take logs)
You can attach them here or send them to forum[at]nomachine[dot]com. Please use the title of this topic as the subject of your email. Thanks!

[webdawg]

I can get logs.  I am close to being able to replicate this:

I remote in, input does not work.

I tried this:
PID=$(ps -o pid= -C nxnode.bin | tail -n1 | tr -d ' ')
echo "Tracing nxnode PID: $PID"
sudo timeout 6s strace -tt -e trace=openat -p "$PID" -o /tmp/nxnode.open || true
grep -F '/dev/uinput' /tmp/nxnode.open || echo "no /dev/uinput open() attempts recorded"

This stopped working in the erroring session.

This unstuck it:
DISPLAY=:0 xdotool mousemove 200 200 click 3

That stopped working.

Today I tried this:

DISPLAY=:0 xdotool mousemove 200 200 click 3

PID=$(ps -o pid= -C nxnode.bin | tail -n1 | tr -d ' ')

echo "Tracing nxnode PID: $PID"

sudo timeout 6s strace -tt -e trace=openat -p "$PID" -o /tmp/nxnode.open || true

DISPLAY=:0 xdotool mousemove 200 200 click 3

DISPLAY=:0 xdotool key ctrl+alt+t

DISPLAY=:0 xdotool type "da"

DISPLAY=:0 xdotool type "da"

DISPLAY=:0 xdotool type "da"

DISPLAY=:0 xdotool key ctrl+alt+t

DISPLAY=:0 xdotool type "da"

DISPLAY=:0 xdotool type "da"

DISPLAY=:0 xdotool type "da"

That worked twice.

What does fix it everytime is me coming to the physical ps/2 keyboard and typing.  Session unsticks everytime.

I sent the server logs to the email address.

[Britgirl]

Thanks for the logs. We’ll take a look and come back to you.

[Britgirl]

While we check, please ask to add this to /usr/NX/etc/node.cfg (and then restart the nxserver):

DisplayServerExtraOptions "-eventdelay 0"

It would help to narrow the investigation down, besides being a possible workaround.

[Author]

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