nxnode process running even after logout

[Frank Steiner]

Hi,

after upgrading to NoMachine 9.0 we see that for every user who is logging in physically to a machine (not via nx) a nxnode process is started:

root     21834  0.0  0.0  21052  6364 ?        S<   11:34   0:00 /usr/NX/bin/nxexec –node /usr/NX/bin/nxexec –nopam –user blabla –priority realtime –mode 0 –pid 38
blabla      21846  0.1  0.1 1647552 79324 ?       S<l  11:34   0:00 /usr/NX/bin/nxnode.bin

That process stays even when user logs out on the machine (with no remote nx access ever done) and it cannot be killed anymore. After doing “pkill -9 -u blabla” these two processes come back immediately.

Why is that? Why is a process started for the local user even if the machine is not accessed by nx at all? Shouldn’t that be spawned only when nx tries to access the machine?

And why do these processes keep running after the user logs out, and why can they not be killed?

Running NoMachine-9.0.188-11.x86_64 on SuSE Linux Enterprise Desktop 15 sp6 (aka leap 15.6).

Thanks a lot!

[Bilbotine]

Hi Frank,

NoMachine starts an nxnode process as every user, to be able to manage his physical session.

When a user physically logs out from the desktop, and if the desktop is on login window, nxnode will be running with for example ( gdm, ssdm, or lightdm ).

[Frank Steiner]

No, that’s not true: We are using kdm as login manager. Restart the host and nx is running just as user root and nx. Then a user logs in => a nxexec process owned by root with “–user <username>” is running and a nxnode.bin process owned by the user.

But after the logs out and the kdm mask is shown again, these nx process are still running and there is indeed an active session shown in “loginctl” for that logged-out user. Killing all processes for that user (as root with pkill -9 -u <user>) will restart the nx processes, i.e. there is a new “/usr/NX/bin/nxexec –node –user blabla…” owned by root and a new nxnode.bin owned by the user. The same when you kill the session with “loginctl kill-session …”, it will restart the nx processes for the logged-out user.

Only after another user logs in physically or connects to the kdm login mask with nx these processes will be started for this new user and the processes of the previous user will be killed.

Thus,  the nx processes are not ended when the user logs out, they keep running until another user logs in and an active login session will be shown in loginctl until then.

Keeping an active login session for user although he has logged out from the system is definitely a bad policy and should not happen. And it doesn’t make any sense.

[Bilbotine]

Hi Frank,

Thanks for this update; can you please send us logs with debug enabled to allow us to investigate deeper the problem ?

Follow the instructions in this document: https://kb.nomachine.com/DT07S00243. It’s valid for v9 as well.

If possible, restart the Linux machine before reproducing the issue, and wait a minute after the logout.

Kill the nxnode process, so we can see exactly why the process restarts.

Gather logs again, and send them to forum[at]nomachine[dot]com, making sure to reference the topic as the subject of the email.

[Author]

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