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Overview

When users are off-site or have slow internet connections, displaying graphics can be cumbersome.  PCDS has explored two solutions for this problem.  The first ("NX technology") gives the user a special remote desktop that is specifically designed to improve the performance of X11 graphics with slow connection speeds.  The second ("Virtual Box") allows the user to directly install the psana analysis environment on their Windows, Linux or MAC machine, so that LCLS data analysis (including graphics) can be done with no network connection (click here for information on the virtual box approach).

Access and support of LCLS's Nomachine service is intended for users involved with LCLS experiments or LCLS operation.

NX Technology

Nomachine NX is supported on Windows, MAC and Linux computers.

Use the following steps to setup the nomachine client:

1. Go here and download the appropriate client for your machine: https://drive.google.com/folderview?id=0B6-dVV3sxagXRWRQUGJHQ0ZLemc&usp=sharing_eid&invite=CJyJpdQI#list. The current tested version of Nomachine client 4.5.0.

  • MAC OS X: nomachine_4.5.x.dmg
  • RedHat Linux: nomachine_4.5.x.rpm  (64bit: x86_64.rpm, 32bit: i686.rpm)
  • Windows: nomachine_4.5.x.exe

* You could also download the latest version from www.nomachine.com and click on the 'Download now' button to download and install NoMachine client. However, there could be issue connecting to the server with the latest client. Ubuntu user should download the Debian version of the Nomachine client.

2. You will be prompted to setup a login profile when launching the NoMachine for the first time. Select the following options:

Protocol: SSH
Host: psnxserv.slac.stanford.edu,  Port: 22
Authentication: Use the NoMachine login (not the "system login"). Do not select 'Use an alternate server key'
Proxy: Don't use a proxy
Save as: Choose a name such as PSNXSERV. You could select 'Create a link on the desktop'
Select Done to finish the setup

3. You can hit Connect to start the connection

4. You will be prompted for your username and password. Enter your SLAC's Unix account and hit OK

5. Click on 'New virtual desktop or custom session'

6. Click 'Create a new GNOME virtual desktop'. You will be logged in after that

7. A useful feature: to get the the Access Menu: Ctrl-Alt-0 (windows) or Ctrl-Option-0 (mac) or click on upper right corner of the nomachine desktop screen to bring up the nomachine setting screen

To auto-resize windows resolution automatically (so you don't have to do the manual sizing below) go to the Access Menu in the previous line, and click Display -> ResizeRemoteScreen, then click "Done" and "Done" again to close the menu.

To resize the window manually: Click on System->Preferences->Display, select 'Resize remote screen'.  When you change the screen resolution you may not see enough of the window to click "Apply".  On MAC: To do this on the keyboard: hit "option-A". On Windows:  use "alt-A".

You can open a terminal with Applications->SystemTools->Terminal (or right-click on the desktop and select "Open in Terminal"

You can also disable nomachine service if you will not share out the desktop by disabling Nomachine service

Please contact pcds-help@slac.stanford.edu if you need more information or additional assistance with NoMachine NX.

 

Connection issue

If you are not able to connect to nomachine, check the followings:

  1. The server is setup to limit to four (4) connection attempt per minute, this is to discourage SSH brute force attempt for security purpose. If if it seems to take a long time to connect after you made multiple connection attempts quickly, you can just cancel out and try to log back into psnxserv in 1 to 2 minutes.
  2. If you have disconnected your session without logging out and try to reconnect, once you hit the connect button, you will see the following dialog box. You can create a new session by selecting 'Create a new desktop or custom session' or you can reconnect to your existing session. If the existing session failed to reconnect, you can right-lick on the icon representing your previous session and select Terminate session. And then click on 'Create a new desktop or custom session' and select 'Create a new virtual desktop' to click on continue.

Fix for NoMachine 4.3 on Windows/OSX

If you find that you cannot start a desktop session even after successfully authenticating from a Windows/OSX NoMachine client version 4.3+, try the following workaround:

In the file $USER/.nx/config/player.cfg, find the line:

<option key="SSH client mode" value="library" />

Change it to read:

<option key="SSH client mode" value="native" />

NOTE: You will be unable to resume any sessions from NX client 4.2 and earlier.

It is not yet known when this workaround could be undone (e.g. by upgrading the server software).

Reconnect "Black Screen" issues.

Sometimes users will find that they are unable to reconnect to an existing session, and are shown only a blank screen.  We do not yet understand this issue, so our solution is to terminate the user's existing sessions, and kill all the user's running processes on the Nomachine server.  The easiest way to fix this is to send a note to pcds-it-l@slac.stanford.edu and we will remove all old sessions and process.

It's also possible for users to deal with this themselves by ssh'ing to psnxserv and killing their own process.  Potentially useful commands follow:


Show all running user processes:
ps -f -u $USERNAME
 
Kill a specific process using its process ID (PID):
kill <PID>
 
Kill a specific process that doesn't want to die (and was not killed by> "kill <PID>"):
kill -9 <PID>
 
Kill *all* your jobs, including current ssh session, shell and the pkill command itself.
This is a quick way to get the easy kills--then ssh in again and> deal> with the hard-to-kill processes):
pkill -U $USERNAME

 

Note that you may have to reconnect after running "pkill" and may have to try a number of times (possibly using the -9 option, as shown with the "kill" command).

X11 fonts issues

*** Since we have upgraded to commercial version of Nomachine NX, installing x11 fonts is no longer needed. But the information could still be useful if we run our Nomachine backup server with Free NX.If you are receiving 'Font init failed' or there is certain fonts on the screen that you don't see when running EPICS (EDM) or LCLS home screen, you will need to install the appropriate font package for the OS that you are running:

 Windows: https://www.nomachine.com/download/download&id=16

MAC:  http://xquartz.macosforge.org/landing/

RHEL6:

yum install xorg-x11-fonts-"*"
ln -s /usr/share/X11/fonts/75dpi /etc/X11/fontpath.d/xorg-x11-fonts-75dpi

Ubuntu: You will need to install these packages: xfonts-base, xfonts-100dpi, xfonts-75dpi, xfonts-cyrillic

 

Resuming a nomachine connection

If you are not able to resume a NX Connection and you typically connect from multiple computers, be sure to use similar version of NoMachine client where you initiate the connection from. To check for Nomachine version, after you have launch Nomachine client, go to Preferences on top, then click on Updates, it will show you the version that you are running Nomachine on.

Other issues

If Ctrl-C (Ctrl-break) does not work on the Linux client, hit the Alt-Ctrl-C (Use it in proper sequence so hold down the key one at a time). WindowsKey-Ctrl-C, or turn on Caps Lock and hit Ctrl-C will also work.

 

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