# Remote visualization using VNC
## Short guide
---
1. Connect to **viz**:
ssh uni-ID@viz.hpc.taltech.ee
2. Start VNC on **viz** by command:
vncserver -geometry 1265x980
3. Open a second connection to **viz**:
ssh -L 59XX:localhost:50XX uni-ID@viz.hpc.taltech.ee
where `XX` is the display number that appear after giving `vncserver` command.
***NB!*** _`XX` is always the number of two digits (e.g. `01` for `:1`)_
4. On your desktop start a vncviewer
vncviewer :XX
where `XX` is the display number
5. **Stop the vncserver!!!** on **viz** by command:
vncserver -kill :XX
## Get started
---
### Software recommended to use
Virtual Network Computing (VNC) is a graphical desktop-sharing system to remotely control another computer.
The client (your desktop) computer needs a vncviewer
- **Linux:** [xtigervncviewer](https://command-not-found.com/xtigervncviewer)
- **Windows:** TigerVNCviewer: [vncviewer64-1.12.0.exe](https://sourceforge.net/projects/tigervnc/files/stable/1.12.0/vncviewer64-1.12.0.exe/download)
- **Mac:** [VNC Viewer](https://www.realvnc.com/en/connect/download/viewer/)
### First time use
On the first start, VNC asks to specify a password to connect to the server, choose a secure one, which does not match your HPC password because VNC connections are not encrypted!
## VNC Long version
---
VNC should be run firstly at **viz** node of HPC and after at user's computer.
1. Connect to **viz** by command:
ssh uni-ID@viz.hpc.taltech.ee
if this command does not work try to connect through jump host:
ssh -J uni-ID@base.hpc.taltech.ee uni-ID@viz
***NB!*** _Connection to **viz** can be done ***only*** with SSH keys. SSH key generation guide is [here](../ssh.md)._
***NB!*** _To use **viz** the SSH key must be added to the **base** node._
On Mac and Linux this can be done by command:
ssh-copy-id Uni-ID@base.hpc.taltech.ee
After about an hour, when the automatic script has synced the files, and you can use **viz**.
2. On **viz** start the VNC server. Depending on which VNC client user has, one of those commands should be given:
vncserver -geometry 1265x980
and for Tiger VNC:
tigervncserver -geometry 1280x1024
It is recommended to specify window size as well by `-geometry` flag, since changing the resolution of the remote desktop (= window size) at runtime can have undesired effects.
3. The output in the terminal will show on which display VNC is running.
see second line `desktop at :8`, where `:8` is the display number -- further `XX`.
4. Open a second connection to **viz** (in new terminal) and give the command:
ssh -L 59XX:localhost:50XX uni-ID@viz.hpc.taltech.ee
where `XX` is the display number as two digits (e.g. `01` for `:1`)
***NB!*** _If you were connected through jump host this command should be given:_
ssh -J Uni-ID@base.hpc.taltech.ee -L 59XX:127.0.0.1:59XX Uni-ID@viz
4. On **your desktop** start a VNC viewer. If you do it from terminal -- give one of these command depending on which VNC viewer you have:
vncviewer :XX
or
xtigervncviewer localhost:XX
where `XX` is the number from above. On Windows (depending on the VNC-client) the address to connect to could be `localhost::50XX` (again, the `XX` stands for the display/port as specified before).
If you use graphical interface - specify localhost - in the corresponding field (line in the top) and click bottom "Continue".
Type password.
If you see monochromic field and can not start a session, it mean that you to set up your VNC session.[First time use](https://hpc.pages.taltech.ee/user-guides-new4/visualization/vnc.html#first-time-use).
If you see terminal - then everything is done correctly and you can start working. Within the session window, you can start any program from the terminal or using the menus of the window manager.
**Viz** has module system. Most of the modules are needed to be loaded unless the manual says they are native.
Before loading modules, the source must be specified:
source /usr/share/lmod/6.6/init/bash
module use /gpfs/mariana/modules/system
followed by two commands to load the modules. The first one loads ***viz-spack*** or ***viz module,*** depending on program installation type, and the second command loads the program itself.
For example:
module load viz-spack
module load jmol
In case of native program only the command that calls this program is needed.
rasmol
or
paraview
## Correct termination
---
In is very important to finish session correctly! Since if you do not do it - session continue to run even if you close session on your computer.
To stop VNC session give on **viz** one of these commands:
vncserver -kill :XX
or
tigervncserver -kill :XX
where `XX` is the display number.
Running sessions can be checked by command:
vncserver -list
## Setting up VNC session
---
It is impossible to work with VNC without setting it. To do this give the following commands from home catalogue on **base** or **viz**:
cat < .xsession
xterm &
fvwm2
EOT
This will configure automatic startup of `xterm` and `fvwm2` window manager. Alternatively, user can use other window managers: more desktop-like -- `fluxbox`, `awesome` or `jwm` or tiling -- `i3`, `xmonad` or `tritium`. To do this, the corresponding line must be added to `.xsession` file by command:
echo "fluxbox" >> .xsession
The same way `.vnc/xstartup` can be configured in case user wants to apply special settings exactly to VNC visualisation.