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remove vnc and x2go in favor of ood
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‎mkdocs/docs/HPC/VNC.md‎

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# Graphical applications with VNC
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{% if site == gent %}
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**VNC is still available at UGent site but we encourage our users to replace VNC by X2Go client**.
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Please see [Graphical applications with X2Go](../x2go/#graphical-applications-with-x2go) for more information.
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{% endif %}
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Virtual Network Computing is a graphical desktop sharing system that
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enables you to interact with graphical software running on the HPC
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infrastructure from your own computer.
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**Please carefully follow the instructions below, since the procedure to connect to a VNC server running on the HPC infrastructure is not trivial, due to security constraints.**
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## Starting a VNC server
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First login on the login node (see [First time connection to the HPC infrastructure](../connecting/#first-time-connection-to-the-hpc-infrastructure), then start `vncserver` with:
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```
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$ vncserver -geometry 1920x1080 -localhost
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You will require a password to access your desktops.
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Password: <enter a secure password>
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Verify: <enter the same password>
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Would you like to enter a view-only password (y/n)? n
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A view-only password is not used
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New '{{loginhost}}:6 ({{userid}})' desktop is {{loginhost}}:6
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Creating default startup script {{homedir}}.vnc/xstartup
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Creating default config {{homedir}}.vnc/config
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Starting applications specified in {{homedir}}.vnc/xstartup
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Log file is {{homedir}}.vnc/{{loginhost}}:6.log
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```
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**When prompted for a password, make sure to enter a secure password: if someone can guess your password, they will be able to do anything with your account you can!**
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Note down the details in bold: the hostname (in the example: `{{loginhost}}`) and the
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(partial) port number (in the example: `6`).
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It's important to remember that VNC sessions are permanent. They survive
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network problems and (unintended) connection loss. This means you can
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logout and go home without a problem (like the terminal equivalent
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`screen` or `tmux`). This also means you don't have to start `vncserver`
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each time you want to connect.
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## List running VNC servers
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You can get a list of running VNC servers on a node with
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```
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$ vncserver -list
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TigerVNC server sessions:
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X DISPLAY # PROCESS ID
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:6 30713
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```
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This only displays the running VNC servers on **the login node you run the command on**.
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To see what login nodes you are running a VNC server on, you can run the
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`ls .vnc/*.pid` command in your home directory: the files shown have the
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hostname of the login node in the filename:
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```
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$ cd $HOME
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$ ls .vnc/*.pid
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.vnc/{{loginhost}}:6.pid
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.vnc/{{altloginhost}}:8.pid
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```
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This shows that there is a VNC server running on `{{loginhost}}` on port 5906 and
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another one running `{{altloginhost}}` on port 5908 (see also [Determining the source/destination port](./#determining-the-sourcedestination-port)).
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## Connecting to a VNC server
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The VNC server runs on a (in the example above, on `{{loginhost}}`).
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In order to access your VNC server, you will need to set up an SSH
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tunnel from your workstation to this login node (see [Setting up the SSH tunnel(s)](./#setting-up-the-ssh-tunnels)).
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Login nodes are rebooted from time to time. You can check that the VNC
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server is still running in the same node by executing `vncserver -list`
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(see also
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[List running VNC servers](./#list-running-vnc-servers)). If you get an empty list, it means that there is no VNC
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server running on the login node.
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**To set up the SSH tunnel required to connect to your VNC server, you will need to port forward the VNC port to your workstation.**
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The *host* is `localhost`, which means "your own computer": we set up an
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SSH tunnel that connects the VNC port on the login node to the same port
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on your local computer.
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### Determining the source/destination port
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The *destination port* is the port on which the VNC server is running
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(on the login node), which is **the sum of `5900` and the partial port number** we noted down earlier (`6`); in the
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running example, that is `5906`.
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The *source port* is the port you will be connecting to with your VNC
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client on your workstation. Although you can use any (free) port for
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this, we strongly recommend to use the **same value as the destination port**.
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So, in our running example, both the source and destination ports are
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`5906`.
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### Picking an intermediate port to connect to the right login node
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In general, you have no control over which login node you will be on
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when setting up the SSH tunnel from your workstation to `{{loginnode}}` (see [Setting up the SSH tunnel(s)](./#setting-up-the-ssh-tunnels)).
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If the login node you end up on is a different one than the one where
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your VNC server is running (i.e., `{{altloginhost}}` rather than `{{loginhost}}` in our running
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example), you need to create a ***second* SSH tunnel** on the login node you are connected to,
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in order to "patch through" to the correct port on the login node
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where your VNC server is running.
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In the remainder of these instructions, we will assume that we are
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indeed connected to a different login node. Following these instructions
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should always work, even if you happen to be connected to the correct
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login node.
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To set up the second SSH tunnel, you need to **pick an (unused) port on the login node you are connected to**, which will be used as an
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*intermediate* port.
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Now we have a chicken-egg situation: you need to pick a port before
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setting up the SSH tunnel from your workstation to `{{loginhost}}`, but only after
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starting the SSH tunnel will you be able to determine whether the port
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you picked is actually free or not...
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In practice, if you **pick a *random* number between $10000$ and $30000$**, you have a good chance that the port will not be
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used yet.
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We will proceed with $12345$ as intermediate port, but **you should pick another value that other people are not likely to pick**. If you need
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some inspiration, run the following command on a Linux server (for
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example on a login node): `echo $RANDOM` (but do not use a value lower
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than $1025$).
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### Setting up the SSH tunnel(s)
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#### Setting up the first SSH tunnel from your workstation to {{loginnode}}
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First, we will set up the SSH tunnel from our workstation to .
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Use the settings specified in the sections above:
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- *source port*: the port on which the VNC server is running (see [Determining the source/destination port](./#determining-the-sourcedestination-port));
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- *destination host*: `localhost`;
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- *destination port*: use the intermediate port you picked (see [Picking an intermediate port to connect to the right login node](./#picking-an-intermediate-port-to-connect-to-the-right-login-node))
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{% if OS == windows %}
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See for detailed information on how to configure PuTTY to set up the SSH
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tunnel, by entering the settings in the and fields in [SSH tunnel](../running_interactive_jobs/#ssh-tunnel).
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{% else %}
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Execute the following command to set up the SSH tunnel.
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```
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ssh -L 5906:localhost:12345 {{userid}}@{{loginnode}}
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```
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**Replace the source port `5906`, destination port `12345` and user ID {{userid}} with your own!**
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{% endif %}
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With this, we have forwarded port `5906` on our workstation to port
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`12345` on the login node we are connected to.
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**Again, do *not* use `12345` as destination port, as this port will most likely be used by somebody else already; replace it with a port number you picked yourself, which is unlikely to be used already (see [Picking an intermediate port to connect to the right login node](./#picking-an-intermediate-port-to-connect-to-the-right-login-node)).**
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#### Checking whether the intermediate port is available
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Before continuing, it's good to check whether the intermediate port that
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you have picked is actually still available (see [Picking an intermediate port to connect to the right login node](./#picking-an-intermediate-port-to-connect-to-the-right-login-node)).
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You can check using the following command (**do not forget to replace `12345` the value you picked for your intermediate port):
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```
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netstat -an | grep -i listen | grep tcp | grep 12345
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```
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If you see no matching lines, then the port you picked is still
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available, and you can continue.
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If you see one or more matching lines as shown below,
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**you must disconnect the first SSH tunnel, pick a different intermediate port, and set up the first SSH tunnel again using the new value**.
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```
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$ netstat -an | grep -i listen | grep tcp | grep 12345
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tcp 0 0 0.0.0.0:12345 0.0.0.0:* LISTEN
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tcp6 0 0 :::12345 :::* LISTEN
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$
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```
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#### Setting up the second SSH tunnel to the correct login node
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In the session on the login node you created by setting up an SSH tunnel
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from your workstation to `{{loginnode}}`, you now need to set up the second SSH
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tunnel to "patch through" to the login node where your VNC server is
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running (`{{loginhost}}` in our running example, see [Starting a VNC server](./#starting-a-vnc-server)).
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To do this, run the following command:
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```
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$ ssh -L 12345:localhost:5906 {{loginhost}}
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$ hostname
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{{loginhost}}
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```
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With this, we are forwarding port `12345` on the login node we are
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connected to (which is referred to as `localhost`) through to port
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`5906` on our target login node (`{{loginhost}}`).
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Combined with the first SSH tunnel, port `5906` on our workstation is
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now connected to port `5906` on the login node where our VNC server is
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running (via the intermediate port `12345` on the login node we ended up
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one with the first SSH tunnel).
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**Do not forget to change the intermediate port (`12345`), destination port (`5906`),
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and hostname of the login node (`{{loginhost}}`) in the command shown above!
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As shown above, you can check again using the `hostname` command whether
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you are indeed connected to the right login node. If so, you can go
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ahead and connect to your VNC server (see [Connecting using a VNC client](./#connecting-using-a-vnc-client)).
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### Connecting using a VNC client
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{% if OS == windows %}
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You can download a free VNC client from
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<https://sourceforge.net/projects/turbovnc/files/>. You can download the
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latest version by clicking the top-most folder that has a version number
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in it that doesn't also have `beta` in the version. Then download a file
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that looks like `TurboVNC64-2.1.2.exe` (the version number can be
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different, but the `64` should be in the filename) and execute it.
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{% endif %}
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{% if OS == macos %}
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You can download a free VNC client from
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<https://sourceforge.net/projects/turbovnc/files/>. You can download the
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latest version by clicking the top-most folder that has a version number
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in it that doesn't also have `beta` in the version. Then download a file
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ending in `TurboVNC64-2.1.2.dmg` (the version number can be different)
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and execute it.
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{% endif %}
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{% if OS == linux %}
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Download and setup a VNC client. A good choice is
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`tigervnc`. You can start it with the `vncviewer` command.
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{% endif %}
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Now start your VNC client and connect to `localhost:5906`. **Make sure you replace the port number `5906` with your own destination port (see [Determining the source/destination port](./#determining-the-sourcedestination-port)).
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When prompted for a password, use the password you used to setup the VNC
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server.
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When prompted for default or empty panel, choose default.
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If you have an empty panel, you can reset your settings with the
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following commands:
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```
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xfce4-panel --quit ; pkill xfconfd
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mkdir ~/.oldxfcesettings
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mv ~/.config/xfce4 ~/.oldxfcesettings
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xfce4-panel
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```
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## Stopping the VNC server
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The VNC server can be killed by running
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```
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vncserver -kill :6
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```
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where `6` is the port number we noted down earlier. If you forgot, you
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can get it with `vncserver -list` (see [List running VNC servers](./#list-running-vnc-servers)).
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## I forgot the password, what now?
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You can reset the password by first stopping the VNC server (see ), then
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removing the `.vnc/passwd` file (with `rm .vnc/passwd`) and then
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starting the VNC server again (see [Starting a VNC server](./#starting-a-vnc-server)).
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We strongly encourage the use of the [web portal](web_portal.md) for graphical use cases.

‎mkdocs/docs/HPC/account.md‎

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buttons ++"Save public key"++ and ++"Save private key"++. We recommend using the name **"id_rsa.pub"** for the public key, and
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**"id_rsa.ppk"** for the private key.
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{%- if site == gent %}
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6. Finally, save an "OpenSSH" version of your private key (in
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particular for later "X2Go" usage, see [x2go]()) by entering the
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"Conversions" menu and selecting "Export OpenSSH key" (do **not** select the
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"force new file format" variant). Save the file in the same location
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as in the previous step with filename **"id_rsa"**. (If there is no
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"Conversions" menu, you must update your "puttygen" version. If you
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want to do this conversion afterwards, you can start with loading an
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existing "id_rsa.ppk" and only do this conversions export.)
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![image](img/ch2-puttygen-conversions-export_openssh.png){ style="display: block; margin: 0 auto" }
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{%- endif %}
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If you use another program to generate a key pair, please remember that
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they need to be in the OpenSSH format to access the {{ hpc }} clusters.
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{% endif %}

‎mkdocs/docs/HPC/troubleshooting.md‎

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![image](img/putty_security_alert.jpg)
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{% if site == gent %}
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If you use X2Go client, you might get one of the following fingerprints:
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{{xtwogoshaone}}
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**If you get a message "Host key for server changed", do not click "No" until you verified the fingerprint.**
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If the fingerprint matches, click "No", and in the next pop-up screen ("if you accept the new host key..."), press "Yes".
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If it doesn't, or you are in doubt, take a screenshot, press "Yes" and contact {{hpcinfo}}.
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{% endif %}
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{% endif %}
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## DOS/Windows text format
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```
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{% endif %}
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{% if site == gent %}
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{% if OS == macos %}
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If you use X2Go, then you might get another fingerprint, then make sure that the fingerprint
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is displayed is one of the following ones:
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{{xtwogoshaone}}
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{% endif %}
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{% endif %}
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If it does, type ***yes***. If it doesn't, please contact support: {{hpcinfo}}.
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{% if OS != (linux or macos) %}
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{% include "../macros/firsttimeconnection.md" %}
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{% if site == gent %}
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If you use X2Go, then you might get another fingerprint, then make sure that the fingerprint
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is displayed is one of the following ones:
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{% endif %}
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{% endif %}
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## Memory limits

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