Xpra - X Persistent Remote Applications

	Xpra (X Persistent Remote Applications) ... is a remote display solution for forwarding applications and desktop screens. Applications forwarded by Xpra appear on the local desktop as normal windows (seemless mode), rather than being all "trapped in a box together" (full desktop mode) like with VNC. Xpra uses a custom protocol that is self-tuning and relatively latency-insensitive, and thus is usable also over worse links. Xpra allows disconnection and reconnection without disrupting the forwarded application. Xpra is an open-source software for multiple platforms (Linux, Windows, MaxOS, etc.). ​http://www.xpra.org ​https://en.wikipedia.org/wiki/Xpra Download: ​Linux (various distributions) ​MacOSX (>=10.5) ​Windows (>=XP)

Preparation

Authentication

Xpra must communicate with JURECA via Secure Shell (SSH).
Authentication must be passwordless using a SSH key-pair.
Please test your system before you proceed.

Execute the command with your JURECA-userid on your local workstation.
It must return the word 'success' for a successful SSH connection to JURECAVIS.

Linux/MacOSX:
ssh <YOUR-USERID>@jurecavis.fz-juelich.de echo "success"

Windows/Putty:
"C:\Program Files (x86)\PuTTY\plink.exe" -ssh <YOUR-USERID>@jurecavis.fz-juelich.de echo "success"
Ensure you have loaded your key in PuTTY´s SSH key agent called Pagent before!

Installation

Before you use Xpra for the first time you have to install it on your workstation:

• download & install Xpra (​http://www.xpra.org)

Using Xpra requires three general steps.

1. Start Application as Xpra-session on a JURECAVIS node.
2. Start Xpra-client locally on your workstation.
3. Connect with Xpra-client to Xpra-session on JURECACVIS node.

1. Start Application

ssh <USERID>@jurecavis01.fz-juelich.de

module load Stages/Devel
module load GCCcore/.5.4.0
module load Xpra

xpra start :100 --start-child=xterm

2. Start Xpra locally

3. Connect

<TO BE CONTINUED ... PLEASE COME BACK LATER>

Background Information

Authentication:

Xpra must communicate with JURECA via Secure Shell (SSH).
It is mandatory that JURECA trusts Xpra and is 100% sure
that the incoming connection is by a certain user and no none else.

Hence, each new SSH connections starts with an authentification procedure.
SSH supports different authentification methods, but not all are available on any site.
Xpra must be used with the most secure Public-Key Authentification (PKA) to connect to JURECA.

PKA is based on a SSH key-pair with a private key and a public key.
The private key never leaves the local machine and the public key must be installed on the remote machine.
Anyone who knows the private key can now connect to the remote machine.

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any feedback welcomed - h.zilken@…, j.goebbert@…