Update IDRIS-infos.md

Author: brankarj

docs/clusters/IDRIS/IDRIS-infos.md

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+# Computing on Jean-Zay at IDRIS
+
+[IDRIS](http://www.idris.fr/docs/idris/missions)
+is the national computing center of the CNRS.
+Most information on the Jean-Zay machine can be found
+on the [Jean-Zay webpage at IDRIS](http://www.idris.fr/docs/jean-zay/nouvel-utilisateur/).
+The following gives only a brief summary of useful commands and procedures.
+
+## Getting an account
+
+Resources on the machine can be obtained by submitting a project to [eDARI](https://www.edari.fr/).
+
+A new account must be associated to one or more existing projects that received a resource allocation.
+Usually, new users join an existing project in IGE.
+This is achived by following the procedure described in the
+[eDARI portal](https://www.edari.fr/documentation/index.php/Documentation_compl%C3%A8te#ModalitesAccesCalculateurs).
+This requires filling forms with several information
+(personnal information, IP adresses of connections,...), 
+and getting approved by the IGE direction and IT department.
+
+A good practice is to provide at least two IP adresses to secure the connections,
+as for instance, the IP address of your personnal desktop,
+and at least one secured IGE server (one which is always alive).
+
+## Connecting to Jean-Zay
+
+You can only connect from one of the IP address provided to IDRIS.
+
+To connect by SSH through an IGE proxy server,
+edit the SSH configuration file (`~/.ssh/config`) to include:
+
+```
+Host ige-proxy
+     HostName address_of_the_IGE_proxy
+     User your_IGE_user_name
+
+Host jean-zay
+     ProxyJump ige-proxy
+     HostName jean-zay.idris.fr
+     User your_IDRIS_user_name
+```
+
+You can then connect to Jean-Zay with the command:
+
+```
+ssh jean-zay
+```
+
+Then you can share SSH keys (with the proxy and jean-zay)
+to avoid giving your password at each connection.
+
+