===== Tips'n'Tricks =====

Suggestions on how to make your life easier when using the cluster.

==== Tips to speedup logging in ====

One can speedup logging in by configuring her/his own ssh client. This will also help in scp-ing data to the cluster.


=== Particle Physics ===
My suggestion for Particle Physicists is to copy this piece of code inside their own ''.ssh/config'' file, and change it to your specific needs:

<code>
# access tjatte
Host tjatte
HostName tjatte.hep.lu.se
User <username on tjatte>
ForwardX11 yes

# directly access iridium gateway
Host iridiumgw
User <Username on iridium>
ForwardX11 yes
ProxyCommand ssh -q tjatte nc iridium.lunarc.lu.se 22

# directly access node X
Host nX.iridium
User <Username on iridium>
ForwardX11 yes
ProxyCommand ssh -q iridiumgw nc nX 22

# directly access node Y
Host nY.iridium
User <Username on iridium>
ForwardX11 yes
ProxyCommand ssh -q iridiumgw nc nY 22
</code>

**Example:** My user is ''florido''. In the template above, I would change all the ''<Username ...>'' to ''florido'', and ''nX'' to ''n12''. 

then to login to //n12// I will do: 

  ssh n12.iridium

And I will have to input 3 passwords: one for tjatte, one for the gateway and one for the node.

If you want to access the cluster nodes from outside the division, you must go through //teddi// and eventually copy the above setup in your home ''.ssh'' folder.
If you don't have an account on teddi or direct access to some other division machine, you should ask me to create one.

Where X and Y is the nodes you're allowed to run.

note that with the above you will be requested to input as many password as the number of machines in the connection. A way to ease this pain is to [[##speedup_login_by_using_ssh_keys|copy ssh keys to the nodes.]]
Copying ssh keys to the gateway is not (yet) possible, hence you will always need two passwords: one for the ssh key and one for the gateway.

=== Nuclear Physics ===

coming soon

== References: ==
  * http://sshmenu.sourceforge.net/articles/transparent-mulithop.html

==== Speedup login by using ssh keys ====
 
An alternative method of authenticating via ssh is by using ssh keys. It will ease the pain of writing many passwords. The only password you will need is to unlock your key.

:!: ** PLEASE DO NOT USE PASSWORDLESS KEYS. IT IS A GREAT SECURITY RISK. ** :!:

Read about them here:

https://wiki.archlinux.org/index.php/SSH_Keys


==== How not to loose all your job because you closed a ssh terminal ====

On the cluster one can use **byobu**. Byobu is an advanced text window manager that does little
better than screen (read below). To use it, just execute ''byobu'' at the command line. Offcial documentation can be found here: http://byobu.co/documentation.html

Use **screen**. //GNU screen// is an amazing tool that opens a remote terminal that is independent on your ssh connection. If the connection drops or you accidentally close the ssh window, it will still run your jobs on the cluster.

A quick and dirty tutorial can be read [[:it_tips#screen|here]], but there's plenty more on the internet.

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