Login to cluster

To login to the ALICE cluster you need to perform a hop-like login sequence. The two login nodes of the ALICE cluster cannot be accessed directly. One must first login to an ssh gateway and then to one of the login nodes. This mechanism is required for both login and file transfer operations. Below we describe how to perform these actions from Linux and Windows, separately.

Login to ALICE from Linux

The login nodes are named:

login1.alice.universiteitleiden.nl (10.161.0.12)
login2.alice.universiteitleiden.nl (10.162.0.13)

Setup ssh JUMP

In your linux server write in ~/.ssh/config for instance

Host hpc1 
  HostName login1.alice.universiteitleiden.nl
  User <USERNAME>
  ProxyJump <USERNAME>@ssh-gw.leidenuniv.nl:22
  
Host hpc2
  HostName login2.alice.universiteitleiden.nl
  User <USERNAME>
  ProxyJump <USERNAME>@ssh-gw.leidenuniv.nl:22

(Replace <USERNAME> by your own ULCN account name.)

If you want to look at the monitoring tools that are running on the management node too, you could add additional tunneling commands to the config for a specific host. Do not add tunnels to all definitions as they may produce conflicts when you use the samen tunnel twice. So add the tunnel commands, for instance, to one host like:

Host hpc1tunnel
  HostName login1.alice.universiteitleiden.nl
  User <USERNAME>
  ProxyJump <USERNAME>@ssh-gw.leidenuniv.nl:22
  LocalForward 8081:management.alice.universiteitleiden.nl:8081
  LocalForward 8080:management.alice.universiteitleiden.nl:443

Alternatively, if your openssh server isn't that recent and doesn't recognize the ProxyJump alias, try this:

Host hpc1 
  HostName login1.alice.universiteitleiden.nl
  ForwardX11 yes
  User <USERNAME>
  ProxyCommand ssh -X <USERNAME>@sshgw.leidenuniv.nl -W %h:%p

Login to ssh-gw.leidenuniv.nl (ssh <USERNAME>@ssh-gw.leidenuniv.nl) and put your public key in

~/.ssh/authorized_keys

Login through to the HPC login1 node ''ssh login1.alice.universiteitleiden.nl' and put the same public key in

~/.ssh/authorized_keys

Direct login to login node 1

 ssh hpc1

and you can even forward X11 now.

File transfer to login node 1

 ssh <local_file_name> hpc1:<remote_file_name>

this copies the <local_file_name> file to <remove_file_name> file in your home directory on ALICE.

Tunneling to monitors

Having setup the ssh tunneling required to access the monitoring tools on the cluster you are now able to access port 443 (general secure web server on the management node) and port 8081 (specific port in use by the Bright Cluster Manager monitoring tools).

So in a browser you could type:

https://localhost:8080

to gain access to the management main web server, or you could type:

https://localhost:8081/userportal

to gain access to the Bright Cluster Manager User Portal.

Login to ALICE from Windows

In windows you can make use of the program putty. In order for putty to correctly handle tunnels we have to setup two login session. The first session opens a login to the ssh gateway and sets up a tunnel to allow login to the ALICE login node. Once this gateway login session is running you can define a second session to login to the ALICE login node and define tunnels for whatever purpose you need.

Setup putty configuration

Open the configuration and create a saved session with a name that you can remember: ALICE_GW. In the Host Name field enter the the gateway to which we first have to login: sshgw.leidenuniv.nl.

then go to the SSH tab en fill in the tunnels to the ALICE login 1 and login 2 nodes:

This definition now allows you to define two other session, one to login node 1and one to login node 2. Let's create the login 2 one:

Fill in as Host Name the tunnel information created in eth ALICE_GW definitions: localhost or 127.0.0.1 and use port 2221 for login node 1 and 2222 for login node 2. Now setup the tunnel definitions for anything you need:

In this case we setup a tunnel to the WEBserver of the management node. This will allow us to open a browser on your windows desktop with the URL: https://localhost:8080.
Save the configuration under a name that you can remember: ALICE_login1

Login and use tunnels

• Now open the first configuration ALICE_GW and login to the gateway.
• Second open the second configuration ALICE_login1
• Then you can perform your operations on login node 1 and also inspect the webpages from the management node web server directly from your desktop.