Login to HPC passwordless

Login to HPC passwordless

Set up a shortcut to login by SSH

In a linux or OSX terminal you will have a hidden directory in HOME called ~.ssh which contains files for setting preferences or login credentials to make it simpler and faster to login to remote systems. Let’s start by setting a shortcut for the two clusters at Columbia in a file called ~.ssh/config. The code below shows the typical longform SSH login command and the shorter version that we will be able to use once you setup your config file.

# what you do now
ssh username@habanero.rcs.columbia.edu

# what you want to be able to do
ssh habanero

To setup the config file use a text editor like nano to create and edit the config file by calling nano ~/.ssh/config and then enter the following being sure to replace USERNAME with your actual username.

Host habanero
    Hostname habanero.rcs.columbia.edu

Host moto
    Hostname moto.rcs.columbia.edu

Setup passwordless login

Great, now that we can call the command to login to the cluster more easily let’s also make it so that you do not need to enter a password. We can do this by sharing SSH credentials between your laptop and the cluster. This is a two-step process.

1. Generate an SSH key

Enter your email address here of course. This will prompt you to enter a password for which you should enter the password you wish to use to login to the cluster (you can set this to not ask later).

ssh-keygen -t rsa -b 4096 -C "user@email.org"

2. Send SSH key to the HPC

Now we send the key to the cluster.

ssh-copy-id -i ~/.ssh/id_rsa.pub habanero

And repeat for the other cluster.

ssh-copy-id -i ~/.ssh/id_rsa.pub moto

That’s it. You should now be able to login more efficiently.