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
User USERNAME
Host moto
Hostname moto.rcs.columbia.edu
User USERNAME
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.