Creating SSH Key-pair

How to enable SSH authentication between Colab and GitHub for private repositories.

This document will lay out the steps you need to take to create an SSH key-pair, followed by the steps necessary to establish the SSH authentication between Colab and GitHub for private repositories.

A note to the reader

I started putting together this document with the intent to enable SSH based authentication between Colab and GitHub for private repositories. The steps involved are:

  1. Check for existing SSH keys. DONE
  2. Create SSH public-private key-pair. DONE
  3. Create a .config file in directory with only the key-pair files in it and gzip it. TESTED => But have not written down the exact process here. PENDING
  4. Upload the gzipped file to Colab. TESTED
  5. Run script to set colab environment with the public-private key-pair. PENDING
  6. Save the public-key in GitHub. PENDING
  7. Test if it worked. PENDING

Note:

  • I mostly followed this document to implement these steps. There is also a similar article available on Medium.com by the same author.

  • At this point I am not sure if this is a once-only activity or you need to run it everytime you fire up a new Colab VM. I plan on testing and documenting it. My ultimate goal with this document is to make Colab-GitHub SSH integeration as simple as possible. Worst-case-scenario: I would run a colab-script every time I open up a Colab VM and access my SSH key-pair from a predefined location on my Google Drive (and avoid uploading the SSH key-pair every time).

Check for existing SSH keys

Use this command to list all existing SSH keys: ls -al ~/.ssh Follow this article for more details: https://help.github.com/en/articles/checking-for-existing-ssh-keys

Create SSH public-private key-pair

  • Step-1
    You can create an rsa key-pair with the following single line command. Run it in PuTTy, Git Bash, CygWin, etc.
ssh-keygen -f ~/.ssh/id_rsa_<file-name> -t rsa -b 4096 -C "your.email.id@your_email.com"
  • Step-2
    You will be prompted for a passphrase. Just press enter to proceed without a passphrase.

For example, if your email is john.doe@gmail.com and you want to create SSH key-pairs using rsa algorithm with key-size of 4096, and you would like to name your SSH key-pairs id_rsa_colab, you could do that by running the following command from Git Bash and when prompted for a passphrase, just press enter to proceed without a passphrase.

ssh-keygen -f ~/.ssh/id_rsa_colab -t rsa -b 4096 -C "john.doe@gmail.com"

The letters -f, -t, -b, -C are called switches and are used to let the user specify details about key-pair filename, ssh algorithm, key-size, user email respectively.

Switch Use Example
-f Specify filename to store generated key-pair.
Usually, the keys are named as follows: <li> private-key: id_rsa_colab </li> <li> public-key: id_rsa_colab.pub </li>		 -f ~/.ssh/id_rsa_colab
-t Specify the type of algorithm to use. See all available types here. -t rsa
-b Specify the key-size of the algorithm. For instance, here we are
using rsa algorithm with a key-size of 4096.
The larger the key size the better.		 -b 4096
-C Specify user email -C john.doe@gmail.com

Additional Resources

  • To know more about the types of algorithms and available options for key-size while creating an SSH key-pair, refer to this document.
  • You may download Git Bash from here: https://gitforwindows.org/

References:

  1. Resource: https://techsupportallbugs.wordpress.com/2018/06/05/using-git-with-colab-via-ssh/
  2. Resource: https://www.digitalocean.com/community/tutorials/how-to-set-up-ssh-keys–2
  3. Resource: https://stackoverflow.com/questions/2505096/cloning-a-private-github-repo
  4. Resource: https://help.github.com/en/articles/adding-a-new-ssh-key-to-your-github-account
  5. Resource: https://help.github.com/en/articles/checking-for-existing-ssh-keys
  6. Resource: https://towardsdatascience.com/using-git-with-colab-via-ssh-175e8f3751ec
  7. Resource: https://www.ssh.com/ssh/keygen/
Written on December 2, 2020