SSH login to GitHub and GitLab

Generate a pair of SSH keys¶

ssh-keygen -t ed25519 -C "your_email@example.com"

The SSH agent will ask you to enter a location to save the keys. e.g. /home/user/.ssh/id_ed25519. Passphrase is optional.
Then there will be two SSH key files:

~/.ssh/id_ed25519 is the private key. Protect it at all costs.
~/.ssh/id_ed25519.pub is the public key.

Using different keys for GitHub and GitLab access is more secure. However, the same pair of keys is used for this demonstration purposes.

Add remote to the SSH settings¶

Edit ~/.ssh/config

mkdir -p ~/.ssh
touch ~/.ssh/config
chmod 600 ~/.ssh/config
nano ~/.ssh/config

Add the following content to set the private key as the IdentityFile.

~/.ssh/config

Host GitHub
  HostName github.com
  IdentityFile ~/.ssh/id_ed25519

Host GitLab
  HostName gitlab.com
  IdentityFile ~/.ssh/id_ed25519

Add the SSH key to your GitHub account¶

According to 📖 Github docs, add the SSH key here

Paste the content of the public key, ~/.ssh/id_ed25519.pub to the key field.
Add a descriptive label for the new key in the "Title" field.
Finally, click the Add SSH key green button. If prompted, confirm your GitHub password.

Add the SSH key to your GitLab account¶

Add the SSH key here

Paste the content of the public key, ~/.ssh/id_ed25519.pub to the key field.
Add a descriptive label for the new key in the "Title" field.
Select an expiration date.
Finally, click the Add key button.

Test your setup¶

GitHub:

ssh -vT git@github.com

Accept its fingerprint if prompted. If you see "Hi user! You've successfully authenticated, but GitHub does not provide shell access" that means login is successful.

GitLab:

ssh -vT git@gitlab.com

Accept its fingerprint if prompted.