Authenticate with SSH

SSH authentication lets a Git host identify your computer through a key pair.

The pair contains a private key and a public key. The private key stays on your computer. You add the public key to the account on the Git host.

Create a modern key with a label that identifies it:

ssh-keygen -t ed25519 -C "[email protected]"

Follow the prompts and protect the private key with a passphrase. Your operating system or SSH agent can remember the unlocked key for a session.

Files ending in .pub contain the public key. Inspect the names carefully before copying anything:

ls -la ~/.ssh

Add the public key content to GitHub, then test the SSH connection using GitHub’s documented test command. A successful authentication does not grant access to every repository; repository permissions still apply.

Use an SSH remote URL:

git remote set-url origin [email protected]:flaviocopes/myrepo.git
git remote -v

The file ending in .pub is safe to copy to a service. Never share the private key.

If a key is exposed, remove its public counterpart from services and replace the pair. Do not commit keys to a repository.

Exercise: identify the public and private files in a disposable key pair without printing the private key content.