This guide walks you through configuring SSH authentication with Git CLI for secure repository access.

• Git installed on your system
• Access to a terminal/command line
• A Git hosting account (GitHub, GitLab, or Bitbucket)

First, check if you already have SSH keys:

ls -al ~/.ssh

Look for files like id_rsa.pub, id_ed25519.pub, or id_ecdsa.pub.

If you don't have an SSH key, generate one using Ed25519 (recommended):

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

For legacy systems that don't support Ed25519, use RSA:

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

During key generation:

• Press Enter to accept the default file location (~/.ssh/id_ed25519)
• Optionally set a passphrase for additional security
• Press Enter again to confirm the passphrase

Start the SSH agent in the background:

eval "$(ssh-agent -s)"

You should see output like: Agent pid 12345

Add your SSH private key to the SSH agent:

ssh-add ~/.ssh/id_ed25519

Note: If you generated an RSA key, use ~/.ssh/id_rsa instead.

Display your public key:

cat ~/.ssh/id_ed25519.pub

Copy the entire output (it should start with ssh-ed25519 or ssh-rsa).

Alternative method (copies directly to clipboard):

• macOS: pbcopy < ~/.ssh/id_ed25519.pub
• Linux (with xclip): xclip -selection clipboard < ~/.ssh/id_ed25519.pub
• Windows (Git Bash): clip < ~/.ssh/id_ed25519.pub

1. Go to GitHub Settings
2. Click SSH and GPG keys → New SSH key
3. Add a descriptive title (e.g., "Work Laptop")
4. Paste your public key in the "Key" field
5. Click Add SSH key

1. Go to GitLab Preferences
2. Click SSH Keys
3. Paste your public key in the "Key" field
4. Add a title and optional expiration date
5. Click Add key

1. Go to Bitbucket Personal Settings
2. Click SSH keys → Add key
3. Add a label
4. Paste your public key
5. Click Add key

Verify that your SSH key is working:

GitHub:

ssh -T git@github.com

GitLab:

ssh -T git@gitlab.com

Bitbucket:

ssh -T git@bitbucket.org

You should see a success message like: Hi username! You've successfully authenticated...

git clone git@github.com:username/repository.git

Check your current remote URL:

git remote -v

Change to SSH:

git remote set-url origin git@github.com:username/repository.git

Verify the change:

git remote -v

If you get a "Permission denied" error:

1. Verify your SSH key is added to the agent: ssh-add -l
2. Check that you've added the correct public key to your Git provider
3. Ensure you're using the correct SSH URL format
4. Try adding your key again: ssh-add ~/.ssh/id_ed25519

If the SSH agent isn't running, start it:

eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519

If you have multiple SSH keys, specify which one to use:

ssh-add -D  # Remove all keys
ssh-add ~/.ssh/id_ed25519  # Add specific key

Create or edit ~/.ssh/config to manage multiple keys or customize settings:

Host github.com
    HostName github.com
    User git
    IdentityFile ~/.ssh/id_ed25519
    
Host gitlab.com
    HostName gitlab.com
    User git
    IdentityFile ~/.ssh/id_ed25519_gitlab

• Use a strong passphrase for your SSH key
• Never share your private key (id_ed25519 or id_rsa)
• Only share your public key (.pub files)
• Regularly rotate your SSH keys
• Use different keys for different services if needed
• Remove old or unused SSH keys from your Git provider

• GitHub SSH Documentation
• GitLab SSH Documentation
• Bitbucket SSH Documentation

License: MIT
Last Updated: November 2025