Managing Multiple Git Server Keys

When you work with multiple git servers or need different credentials for different hosts, SSH’s config file lets you specify which key to use for each server. This is cleaner than managing aliases or environment variables.

Setting Up ~/.ssh/config

Create or edit ~/.ssh/config and add entries for each server:

Host git.example.org
  Port 22111
  IdentityFile ~/.ssh/id_rsa.git.example.org
  User git

Host code.example.org
  Port 22
  IdentityFile ~/.ssh/id_rsa.code.example.org
  User git

Host github.com
  HostName github.com
  IdentityFile ~/.ssh/id_rsa.github
  User git

Each Host block specifies:

• Port: SSH port if non-standard (default is 22)
• IdentityFile: Path to the private key for this server
• User: SSH username (usually git for git servers)
• HostName: The actual hostname if different from the Host alias

Set proper permissions:

chmod 600 ~/.ssh/config
chmod 600 ~/.ssh/id_rsa.*

Using the Configuration

Once configured, git automatically uses the right key based on the remote URL. Clone normally:

git clone git@git.example.org:team/project.git
git clone git@code.example.org:org/repo.git
git clone git@github.com:user/repo.git

Git matches the hostname in your URL to the Host entry and applies the corresponding configuration.

Common Patterns

Multiple accounts on the same server — use host aliases:

Host github-work
  HostName github.com
  IdentityFile ~/.ssh/id_rsa.work
  User git

Host github-personal
  HostName github.com
  IdentityFile ~/.ssh/id_rsa.personal
  User git

Then clone work repos with git@github-work:company/repo.git and personal repos with git@github-personal:username/repo.git.

Self-hosted servers with custom ports:

Host gitlab.internal
  HostName gitlab.company.local
  Port 2222
  IdentityFile ~/.ssh/id_rsa.internal
  User git

Debugging SSH Issues

Verify which key is being used for a specific host:

ssh -v git@github.com

Look for lines like Offering public key or Trying private key to confirm the correct identity file is being attempted.

Test the configuration without cloning:

ssh -T git@github.com

This connects and authenticates without performing git operations — useful for verifying setup.

Ed25519 Keys (Modern Alternative)

Consider using Ed25519 keys instead of RSA for better security and smaller key size:

ssh-keygen -t ed25519 -C "git@example.org" -f ~/.ssh/id_ed25519.example

Then reference in config:

Host git.example.org
  IdentityFile ~/.ssh/id_ed25519.example

Key Points

• SSH checks ~/.ssh/config before attempting authentication, so the right key is always selected automatically
• The Host value in the config file must match the hostname in your git remote URL exactly (unless you use HostName to redirect)
• If a server rejects your key, verify the public key is added to that server’s authorized_keys and that file permissions are correct (700 for the directory, 600 for the file)
• You can test multiple identities with IdentityFile entries — SSH tries them in order until one works

Git Workflow Tips

Effective Git usage goes beyond knowing individual commands. Consider adopting a branching strategy that suits your team size. Feature branching works well for small teams, while GitFlow or trunk-based development scales better for larger organizations.

Always write descriptive commit messages. A good commit message explains what changed and why, not just what. Use the imperative mood: “Add feature” not “Added feature”.

Useful Git Shortcuts

Add these aliases to your Git configuration for faster daily workflows:

[alias]
    st = status -sb
    co = checkout
    br = branch -v
    lg = log --oneline --graph --decorate -20
    unstage = reset HEAD --
    amend = commit --amend --no-edit
    last = log -1 HEAD --stat

Quick Verification

After applying the changes described above, verify that everything works as expected. Run the relevant commands to confirm the new configuration is active. Check system logs for any errors or warnings that might indicate problems. If something does not work as expected, review the steps carefully and consult the official documentation for your specific version.