Multiple SSH keys for different Git accounts

🗒️ Content

1. Before SSH Keys Setup
2. Connecting to GitLab with SSH
3. Connecting to GitHub with SSH
4. A Better Keys Organization

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1. Before SSH Keys Setup

• Checking for existing SSH keys file

$ ls ~/.ssh
id_rsa  id_rsa.pub  known_hosts

• Confirm active public SSH keys (*.pub) in ssh-agent

$ ssh-add -L

• Remove all old keys

$ rm -r ~/.ssh

2. Connecting to GitLab with SSH

• Step 1: Generate an SSH key pair

$ ssh-keygen -t ed25519 -C "<your_email_01>@gmail.com"
Generating public/private ed25519 key pair.
Enter file in which to save the key (/home/<user>/.ssh/id_ed25519): /home/<user>/.ssh/id_ed25519_gitlab
Enter passphrase (empty for no passphrase):
Enter same passphrase again:

• Step 2: Add an SSH key to your GitLab account

$ cat ~/.ssh/id_ed25519_gitlab.pub
# or
$ xclip -sel clip < ~/.ssh/id_ed25519_gitlab.pub

Copy the contents of your public key file by manually or a script. Then coming to GitLab > Preferences > SSH Keys

• Step 3: Verify that you can connect

$ ssh -T [e-mail]
...
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Welcome to GitLab, <user_name>!

3. Connecting to GitHub with SSH

• Step 1: Generate an SSH key pair

$ ssh-keygen -t ed25519 -C "<your_email_02>@gmail.com"
Generating public/private ed25519 key pair.
Enter file in which to save the key (/home/<user>/.ssh/id_ed25519): /home/<user>/.ssh/id_ed25519_github
Enter passphrase (empty for no passphrase):
Enter same passphrase again:

• Step 2: Add an SSH key to your GitLab account

$ cat ~/.ssh/id_ed25519_github.pub
# or
$ xclip -sel clip < ~/.ssh/id_ed25519_github.pub

Copy the contents of your public key file by manually or a script. Then coming to GitHub > Settings > SSH and GPG keys

• Step 3: Verify that you can connect

$ ssh -T [e-mail]
...
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Hi <user_name>! You've successfully authenticated, but GitHub does not provide shell access.

4. A Better Keys Organization

For more information on these settings, see the man ssh_config

$ cd ~/.ssh/
$ touch config
$ vi config
# GitLab
Host gitlab.com
  PreferredAuthentications publickey
  IdentityFile ~/.ssh/id_ed25519_gitlab

# GitHub
Host github.com
  PreferredAuthentications publickey
  IdentityFile ~/.ssh/id_ed25519_github