Managing multiple SSH Keys with Github & Gitlab

I have always stumbled on this problem of managing SSH keys for multiple Git based SCM (Gitlab, GitHub) including multiple GitHub accounts.

If you’ve single account - adding the SSH keys on your github or gitlab is simple.

I currently have the following accounts:

Github

1 personal account
2 behind the firewall (corporate accounts)

Gitlab

1 personal account
1 corporate account

If ever face a problem like this, it is best to create a ssh-config file which aggregates all your SSH keys. You must follow the steps below:

1. Generate SSH keys for each account and give a name accordingly

Follow the command below to generate SSH keys for each account on GitHub or Gitlab

cd ~/.ssh
ssh-keygen -t rsa -C "your-email@abc.com" -f ~/.ssh/id_rsa_account-1-github
ssh-keygen -t rsa -C "your-email@abc.com" -f ~/.ssh/id_rsa_account-2-github

ssh-keygen -t rsa -C "your-email@abc.com" -f ~/.ssh/id_rsa_account-1-gitlab
ssh-keygen -t rsa -C "your-email@abc.com" -f ~/.ssh/id_rsa_account-2-gitlab

This should produce multiple pairs of private and public keys:

- id_rsa_account-1-github
- id_rsa_account-1-github.pub

- id_rsa_account-2-github
- id_rsa_account-2-github.pub
.....

2. Add the public key to the respective account on GitHub or Gitlab

Copy the text under each public key and paste them content for each account on GitHub & Gitlab (this should be easy)

3. Create and map the keys in a Config file

Next create a config file under ~/.ssh directory with the following content:

Host github.com
  User git
  Port 22
  Hostname github.com
  IdentityFile ~/.ssh/id_rsa_account-1-github
  TCPKeepAlive yes
  IdentitiesOnly yes
  Hostname github.com
  IdentityFile ~/.ssh/id_rsa_account-2-github

Host gitlab.com
  User git
  Port 22
  Hostname gitlab.com
  IdentityFile ~/.ssh/id_rsa_account-1-gitlab
  TCPKeepAlive yes
  IdentitiesOnly yes
  Hostname gitlab.com
  IdentityFile ~/.ssh/id_rsa_account-2-gitlab

Let’s validate the settings through a quick CLI:

ssh -vT git@github.com

You should get a verbose output with successful autheticated message:

Hi <user account>! You've successfully authenticated, but GitHub does not provide shell access.

Hope it helps!