SSH Setup for GitHub

2020-12-11

4 minute read
#ssh  #tutorial 

Setting up SSH keys

References:

  1. How to Get and Configure Your Git and GitHub SSH Keys
  2. The Ultimate Guide to SSH - Setting Up SSH Keys

If you follow those references above, you will be proabably all set. But I am just going to leave the summary on how to go about setting up multiple SSH keys so that if you have multiple GitHub accounts or some other accounts with GitLab or BitBucket, this post might give you an idea.

1. Check for existing keys

  • Run ls -al ~/.ssh to see if you have any existing SSH keys.

If you see something like the following output, you should already have an SSH key.

-rw-------  1 user_name user_name  1766 Jul  7  2018 id_rsa
-rw-r--r--  1 user_name user_name   414 Jul  7  2018 id_rsa.pub
-rw-------  1 user_name user_name 12892 Feb  5 18:39 known_hosts

If you don't see any output, you probably don't have any SSH keys.

So run mkdir $HOME/.ssh to create a .ssh directory.

Then generate a new set of keys:

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

Now run ls -la ~/.ssh again to see if the set of keys has been generated successfully. 😎

2. ssh-agent

Run the following command to see if the agent is running:

eval "$(ssh-agent -s)" # for Mac and Linux

or

eval `ssh-agent -s`
ssh-agent -s # for Windows

Then add your private key to ssh-agent:

ssh-add ~/.ssh/id_rsa

After that,

  1. Copy your public key(id_rsa.pub).
  2. Sign in to your GitHub account.
  3. From your account dropdown, go to Settings -> SSH and GPG keys.
  4. Click on "New SSH key" button.
  5. Paste the copied public key into the textarea of "Key".

Lstly, check your authentication:

ssh -T git@github.com

If you see the following message, your SSH key has been successfully set up! 🖖

Hi your_user_name! You've successfully authenticated, but GitHub does not provide shell access.




So now, how about adding another account?



Carefully run:

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

But, this time, you will have to change the file name manually.

When you run the command above, you should see the following messages:

Generating public/private rsa key pair.
Enter file in which to save the key (/home/username/.ssh/id_rsa):

When you generated a set of keys for the first time, you didn't really need to specify the file name even though you could have if you wanted to.

But as you generate more keys, you must specify the file name.

For example, if you are generating a key for your work, then you might want to enter something like:

/home/<your_username>/.ssh/id_rsa_work

Now, when you run ls -la ~/.ssh, you should see the following output or something similar:

-rw-------  1 user_name user_name  1766 Jul  7  2018 id_rsa
-rw-r--r--  1 user_name user_name   414 Jul  7  2018 id_rsa.pub
-rw-------  1 user_name user_name  1766 Jul  7  2018 id_rsa_work
-rw-r--r--  1 user_name user_name   414 Jul  7  2018 id_rsa_work.pub
-rw-------  1 user_name user_name 12892 Feb  5 18:39 known_hosts

Lastly, ssh-add ~/.ssh/id_rsa_work and when you ssh-add -l, you should see all your identities in the output.

3. Create ~/.ssh/config

When you have multiple SSH keys, creating config file under your .ssh directory is a must.

So let's do that.

Run touch ~/.ssh/config to create config file, and then open it with your favorite text editor.

Copy and paste the following as a template:

# personal
Host github.com # Change `github.com` to the name of your like.
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_rsa_personal # Change it to the correct path.

# work
Host github.com-work # Change `github.com-work` to the name of your like.
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_rsa_work # Change it to the correct path.

In this example, we have configured multiple accounts for GitHub.

4. How do you switch between identities?

Every terminal session, you will have to ssh-add ~/.ssh/<identity_file> to add the identity you want to use.

If an identity is somehow already set and you want to switch to a different one, then you will have to ssh-add -D to drop that identity and ssh-add ~/.ssh/<identity_file> to add the identity you want to use.

You cannot use multiple identities during the same session.

And I think that's about it.

One thing to keep in mind is that, if you have globally set github username and email, you might want to configure your .git whenever you initialize a git repo:

git config user.name "Your name"
git config user.email your_email@example.com
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