Multiple SSH Keys on GitHub

Recently I ran into an issue I’d never had before. I wanted to access more than one GitHub account from the same machine using SSH. I needed to figure out how to use multiple SSH keys on GitHub from one computer.

In this case it was due to my new job having our code hosted on GitHub and wanting to still access my personal account. This problem isn’t isolated to GitHub, of course. Pretty much any cloud-based system with SSH support could suffer this same issue.

Generating the SSH Pair

Presumably, you already know how to generate a key. Here’s GitHub’s documentation on generating ssh key pairs. In this case, however, since you probably already have one called id_rsa, just make sure you give the new one a different filename. For my example let’s pretend I’m creating one for work and calling it id_rsa_work.

Once you’ve generated the new pair you can associate it to the GitHub account you don’t already have a key associated with. See GitHub’s documentation on doing that in case you’ve forgotten.

Now before I go any farther on my post, I want to call out kudos to Oanh Nguyen and his gist. It’s what got me 99% of the way there.

Edit (or create) ssh config

Navigate to your ~/.ssh folder. In Windows, this is found within c:\Users\[username]\.ssh. From bash you can simply access it via cd ~/.ssh. If you don’t have a config file, you can issue the touch config command (or Windows command prompt, simply copy NUL config).

Within this config file you’ll need a couple host mappings. One for each account. Something like the following:

# Default github account: personal
Host github.com
   HostName github.com
   IdentityFile ~/.ssh/id_rsa
   IdentitiesOnly yes
   
# Other github account: work
Host github-work
   HostName github.com
   IdentityFile ~/.ssh/id_rsa_work
   IdentitiesOnly yes

Depending on the computer, you may want “work” to be your default instead of personal. Totally personal preference here.

Now I have multiple SSH keys I can use on GitHub!

Add ssh private keys to agent

In the examples I found, I actually was able to skip this step. I’m uncertain if it is because it automatically added it to my ssh-agent or what. All I know is that I could skip it. I’m including it for good measure anyway.

$ ssh-add ~/.ssh/id_rsa
$ ssh-add ~/.ssh/id_rsa_work

After adding them (or, in my case, I didn’t have to), be sure to test them out. You can issue the following commands to test the connection:

$ ssh -T git@github.com
$ ssh -T git@github-work

Cloning the repo

For your default account, clone as normal. For the other account, however, you’ll need to slightly modify the url.

$ git clone git@github-work:org2/project2.git

You may also want to update the user.name and user.email on the cloned repo:

$ cd /path/to/project2
$ git config user.email "myworkemail@org2.com"
$ git config user.name  "My Name"

Conclusion

It is possible to have multiple SSH keys on your computer in order to access different GitHub accounts. Making use of the .ssh/config file and creative usage of the host property allows you to access those accounts.

Other Resources

My initial Googling for help turned up a few links. Between two of them in particular and the comments, I was able to get up and running.

oanhnn has a gist for using multiple github accounts with ssh keys.
jexchan also has a gist but I found oanhnn’s more up-to-date.
See also Bitbucket on setting up additional SSH keys.

Credits

Photo by Skitterphoto from Pexels