I recently had to setup multiple SSH profiles for Github. The reason why I had this requirement as my work required me to have a Github account outside of my personal account. The machine I am using is used for both work and personal development. I needed both SSH keys to work. I had never ran into this before as I never had two Github accounts. Since you are not able to use the same ssh key between multiple accounts in Github I had to come up with a way for both to work together. This makes sense for security purposes that the key should only be identified with one account. The process to set this up was pretty simple overall but that is after you understand what you need to do. Understanding exactly what is needed can be tricky at least from the documentation I found online.
The first thing you need to do is create a SSH key pair for both your personal account and work account. They should be using different email addresses.
$ ssh-keygen -t rsa -C "firstname.lastname@example.org" # follow prompts use defaults if you want $ ssh-keygen -t rsa -C "email@example.com" # specify new name for key
After that is done you should have a couple of keys. For example you could have id_rsa and id_rsa_work or whatever you called them. Add the proper SSH keys to your Github accounts following Generating SSH Keys – Github. The documentation there is really well done so no further explanation is needed.
So now you should be able to use each SSH account by adding it. Everything will work at this point but you will have to keep adding the ssh-add when you switch between accounts. If you don’t switch often this may be fine but it’s a really pain if you switch often. Also you tend to forget overtime why it’s broken all the sudden.
The next step is you need to create an SSH config to handle the multiple accounts.
sudo vim ~/.ssh/config # add in the hosts # Inside the file add the following Host github.com-personal HostName github.com User git IdentityFile ~/.ssh/id_rsa Host github.com-work HostName: github.com User git IdentityFile ~/.ssh/id_rsa_work
Save and close it out and that part should be all set. The next part is the most critical. If you have an existing repo go and modify your SSH string to add in the -work or -personal. This is whatever you named your host. Here is an example for my personal project.
If you are adding a new clone or new remote continue to use the same host name you set in your SSH profile. After you run the process it all makes sense it looks at the ssh config to determine which key to use.