Multiple GitHub Accounts & SSH Config

Question

I'm having some trouble getting two different SSH keys/GitHub accounts to play well together. I have the following setup:

Repos accessible from one account using [e-mail]:accountname

Repos accessible from another account using [e-mail]:anotheraccount

Each account has its own SSH key. Both SSH keys have been added and I have created a config file. I don't believe the config file is correct though. I'm not quite sure how to specify that repos accessed using [e-mail]:accountname should use id_rsa and [e-mail]:anotheraccount should use id_rsa_anotheraccount.

Answer 1

I have 2 accounts on github, and here is what I did (on linux) to make it work.

Keys

• Create 2 pair of rsa keys, via ssh-keygen, name them properly, so that make life easier.
• Add private keys to local agent via ssh-add path_to_private_key
• For each github account, upload a (distinct) public key.

---

Configuration

~/.ssh/config

Host github-kc
    Hostname        github.com
    User git
    IdentityFile    ~/.ssh/github_rsa_kc.pub
    # LogLevel DEBUG3

Host github-abc
    Hostname        github.com
    User git
    IdentityFile    ~/.ssh/github_rsa_abc.pub
    # LogLevel DEBUG3

Set remote url for repo:

• For repo in Host github-kc:

  git remote set-url origin git@github-kc:kuchaguangjie/pygtrans.git
  

• For repo in Host github-abc:

  git remote set-url origin git@github-abc:abcdefg/yyy.git
  

---

Explaination

Options in ~/.ssh/config:

• Host github-<identify_specific_user>
  Host could be any value that could identify a host plus an account, it don't need to be a real host, e.g github-kc identify one of my account on github for my local laptop,
  

  When set remote url for a git repo, this is the value to put after git@, that's how a repo maps to a Host, e.g git remote set-url origin git@github-kc:kuchaguangjie/pygtrans.git

• 
  
• [Following are sub options of Host]
• Hostname
  specify the actual hostname, just use github.com for github,
• User git
  the user is always git for github,
• IdentityFile
  specify key to use, just put the path the a public key,
• LogLevel
  specify log level to debug, if any issue, DEBUG3 gives the most detailed info.

---

Answer 2

A possibly simpler alternative to editing the ssh config file (as suggested in all other answers), is to configure an individual repository to use a different (e.g. non-default) ssh key.

Inside the repository for which you want to use a different key, run:

git config core.sshCommand 'ssh -i ~/.ssh/id_rsa_anotheraccount'

And make sure, your key is added to the ssh-agent, by running:

ssh-add ~/.ssh/id_rsa_anotheraccount

Keep in mind that the command above will only add key to the ssh-agent for your current session. If you want this to work forever, you have to "permanently" add it to your ssh-agent. E.g here's how to do it for ubuntu and here for OSX.

^{It should also be possible to scale this approach to multiple repositories using global git config and conditional includes (see example).}

Answer 3

I recently had to do this and had to sift through all these answers and their comments to eventually piece the information together, so I'll put it all here, in one post, for your convenience:

Step 1: ssh keys
Create any keypairs you'll need. In this example I've named me default/original 'id_rsa' (which is the default) and my new one 'id_rsa-work':

ssh-keygen -t rsa -C "[e-mail]"

Step 2: ssh config
Set up multiple ssh profiles by creating/modifying ~/.ssh/config. Note the slightly differing 'Host' values:

# Default GitHub
Host github.com
    HostName github.com
    PreferredAuthentications publickey
    IdentityFile ~/.ssh/id_rsa

# Work GitHub
Host work.github.com
    HostName github.com
    PreferredAuthentications publickey
    IdentityFile ~/.ssh/id_rsa_work

Step 3: ssh-add
You may or may not have to do this. To check, list identity fingerprints by running:

$ ssh-add -l
2048 1f:1a:b8:69:cd:e3:ee:68:e1:c4:da:d8:96:7c:d0:6f stefano (RSA)
2048 6d:65:b9:3b:ff:9c:5a:54:1c:2f:6a:f7:44:03:84:3f [e-mail] (RSA)

If your entries aren't there then run:

ssh-add ~/.ssh/id_rsa_work

Step 4: test
To test you've done this all correctly, I suggest the following quick check:

$ ssh -T [e-mail]
Hi stefano! You've successfully authenticated, but GitHub does not provide shell access.

$ ssh -T [e-mail]
Hi stefano! You've successfully authenticated, but GitHub does not provide shell access.

Note that you'll have to change the hostname (github / work.github) depending on what key/identity you'd like to use. But now you should be good to go! :)

Answer 4

I posted the technique I use to deal with these here

Answer 5

I spent a lot of time to understand all the steps. So lets describe step by step:

1. Create new identity file using ssh-keygen -t rsa. Give it an alternative like proj1.id_rsa and hit with no doubt because you don't need a passphrase.

2. Add new section in .ssh/config:

   Host proj1.github.com
       HostName github.com
       PreferredAuthentications publickey
       IdentityFile ~/.ssh/proj1.id_rsa
   

Take into account the first section and note that proj1.github.com we will back to the section later.

3. Add the identity to ssh agent ssh-add ~/.ssh/proj1.id_rsa
4. That what I messed first time - now when you want to clone a proj1 repo you do it using proj1.github.com (exactly the host from the config file). git clone [e-mail].

A good tutorial.

Don't mess up with hosts