How to set up authentication for two separate GitHub accounts from same ssh client?

Question

The short version:

Is there any way to set up automatic public-key-based ssh authentication from one Linux account to two different Github accounts?

Answer 1

You need to create two sets of (public/private) keys, one for each account.

You can reference them through an ssh config file, as detailed in "GitHub: Multiple account setup"/

#Account one
Host github.com
    HostName github.com
    PreferredAuthentications publickey
    IdentityFile /c/Users/yourname/.ssh/id_rsa
    User git

#Account two
Host ac2.github.com
    HostName github.com
    PreferredAuthentications publickey
    IdentityFile /c/Users/yourname/.ssh/id_rsa_ac2
    User git

Answer 2

It seems GitHub doesn't allow the same RSA key for two repositories.

As workaround, you've to create separate RSA keys for each site:

ssh-keygen -t rsa -f rsa_site1
ssh-keygen -t rsa -f rsa_site2

This will generate private and public keys. Then add public keys into GitHub to Deploy keys.

Then deploy your private keys into the remote:

cat rsa_site1 | ssh user@remote "cat > ~/.ssh/rsa_site1 && chmod 600 ~/.ssh/rsa_site1"
cat rsa_site2 | ssh user@remote "cat > ~/.ssh/rsa_site2 && chmod 600 ~/.ssh/rsa_site2"

And to fetch your private repository on the server, you can use something like:

ssh user@remote 'ssh-agent sh -c '\''cd /webroot/site1 && ssh-add ~/.ssh/rsa_site1 && git fetch git@github.com:priv/site1.git'\'
ssh user@remote 'ssh-agent sh -c '\''cd /webroot/site2 && ssh-add ~/.ssh/rsa_site2 && git fetch git@github.com:priv/site2.git'\'