GitHub using the wrong SSH key

I have two GitHub accounts setup with ssh keys, one personal and one enterprise.

I have an ssh config file as such:

# * GitHub CKO SSH Key
Host github-enterprise
  HostName github.com
  AddKeysToAgent yes
  UseKeychain yes
  User git
  IdentityFile ~/.ssh/id_ed25519_github

# * GitHub Personal SSH Key
Host github-personal
  HostName github.com
  AddKeysToAgent yes
  UseKeychain yes
  User git
  IdentityFile ~/.ssh/gh_mervinhemaraju_ed25519

Both keys were created seperately and attached to the respective account.

The weird issue is that I was using this for like a month, and it was working. Today, when i logged in, i committed some work on my personal repo and when i tried to do a remote push (which was working for this repo previously), i got and user permission denied.

I then performed an ssh test on both ssh keys and the results was as such:

ssh -T ssh -T git@github-personal

Hi mervin-hemaraju-enterprise! You've successfully authenticated, but GitHub does not provide shell access.

ssh -T git@github-enterprise

Hi mervin-hemaraju-cko! You've successfully authenticated, but GitHub does not provide shell access.

The personal key test is wrong. It should've been Hi mervinhemaraju! You've successfully authenticated, but GitHub does not provide shell access. since mervinhemaraju is my personal account, but is instead referring to the enterprise one.

I am on MacOs. Can someone please help ?

Solution

Add IdentitiesOnly yes for the entries in the ssh config. This will prevent the SSH Agent from trying all the keys it knows of and only use the ones specified in the config file.

Specifies that ssh should only use the identity keys configured in the ssh_config files, even if ssh-agent offers more identities. https://www.ssh.com/academy/ssh/config