SSH using old possibly cached user for connecting to GitHub

Question

Mac OS (High Sierra) here. I have an SSH key, example-gh-user, and when I run pbcopy < ~/.ssh/example-gh-user.pub and paste it into an editor I see:

ssh-ed25519 <SOME_REALLY_LONG_ALPHANUM> [email protected]

Obviously for security reasons I am replacing the actual value of <SOME_REALLY_LONG_ALPHANUM> and [email protected] with the dummy values above. But everything looks ok.

On GitHub, I have a user, example-gh-user, that is using the [email protected] email, and I can log in with that user and see all my repos. Everything appears fine.

I have followed the GitHub guide on adding an SSH key to my example-gh-user GitHub account. Hence, this SSH key should be associated with the same email address that my GH account is associated with.

In my ~/.ssh/config file, I have the following entries:

Host example-dev
  Hostname   github2.com
  AddKeysToAgent yes
  IdentityFile ~/.ssh/example-gh-user

Host github.com
  User git
  Hostname   github.com
  AddKeysToAgent yes
  PreferredAuthentications publickey
  IdentityFile ~/.ssh/example-gh-user

So far, so good, I think.

However, when I run the following from the command line:

ssh -Tv [email protected]

I get a huge dump of output that ends, interestingly-enough, with this:

debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
Hi my-old-gh-user! You've successfully authenticated, but GitHub does not provide shell access.
debug1: channel 0: free: client-session, nchannels 1
Transferred: sent 3452, received 2724 bytes, in 0.1 seconds
Bytes per second: sent 28403.1, received 22413.1
debug1: Exit status 1

Look at that! my-old-gh-user! That's an old GH user that I haven't used in years!

Where is SSH and/or git/GitHub looking to grab that my-old-gh-user from?! Does SSH cache old data some how? If I understand how everything works correctly, ~/.ssh/config clearly directs SSH to use ~/.ssh/example-gh-user when connecting as git user to github.com, right? Where am I going awry?

Answer 1

How can I tell what the current latest some-service/client version is, and how do I update go.mod to use it?

Simply go get github.com/SomeExampleOrg/some-service/client (assuming the original line is still in go.mod)

That will update go.mod to the latest for that repository, and the go.mod line about client will display the latest version available.

If that repository is a public one, Go will use the normal HTTPS URL, and your SSH configuration won't be needed.

---

TheOP mentions in the discussion

ssh -Tv [email protected]` generates the following output:

Hi my-old-gh-user! You've successfully authenticated, but GitHub does not provide shell access. 

my-old-gh-user is an old GH user that I haven't used in years and must have configured SSH for.

Where is SSH/GitHub grabbing the my-old-gh-user from?

By default, ssh will look for ~/.ssh/id_rsa(.pub). If that old public kay was registered to the old GitHub user account SSH profile setting (as documented by GitHub), that would explain why SSH identifies you by default with the old GitHub account.

Register a new public key in your new account, and make sure to replace the default one by your new key (or use an ~/.ssh/config file), and SSH will aithenticate you kwith the new account.

I generated ~/.ssh/example-gh-user

Then you need to add to your ~/.ssh/config file:

Host newgh
    HostName github.com
    User git
    IdentityFile ~/.ssh/example-gh-user

Then

ssh -Tv newgh

cd /path/to/repo
git remote set-url origin newgh:<me>/<repo>

Answer 2

The answer to this interesting scenario would lie on the way ssh-agent works and caches the identities(SSH keys) on MacOS' Keychains.

You can do ssh-add -L to get all the currently loaded identities, wherein you should see the old git ssh user's identities.

You can flush the identities using ssh-add -D or ssh-add -d or reload the ssh-agent using:

eval "$(ssh-agent -s)"
ssh-add