csWiki

the wiki of cscosine

Project maintained by cscosine Hosted on GitHub Pages — Theme by mattgraham

Table Of Contents

Clean SSH + Git Multi-Account Setup (Delete Everything and Start Fresh)

This guide resets all SSH keys and rebuilds a clean multi-account Git setup (e.g., personal + work).
It also includes how to verify and fix repository remotes to ensure the correct SSH identity is used.

1. Remove All Existing SSH Keys

First inspect your current SSH directory:

ls -al ~/.ssh

If you want a complete reset:

rm -rf ~/.ssh
mkdir ~/.ssh
chmod 700 ~/.ssh

This removes:

2. Clear SSH Agent

Remove any keys currently loaded in the SSH agent:

ssh-add -D

Verify it’s empty:

ssh-add -l

Expected result:

The agent has no identities.

3. Generate One SSH Key Per Git Account

Using ed25519 is recommended.

Personal account

ssh-keygen -t ed25519 -C "personal@email.com"

Save as:

~/.ssh/id_ed25519_personal

Work account

ssh-keygen -t ed25519 -C "work@email.com"

Save as:

~/.ssh/id_ed25519_work

Resulting files:

~/.ssh/id_ed25519_personal
~/.ssh/id_ed25519_personal.pub
~/.ssh/id_ed25519_work
~/.ssh/id_ed25519_work.pub

4. Create SSH Config for Multiple Accounts

Edit the SSH config file:

nano ~/.ssh/config

Example configuration:

Host github-personal
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_ed25519_personal
  IdentitiesOnly yes

Host github-work
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_ed25519_work
  IdentitiesOnly yes

Set proper permissions:

chmod 600 ~/.ssh/config

This creates SSH aliases:

These force Git to use the correct key.

5. Add Keys to SSH Agent

ssh-add ~/.ssh/id_ed25519_personal
ssh-add ~/.ssh/id_ed25519_work

Verify:

ssh-add -l

You should see both keys listed.

6. Add Public Keys to Your Git Accounts

Print the public key:

cat ~/.ssh/id_ed25519_personal.pub

Add it to:

GitHub → Settings → SSH and GPG keys

Repeat for the work key:

cat ~/.ssh/id_ed25519_work.pub

Add it to the work account.

7. Test Authentication

Test each SSH identity.

Personal

ssh -T git@github-personal

Work

ssh -T git@github-work

Expected message:

Hi username! You've successfully authenticated.

8. Clone Repositories Using the Correct Host

Use the SSH aliases defined earlier.

Personal repo

git clone git@github-personal:username/repo.git

Work repo

git clone git@github-work:company/repo.git

This ensures Git uses the correct SSH key automatically.

9. Verify Current Repository Remote

Inside any repository, check the configured remote:

git remote -v

Example output:

origin  git@github.com:username/repo.git (fetch)
origin  git@github.com:username/repo.git (push)

If you see git@github.com, then your SSH config alias is NOT being used.

Correct multi-account setup should look like:

origin  git@github-personal:username/repo.git

or

origin  git@github-work:company/repo.git

10. Fix an Incorrect Remote

To update the remote URL:

Personal repo

git remote set-url origin git@github-personal:username/repo.git

Work repo

git remote set-url origin git@github-work:company/repo.git

Verify the fix:

git remote -v

11. Verify Which SSH Key Is Used (Debug)

If authentication problems occur, run:

ssh -vT git@github-personal

or

ssh -vT git@github-work

Look for the line:

Offering public key: ~/.ssh/id_ed25519_personal

This confirms the correct key is being used.

12. Optional: Set Git Identity

Global default:

git config --global user.name "Your Name"
git config --global user.email "personal@email.com"

For work repositories:

git config user.email "work@email.com"

Verify:

git config --list

Result

You now have: