Start by checking if you already have SSH keys generated on your local machine. Open your terminal and execute the following command:
ls -al ~/.ssh
Look for files named id_rsa
and id_rsa.pub
or id_ed25519
and id_ed25519.pub
. These are your private and public SSH keys, respectively.
If you find these files, you have existing SSH keys. If not, proceed to generate a new SSH key pair.
If no SSH keys exist, generate a new SSH key pair using the following command:
ssh-keygen -t ed25519 -C "your_email@example.com"
your_email@example.com
with your GitHub-associated email address.Enter
to accept the default file location (~/.ssh/id_ed25519
).If your system does not support Ed25519, use RSA with:
ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
Ensure that the SSH agent is running and add your private SSH key to it:
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519
If you used a different filename for your key, replace id_ed25519
with your key’s name.
To allow GitHub to recognize your machine, you need to add the public SSH key to your GitHub account. Follow these steps:
Copy your public key to the clipboard using:
cat ~/.ssh/id_ed25519.pub
Select and copy the output.
Log in to your GitHub account and navigate to Settings > SSH and GPG keys.
Click on New SSH key, provide a descriptive title (e.g., "Personal Laptop"), and paste your public key into the "Key" field.
Save the changes by clicking Add SSH key.
Verify that your SSH key is correctly set up by testing the connection:
ssh -T git@github.com
Upon successful authentication, you should see a message similar to:
Hi username! You've successfully authenticated, but GitHub does not provide shell access.
If you still encounter the Permission denied (publickey)
error, proceed to the next steps.
Ensure that your Git remote URL is using the correct SSH format. Check your remote URL with:
git remote -v
The output should display URLs starting with git@github.com:
. If you see https://
URLs instead, update them using:
git remote set-url origin git@github.com:username/repo.git
Replace username
and repo.git
with your GitHub username and repository name, respectively.
With the SSH key correctly configured and the remote URL verified, try cloning the repository again:
git clone git@github.com:keli/ctp-python.git
If the setup is correct, the cloning process should proceed without the previous permission error.
Using an incorrect SSH URL is a common cause of authentication failures. Always ensure that your repository URL follows the SSH format:
git@github.com:username/repository.git
If you have multiple SSH keys, Git might not be using the correct one. List the keys loaded in the SSH agent with:
ssh-add -l
If your desired key isn't listed, add it using:
ssh-add ~/.ssh/your_key_name
A misconfigured ~/.ssh/config
file can prevent Git from using the correct SSH key. Ensure your config file includes the following for GitHub:
Host github.com
HostName github.com
User git
IdentityFile ~/.ssh/id_ed25519
SSH requires specific file permissions for security reasons. Set the correct permissions using:
chmod 700 ~/.ssh
chmod 600 ~/.ssh/id_ed25519
chmod 644 ~/.ssh/id_ed25519.pub
Network proxies or firewalls might block SSH connections. If you're on a restricted network, consider switching to HTTPS for cloning:
git clone https://github.com/keli/ctp-python.git
Ensure that your GitHub account has the necessary permissions to access the repository, especially if it's private. You might need to request access from the repository owner.
If SSH continues to present challenges, you can use HTTPS to clone repositories. This method uses your GitHub username and password or a personal access token for authentication:
git clone https://github.com/keli/ctp-python.git
While HTTPS is often simpler, it requires entering credentials more frequently unless a credential manager is used.
If your SSH key pair is compromised or you suspect it's malfunctioning, regenerate a new pair and update GitHub with the new public key:
Generate a new SSH key:
ssh-keygen -t ed25519 -C "your_email@example.com"
Add the new key to the SSH agent and GitHub as previously described.
Protect your SSH keys with strong, unique passphrases to enhance security.
Periodically rotate your SSH keys to minimize security risks in case of key compromise.
Use different SSH keys for different devices or purposes to limit access scopes.
Never share your private SSH keys. Store them securely and back them up if necessary.
The Permission denied (publickey)
error is a common hurdle when working with GitHub repositories via SSH. By following the comprehensive steps outlined above, you can effectively troubleshoot and resolve this authentication issue. Ensuring your SSH keys are correctly set up, your Git remote URLs are accurate, and your network configurations are conducive will pave the way for seamless repository interactions.