How to fix 'Permission denied (publickey)' SSH error

The SSH error 'Permission denied (publickey)' is one of the most common errors engineers hit. It means the SSH server rejected your authentication attempt. Here's exactly how to diagnose and fix it.

What causes this error

SSH authentication fails for a few common reasons: the wrong private key is being used, the private key file has incorrect permissions, the public key isn't in the remote server's authorized_keys file, or the SSH agent isn't running.

Step 1 — Check your private key permissions

SSH is strict about file permissions. If your private key is readable by others, SSH will refuse to use it.

chmod 600 ~/.ssh/id_rsa
chmod 700 ~/.ssh

Step 2 — Verify the public key is on the remote server

Your public key must be in ~/.ssh/authorized_keys on the remote host. Use ssh-copy-id to add it automatically:

ssh-copy-id -i ~/.ssh/id_rsa.pub user@host

Step 3 — Check which key SSH is trying

Run SSH with verbose output to see exactly what's happening:

ssh -vvv user@host

Step 4 — Add your key to the SSH agent

If your key has a passphrase and the agent isn't running, authentication will silently fail:

eval $(ssh-agent)
ssh-add ~/.ssh/id_rsa

Still stuck?

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