Lose your SSH private key? Can it be recovered?

If you lose your private key, it cannot be recovered. The private key is a crucial part of the SSH key pair, and without it, you won’t be able to authenticate to any servers that rely on that key. Here are some steps you can take if you find yourself in this situation:

Immediate Actions

1. Generate a New SSH Key Pair: Create a new SSH key pair on your local machine. ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
2. Update Authorized Keys on Servers: Add the new public key to the ~/.ssh/authorized_keys file on all servers where the old key was used. You can use the ssh-copy-id command or manually append the new public key. ssh-copy-id user@remote_host
3. Remove the Old Public Key: Once the new key is added, remove the old public key from the ~/.ssh/authorized_keys file to prevent unauthorized access if the old key is found by someone else.

Preventive Measures

1. Backup Your Private Key: Always keep a secure backup of your private key. Store it in a safe location, such as an encrypted external drive or a secure cloud storage service.
2. Use a Passphrase: Protect your private key with a passphrase. This adds an extra layer of security, making it harder for someone to use your key if they find it.
3. Multiple Keys: Consider using different SSH keys for different servers or purposes. This way, losing one key doesn’t compromise access to all your servers.

Emergency Situations

In case of an emergency where you lose access to your servers due to a lost private key, having alternative access methods can be crucial:

1. Alternative Accounts: Ensure you have another user account with SSH access that can be used to update the authorized_keys file.
2. Out-of-Band Access: Use out-of-band management tools like IPMI, iLO, or a console server to gain access to the server and update the SSH keys.
3. Recovery Procedures: Document and regularly review your recovery procedures to ensure you can quickly regain access in case of key loss.

By taking these steps, you can mitigate the impact of losing your private key and ensure that you maintain secure access to your servers.