Add multiple SSH keys to the authorized_keys file to enable SSH authentication when connecting to a server.

multiple-ssh-authkeys.md

Step 1: Generate first ssh key Type the following command to generate your first public and private key on a local workstation. Next provide the required input or accept the defaults. Please do not change the filename and directory location.

workstation 1 $ ssh-keygen -t rsa

Finally, copy your public key to your remote server using scp

workstation 1 $ scp ~/.ssh/id_rsa.pub user@remote.server.com:.ssh/authorized_keys

Step 2: Generate next/multiple ssh key

1. Login to 2nd workstation
2. Download original the authorized_keys file from remote server using scp:

workstation 2 $ scp user@remote.server.com:.ssh/authorized_keys ~/.ssh

3. Now create the new pub/private key:

workstation 2 $ ssh-keygen -t rsa

4. Now you have new public key. APPEND this key to the downloaded authorized_keys file using cat command:

workstation 2 $ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys

5. Finally upload authorized_keys to remote server again:

workstation 2 $ scp ~/.ssh/authorized_keys user@remote.server.com:.ssh/

You can repeat step 2 for each user or workstations for remote server.

Step 3: Test your setup Now try to login from Workstation 1, 2 and so on to remote server. You should not be asked for a password:

workstation 1 $ ssh user@remote.server.com

workstation 2 $ ssh user@remote.server.com

Thanks for sharing. Clear and precise answer.

How does scp work without ssh key(public key) added to .ssh/authorized_keys ? You are doing scp before the key got apppended to the server

@madhusudan12 visit this link to understand how scp works https://linuxize.com/post/how-to-use-scp-command-to-securely-transfer-files/

Public keys on my Ubuntu have 644 permissions, and authoerized_keys 600 (without my having done anything to change them). Does scp in Step 1 result in authorized_keys having 644? Is that OK? I guess OK could mean two things. Will the machine not object? And OK from a security perspective. (I don't know anything. Just asking.)

Amazing! Thank you so much :)