To access a Linux server with SSH and configure key pairs, follow these steps:
Generate a new key pair on your local machine (if you don't already have one) using the ssh-keygen command. This will create two files: a private key (usually stored in ~/.ssh/id_rsa) and a public key (stored in ~/.ssh/id_rsa.pub).
Copy the public key to the server using the ssh-copy-id command. This will add your public key to the authorized_keys file on the server, allowing you to authenticate using your private key.
ssh-copy-id user@server_address
If ssh-copy-id is not installed on your local machine, you can manually copy the contents of the public key file to the authorized_keys file on the server using an editor or the following command:
cat ~/.ssh/id_rsa.pub | ssh user@server_address "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"
Secure the private key on your local machine by setting the correct permissions:
chmod 600 ~/.ssh/id_rsa
Connect to the server using SSH, specifying the private key file with the -i option:
ssh -i ~/.ssh/id_rsa user@server_address
If your key file is named something other than id_rsa, replace id_rsa in the above command with the name of your key file.
That's it! You should now be able to access your Linux server using SSH with key pairs.