You know the annoyence when SSH again and again asks you to enter the password?

Well, SSH does not allow caching of passwords. Caching would be nonsense since all the security of SSH would then be gone. But you can use RSA to create a private/public pair of keys and send the remote host the public key of your server.

First, we create the key pair:

ssh-keygen -t rsa

The last step of the key creation is the passphrase. Since the purpose of this is to not enter a password, hence being able to create batch jobs, just hit “Enter” twice, leaving them blank.

Then we’ll have to copy the public key to the remote host:

1. First create directory for SSH if not existent

   ssh root@example.com "mkdir .ssh; chmod 600 .ssh"

2. Then we have to copy the public key of our machine to the remote server

   scp ~/.ssh/id_rsa.pub root@example.com:~/.ssh/authorized_keys2

   (Ensure authorized_keys2 does not exist on remote host!)