Key-based login into SSH for restricting remote access

Even though SSH login is protected by using passwords for the user account, we can make it more secure by using key-based authentication into SSH.

Getting ready

To see how key-based authentication works, we need two Linux systems (in our example, both are Ubuntu systems). We should have the OpenSSH server package installed on them.

How to do it...

To use key-based authentication, we need to create a pair of keys – a private key and a public key:

1. On the client or local system,  execute the following command to generate the SSH key pairs:

      ssh-keygen -t rsa

While creating the key, we can accept the default values or change them as we wish. It will also ask for a passphrase, for which you can choose anything or leave it blank.

2. The key-pair will be created in the location -~./ssh/. Change to this directory and then use the  ls -lcommand to see the details of the key files:

We can see that the id_rsa file can be read and written only by the...