If you don’t want to enter password every time you login
into your linux system then you have to remove the password based
authentication and start using certificate based authentication. If you are an
AWS user then you must have seen that AWS provides key based authentication for
linux operating systems. You use the
private key to authenticate yourself to the linux machine hosted in the AWS
cloud.
Let’s start the drama
Step 1: Key Pair
Generation
For generating key pair you can use puttygen.
Open puttygen -> Click
Generate button -> move mouse over the blank area shown in the figure below
Save the public and private key by pressing the Save Public Key and Save Private Key button.
After saving the public and private keys go to Conversion file menu and press Export Openssh key and save that key somewhere in your hard disk.
Step 2: Exporting keys to liunx server.
In this step we will export the keys in linux host.
Login to the linux server by putty or whatever way you
prefer. I’ll recommend putty and ssh.
Now, create a directory .ssh if not exist, in the home directory of the
user for which you want to allow key based authentication. For example: for y user the directory path
will be /home/y/.ssh.
Now create a file in .ssh directory with name as id_dsa
Paste the openssh key file you generated using putty in this
id_dsa file and then change the
permission of id_dsa to 600
After this on the terminal inside .ssh directory run the
commands as shown below
Now you have both public and private key as id_dsa.pub and
id_dsa.
Now create a file authorized_keys
in the same directory.
And paste the data of id_dsa.pub
file into authorized_keys file.
Step 3: Setting Authentication method
In this step we will set up key based method as the
authentication method.
Open file /etc/ssh/sshd_config,
search for PasswordAuthentication, remove the # from the beginning of the line
and type no in place of yes and save and close the file.
Now you are done with the configuration .
Restart the ssh service and now try using the
private key file for authentication from putty, this is the private key you
generated after creation of the key pair.
