SSH free password login

step1 :  Create public and private keys using ssh-key-gen on local-host

$ssh-keygen

step 2: Copy the public key to remote-host using ssh-copy-id

$ssh-copy-id -i ~/.ssh/id_rsa.pub remote-host

step 3: login remote host and change file permission

Change the permissions of .ssh to 700

$chmod 700 .ssh

Change the permissions of .ssh/authorized_keys to 640

$chmod 640 .ssh/authorized_keys

step 4: login from local host

ssh remote-host

(Optional) Alias for remote-host name

In local host

$vi .ssh/config

and add following lines

    Host short-name

    Hostname remote-host-name

    User your_user_name

    Port your_remote_host _port

Reference:

https://www.thegeekstuff.com/2008/11/3-steps-to-perform-ssh-login-without-password-using-ssh-keygen-ssh-copy-id/

http://www.linuxproblem.org/art_9.html

https://ostechnix.com/how-to-create-ssh-alias-in-linux/