Password less SSH

Step 1: Create Authentication SSH-Kegen Keys onem which you want to login from

first login into server 192.168.1.1 with user tecmint and generate a pair of public keys using following command.

$ ssh-keygen -t rsa

Generating public/private rsa key pair.
Enter file in which to save the key (/home/tecmint/.ssh/id_rsa): [Press enter key]
Created directory '/home/tecmint/.ssh'.
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Press enter key]
Your identification has been saved in /home/tecmint/.ssh/id_rsa.
Your public key has been saved in /home/tecmint/.ssh/id_rsa.pub.
The key fingerprint is:

Step 2: Create .ssh Directory on – 192.168.1.2

Use SSH from server 192.168.1.1 to connect server 192.168.1.2 using sanjay as user and create .ssh directory under it, using following command.

[tecmint@tecmint ~]$ ssh sanjay@192.168.1.2 mkdir -p .ssh

The authenticity of host '192.168.1.2 (192.168.1.2)' can't be established.
RSA key fingerprint is d6:53:94:43:b3:cf:d7:e2:b0:0d:50:7b:17:32:29:2a.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.1.2' (RSA) to the list of known hosts.
sanjay@192.168.1.2's password: [Enter Your Password Here]

Step 3: Upload Generated Public Keys to – 192.168.1.2

Use SSH from server 192.168.1.1 and upload new generated public key (id_rsa.pub) on server 192.168.1.2 under sanjay‘s .ssh directory as a file name authorized_keys.

[tecmint@tecmint ~]$ cat .ssh/id_rsa.pub | ssh sanjay@192.168.1.2 'cat >> .ssh/authorized_keys'

sanjay@192.168.1.2's password: [Enter Your Password Here]

Step 4: Set Permissions on – 192.168.1.2

Due to different SSH versions on servers, we need to set permissions on .ssh directory and authorized_keys file.

[tecmint@tecmint ~]$ ssh sanjay@192.168.1.2 "chmod 700 .ssh; chmod 640 .ssh/authorized_keys"

sanjay@192.168.1.2's password: [Enter Your Password Here]

Step 5: Login from 192.168.1.1 to 192.168.1.2 Server without Password

From now onwards you can log into 192.168.1.2 as sanjay user from server 192.168.1.1 astecmint user without password.

[tecmint@tecmint ~]$ ssh sanjay@192.168.1.2