SSH Passwordless Login Using SSH Keygen

Step 1: Create Authentication SSH-Kegen Keys on – (

First login into server with user zetuser and generate a pair of public keys using following command.

[[email protected] ~]$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/zetuser/.ssh/id_rsa): [Press enter key]
Created directory '/home/zetuser/.ssh'.
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Press enter key]
Your identification has been saved in /home/zetuser/.ssh/id_rsa.
Your public key has been saved in /home/zetuser/.ssh/
The key fingerprint is:
5f:ad:40:00:8a:d1:9b:99:b3:b0:f8:08:99:c3:ed:d3 [email protected]
The key's randomart image is:
+--[ RSA 2048]----+
|        ..oooE.++|
|         o. o.o  |
|          ..   . |
|         o  . . o|
|        S .  . + |
|       . .    . o|
|      . o o    ..|
|       + +       |
|        +.       |

Step 2: Create .ssh Directory on –

Use SSH from server to connect server using zetuser2 as user and create .ssh directory under it, using following command.

[[email protected] ~]$ ssh [email protected] mkdir -p .ssh
The authenticity of host ' (' can't be established.
RSA key fingerprint is 45:0e:28:11:d6:81:62:16:04:3f:db:38:02:la:22:4e.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '' (ECDSA) to the list of known hosts.
[email protected]'s password: [Enter Your Password Here]

Step 3: Upload Generated Public Keys to –

Use SSH from server and upload new generated public key ( on server under zetuser2‘s .ssh directory as a file name authorized_keys.

[[email protected] ~]$ cat .ssh/ | ssh [email protected] 'cat >> .ssh/authorized_keys'
[email protected]'s password: [Enter Your Password Here]

Step 4: Set Permissions on –

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

[[email protected] ~]$ ssh [email protected] "chmod 700 .ssh; chmod 640 .ssh/authorized_keys"
[email protected]'s password: [Enter Your Password Here]

Step 5: Login from to Server without Password

From now onwards you can log into as zetuser2 user from server as zetuser1 user without password.

[[email protected] ~]$ ssh [email protected]