PasswordLessAuthentication

PasswordLessAuthentication

My Setup Environment

SSH Client : 192.168.0.12 ( Fedora 21 )
SSH Remote Host : 192.168.0.11 ( CentOS 7 )

If you are dealing with number of Linux remote servers, then SSH Password-less login is one of the best way to automate tasks such as automatic backups with scripts, synchronization files using scp and remote command execution.
In this example we will setup SSH password-less automatic login from server 192.168.0.12 as usertecmint to 192.168.0.11 with user sheena.

Step 1: Create Authentication SSH-Kegen Keys on – (192.168.0.12)

First login into server 192.168.0.12 with user tecmint and generate a pair of public keys using following command.

tecmint@tecmint.com ~]$ 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:
5f:ad:40:00:8a:d1:9b:99:b3:b0:f8:08:99:c3:ed:d3 tecmint@tecmint.com
The key's randomart image is:
+--[ RSA 2048]----+
|        ..oooE.++|
|         o. o.o  |
|          ..   . |
|         o  . . o|
|        S .  . + |
|       . .    . o|
|      . o o    ..|
|       + +       |
|        +.       |
+-----------------+</span>

Create SSH RSA Key

Create SSH RSA Key

Step 2: Create .ssh Directory on – 192.168.0.11

Use SSH from server 192.168.0.12 to connect server 192.168.0.11 using sheena as user and create.ssh directory under it, using following command.

tecmint@tecmint ~]$ ssh sheena@192.168.0.11 mkdir -p .ssh
 
The authenticity of host '192.168.0.11 (192.168.0.11)' 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 '192.168.0.11' (ECDSA) to the list of known hosts.
sheena@192.168.0.11's password: Enter Your Password Here

Create SSH Directory Under User Home

Step 3: Upload Generated Public Keys to – 192.168.0.11

Use SSH from server 192.168.0.12 and upload new generated public key (id_rsa.pub) on server192.168.0.11 under sheena‘s.ssh directory as a file name authorized_keys.

tecmint@tecmint ~]$ cat .ssh/id_rsa.pub | ssh sheena@192.168.0.11 'cat >> .ssh/authorized_keys'</span>
 
sheena@192.168.1.2's password: >Enter Your Password Here

Upload RSA Key

Step 4: Set Permissions on – 192.168.0.11

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

tecmint@tecmint $ ssh sheena@192.168.0.11 "chmod 700 .ssh; chmod 640 .ssh/authorized_keys"
 
sheena@192.168.0.11's password: Enter Your Password Here

Set Permission on SSH Key

Set Permission on SSH Key

Step 5: Login from 192.168.0.12 to 192.168.0.11 Server without Password

From now onwards you can log into 192.168.0.11 as sheena user from server 192.168.0.12 as tecmintuser without password.

tecmint@tecmint $ ssh sheena@192.168.0.11

SSH Remote Passwordless Login

SSH Remote Passw