How do you set-up SSH with RSA public key authentication?

Step 1: Create Authentication SSH-Kegen Keys on – (192.168.1.1)

First login into server 192.168.1.1 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:

af:bc:25:72:d4:04:65:d9:5d:11:f0:eb:1d:89:50:4c tecmint@tecmint.com

The key's randomart image is:

+--[ RSA 2048]----+

|        ..oooE.++|

|         o. o.o  |

|          ..   . |

|         o  . . o|

|        S .  . + |

|       . .    . o|

|      . o o    ..|

|       + +       |

|        +.       |

+-----------------+

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 agilis as user and create .ssh directory under it, using following command.

[tecmint@tecmint ~]$ ssh agilis@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.

agilis@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 agilis‘s .ssh directory as a file name authorized_keys.

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

agilis@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 agilis@192.168.1.2 "chmod 700 .ssh; chmod 640 .ssh/authorized_keys"

agilis@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 agilis user from server 192.168.1.1 as tecmint user without password.

[tecmint@tecmint ~]$ ssh agilis@192.168.1.2