How to setup SSH Passwordless Login in Linux ?

 Setup SSH Passwordless Login in Linux for oracle user 

Source server : 10.1.1.1

Target server : 10.1.1.2

Genrate SSH key pair 

[oracle@10.1.1.1]$ ssh-keygen

Generating public/private rsa key pair.

Enter file in which to save the key (/home/oracle/.ssh/id_rsa):

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in /home/oracle/.ssh/id_rsa.

Your public key has been saved in /home/oracle/.ssh/id_rsa.pub.

The key fingerprint is:

SHA256:CQIzV4K1UyZ/7WmRtLTyPb1N3EHRXoZj4W09bbcQtDk oracle@ip-10.1.1.1.ec2.internal

The key's randomart image is:

+---[RSA 3072]----+

|  +o=.+   o .o.=o|

|  .= B   + + .O.*|

|    + o o *  E.*O|

|     o o = + .o+B|

|        S = o ..+|

|         .   . + |

|              . .|

|                 |

|                 |

+----[SHA256]-----+

[oracle@10.1.1.1]$

[oracle@10.1.1.1]$

[oracle@10.1.1.1]$

Upload SSH Key to target server – 10.1.1.2

ssh-copy-id oracle@10.1.1.2

[oracle@10.1.1.1]$

[oracle@10.1.1.1]$ ssh-copy-id oracle@10.1.1.2

/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/home/oracle/.ssh/id_rsa.pub"

The authenticity of host '172.31.21.233 (172.31.21.233)' can't be established.

ECDSA key fingerprint is SHA256:0cU9N1c6iec4IMkhQeT8s7FmzF04X0iLy8pytlr1JCk.

Are you sure you want to continue connecting (yes/no/[fingerprint])? yes

/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed

/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys

oracle@172.31.21.233's password:

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'oracle@10.1.1.2"

and check to make sure that only the key(s) you wanted were added.

[oracle@10.1.1.1]$

[oracle@10.1.1.1]$

Test and validate passwordless login 

Option:1

[oracle@10.1.1.1]$

[oracle@10.1.1.1]$

[oracle@10.1.1.1]$ ssh oracle@10.1.1.2

Register this system with Red Hat Insights: insights-client --register

Create an account or view all your systems at https://red.ht/insights-dashboard

Last login: Tue May 23 16:57:35 2023

[oracle@10.1.1.2 ~]$

[oracle@10.1.1.2 ~]$

Option:2

[oracle@10.1.1.1]$ ssh -l oracle 10.1.1.2

Register this system with Red Hat Insights: insights-client --register

Create an account or view all your systems at https://red.ht/insights-dashboard

Last login: Tue May 23 17:06:21 2023 from 10.1.1.1

[oracle@10.1.1.2]$