SSH to remote Linux machine using SSH key

How to do SSH to remote Linux machine using SSH key

Last Updated on February 18, 2023 by cscontents


In this article we will discuss step-by-step guide to log into remote Linux machine using SSH keys.


  • Knowledge on SSH
  • Basic Linux commands

Flow of steps

Below is a simple diagram which tells us the steps,

SSH doing steps using SSH keys

Step-by-step guide

In this example, we assume that we will log in from VM-1 to VM-2. Both are Linux machine.

Once you are logged into the VM-1 machine, follow the below steps.

Step 1: .ssh folder creation

Go inside the .ssh folder. Usually, .ssh folder exist in the user home directory. For example, if you logged into VM-1 using test_user, then .ssh folder will be in /home/test_user directory.

[test_user@RHEL01 ~]$ cd .ssh/

If .ssh folder does not exist, then you need to create one.

[test_user@RHEL01 ~]$ mkdir .ssh
[test_user@RHEL01 ~]$ cd .ssh/

Next we will run the below command ssh-keygen command.

[test_user@RHEL01 .ssh]$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/test_user/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/test_user/.ssh/id_rsa.
Your public key has been saved in /home/test_user/.ssh/
The key fingerprint is:
SHA256:********************************* test_user@RHEL01
The key's randomart image is:
+---[RSA 2048]----+
|BX*.   .==o      |
|++.B . oo+ .     |
|  B + o   o o    |
| o +   . o +     |
|  . o   E =      |
|   . o . o +     |
|    . .   .oo    |
|     .o.. +.     |
|     o++oo..     |

Step 2: Generate SSH public key

In the previous step the ssh-keygen command has generated two key –

  • One is public key (key is in the file) – we can share this key with other machines.
  • Another is private key (key is in the id_rsa file) – we need to safely keep this private key.

Now, file which has the public key of the machine VM-1, we need to copy that public key from this file.

[test_user@RHEL01 .ssh]$ pwd
[test_user@RHEL01 .ssh]$ cat

Step 3 & 4: Copy & Paste SSH public key

In this step we need to copy the public key from step-2 and log into the VM-2 and open the .ssh/authorized_keys file and paste it and save the file (if .ssh/authorized_keys file doesn’t exist then create one).

Step 5: SSH to remote machine

In this step we will try to ssh from VM-1 to VM-2 by running the below command.

[test_user@RHEL01 .ssh]$ ssh ubuntu@
The authenticity of host ' (' can't be established.
ECDSA key fingerprint is **************************************************.
Are you sure you want to continue connecting (yes/no/[fingerprint])?

Here in the above command, we are logging into VM-2 (having IP: with ubuntu user. You need to replace the above IP with your IP.

After step-5 we have two option –

  1. We can go with ‘yes’ option, and you will be able to log in.
  2. If we want to avoid the above situation where we need to enter yes/no, in that case we need to edit /etc/ssh/ssh_config file on VM-1. Here we have two option –
    • We can go with StrictHostKeyChecking no OR StrictHostKeyChecking accept-new


Thank You.


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