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Archive for March, 2017

Using SSH keys provide a more secure way of logging into a remote computer when compared to password authentication, and today I will walk you through how we can achieve this in 3 simple steps

For this demo I will be configuring SSH key authentication for the user account accountsguru to connect to the remote system mylinuxlab.net, accessing remotely from my local computer sraavi.

  • user account: accountsguru
  • local computer: sraavi
  • remote system: mylinuxlab.net

Prerequisite: User accountsguru must be having an account already existing in the remote system mylinuxlab.net and authorized to access remotely.

Step1: Generate SSH public-private key pair

Logon to the local computer with the user account for which we want to create the SSH key pair, and run the following command

ssh-keygen

Below is the output generated. If you watch closely, in line 3 we are prompted to chose a directory and I accepted the default here, and in the next line we are prompted to enter a passphrase, which is to protect your private key. Passphrase adds an additional security layer because if in case a hacker got access to your private key he/she won’t be able to make any use as the private key is passphrase protected. Since we are doing a demo here I skipped the passphrase

[accountsguru@sraavi ~]$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/accountsguru/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/accountsguru/.ssh/id_rsa.
Your public key has been saved in /home/accountsguru/.ssh/id_rsa.pub.
The key fingerprint is:
7b:54:3e:f8:33:31:8e:70:81:f1:a3:4d:e2:52:c3:0b accountsguru@sraavi
The key's randomart image is:
+--[ RSA 2048]----+
| . |
| . + |
| E * = . |
| + B * |
| . S = = |
| . = + + |
| . o = |
| . o |
| |
+-----------------+

From the output above, line 6 is our private key, and line 7 is the public key.

Step2: Copy the public key to the remote system

Now, copy the public key from your local computer to the remote system using the below command

ssh-copy-id accountsguru@mylinuxlab.net

Note that it will prompt to enter the password to access the remote computer, and here is how the result looks like

[accountsguru@sraavi ~]$ ssh-copy-id accountsguru@mylinuxlab.net
/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
accountsguru@mylinuxlab.net's password:
Number of key(s) added: 1

From the above two steps we’ve successfully generated key pair and configured the user account accountsguru to access remotely using SSH

Step3: Connect to the remote system using SSH

Now let’s try logging into the remote server using SSH with the following command

ssh accountsguru@mulinuxlab.net

And, here is how it looks after making a successful connection..

[accountsguru@sraavi ~]$ ssh accountsguru@mylinuxlab.net
Last login: Fri Dec 9 19:28:33 2016 from 172.110.22.205
[accountsguru@mylinuxlab ~]$

To exit the remove server you can press tilda followed by dot (~.) and usually we won’t see the characters when we type them, but the session will terminate immediately

[accountsguru@mylinuxlab ~]$ Connection to mylinuxlab.net closed.

Hope this helps! If you have any feedback or a question, please leave it in the comment section below.

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