SSH without Password in linux

SSH Linux:

We can SSH Linux or log in between two Linux based machine without a password. There are many mechanisms to utilize this feature in Linux.  Below is of one of the methods, which is fast and simple i.e using SSH -keygen

Terms used:

ssh-keygen  – creates the public and private keys.

ssh-copy-id  – copies the local-host’s public key to the remote host’s authorized_keys file. ssh-copy-id also assigns proper permission to the remote-host’s home, ~/.ssh, and ~/.ssh/authorized_keys.

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Idea is to do remote login (from machine 1 i.e your machine) to another machine (machine 2). Some prerequisite  for the ssh are as below:

• Ping should be available between two machines
• the ssh port should be enabled and opened
• check for the firewall. if the firewall is stopping for any remote login then we need to configure firewall accordingly.
• manually do ssh with a prompt password to verify ssh is working good and if all the points above are verified then follow below steps

Steps followed for SSH in Linux :

Step 1: using ssh -keygen

Create a public and private key using ssh-keygen on your machine 1

root@inertiagroups:~#
root@inertiagroups:~# ssh-keygen

Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
e7:57:8b:5d:ca:3f:37:b2:18:9d:e4:1e:ea:46:88:53 root@inertiagroups

Step 2:

Copy the public key as created to remote machine 2

root@inertiagroups:~# ssh-copy-id -i ~/.ssh/id_rsa.pub remote-host
ssh: Could not resolve hostname remote-host: Name or service not known
root@inertiagroups:~# ssh-copy-id -i ~/.ssh/id_rsa.pub machine2-IP
root@104.37.169.247’s password:
Now try logging into the machine, with “ssh ‘IP‘”, and check in:

~/.ssh/authorized_keys

to make sure we haven’t added extra keys that you weren’t expecting.

* replace machine2 IP with your Machine 2 IP

Step 3:

Settings for the login without password in Linux base system is done now.

Try login from your machine 1 to machine 2 using command:
root@inertiagroups:~# ssh machine2-IP
Last login: Sun May 15 00:21:35 2016 from 103.232.233.104
[root@server1 ~]# [prompt of machine2]

we could log in without any password requirement.

give a try with this and let me know if this was helpful !!

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