SSH Password less Login Using SSH Keygen

To configure SSH Passwordless Login Using SSH Keygen.

Find My Scenario to configure.

SSH Client : 192.168.1.193 ( CentOS 7 )
SSH Remote Host : 192.168.1.47 ( CentOS 7 )

Step 1: Create Authentication SSH-Kegen Keys on – (192.168.1.193 – Client)

First login into server 192.168.1.193 with user root and generate a pair of public keys using following command.

[root@gcdc-nms opt]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): /root/.ssh/rsync_key
Enter passphrase (empty for no passphrase): [Hit Enter]
Enter same passphrase again: [Hit Enter]
Your identification has been saved in /root/.ssh/rsync_key.
Your public key has been saved in /root/.ssh/rsync_key.pub.
The key fingerprint is:
SHA256:9hAlaN2gBCOmbIVv4QcGOiMSZp9yIHcVFgeWvHizo/4 root@gcdc-nms.localdomain
The key's randomart image is:
+---[RSA 2048]----+
|o=*.++OB+o.      |
|**+*.==o.o.      |
|B+++oo...        |
|+oo+..+  .       |
|  . .. oS        |
|      o. o       |
|     . .  .      |
|    .            |
|   ...E          |
+----[SHA256]-----+

Step 2: Create .ssh Directory on – 192.168.1.47 (Server)

# ssh root@192.168.1.47 mkdir -p .ssh

Step 3: Upload Generated Public Keys to – 192.168.1.47 (Go to 192.168.1.193 – Client)

# cat .ssh/id_rsa.pub | ssh root@192.168.1.47 'cat >> .ssh/authorized_keys'

Step 4: Set Permissions on – 192.168.1.47 (Server)

# ssh root@192.168.1.47 "chmod 700 .ssh; chmod 640 .ssh/authorized_keys"

Step 5: Login from 192.168.1.193 (Client) to 192.168.1.47 (Server) Server without Password

# ssh root@192.168.1.47

Enable SSH for root user on Ubuntu

To enable root Login, first assign the password for root user.

#sudo passwd root                -/enter new password for root user here.

Directly copy and paste this below lines in command prompt, to set ssh to allow root logins.

sed -i 's/Authentication:/#Authentication:/g' /etc/ssh/sshd_config sed -i 's/LoginGraceTime/#LoginGraceTime/g' /etc/ssh/sshd_config sed -i 's/#PermitRootLogin yes/PermitRootLogin yes/g' /etc/ssh/sshd_config sed -i 's/PermitRootLogin without-password/#PermitRootLogin without-password/g' /etc/ssh/sshd_config sed -i 's/StrictModes yes/#StrictModes yes' /etc/ssh/sshd_config service ssh restart

Or you can also configure it by manually by editing configuration file as mentioned below.

#vim /etc/ssh/sshd_config

# Authentication:
#LoginGraceTime 120
PermitRootLogin yes
#PermitRootLogin without-password
#StrictModes yes

Comment lines as mentioned above.

Save and exit the file.

Now restart ssh service

#service ssh restart

Check from the client machine.