Linux Generate Ssh Key Pair For User

Create Ssh Key Pair

Generating an SSH Key Pair on UNIX and UNIX-Like Platforms Using the ssh-keygen Utility UNIX and UNIX-like platforms (including Solaris and Linux) include the ssh-keygen utility to generate SSH key pairs. You can create a key pair for each user, and add the public key information from each key pair to the.ssh/authorizedkeys file for each user on your instance. Apr 02, 2019 Step One: Creation of the RSA Key Pair. The first step in the installation process is to create the key pair on the client machine, which would, more often than not, be your own system. Users need to use the following command: ssh-keygen -o -b 4096 -t rsa. The above command kicks off the SSH Key installation process for users. If the login is an non-interactive user utilized to perform utility tasks (e.g. Running running maine scripts on remote servers), then yes, you would probably generate the key for that user manually. Of course, that has its own security implications, but that's another story. Jul 17, 2017 To ssh using pem file there are few steps you have to follow 1.Generating Key Pairs. To generate an RSA key pair for version 2 of the SSH protocol, follow these steps: Generate an RSA key pair by typing the following at a shell prompt: $ ssh-keygen or $ ssh-keygen -t rsa -b 2048 -v.

Use the ssh-keygen command to generate a public/private authentication key pair. Authentication keys allow a user to connect to a remote system without supplying a password. Keys must be generated for each user separately. If you generate key pairs as the root user, only the root can use the keys.
Run it on your local computer to generate a 2048-bit RSA key pair, which is fine for most uses. Ssh-keygen The utility prompts you to select a location for the keys. By default, the keys are stored in the /.ssh directory with the filenames idrsa for the private key and idrsa.pub for the public key.

am a new RHEL 8 server sysadmin. How do I configure SSH public key-based authentication for RHEL (Red Hat Enterprise Linux) 8 server?
Introduction – SSH is an acronym for secure shell. It is a suite of cryptographic network protocol. It allows users to log in and transfer files securely over the unsecure network such as the Internet. OpenSSH is an implementation of SSH protocol on RHEL 8. You can log in using RHEL 8 user and password account. However, OpenSSH project recommends log in using a combination of a private and public SSH keys.

Sample set up for our RHEL 8 server

Where, Powershell generate certificate with private key address.

You generate a key pair on your Linux/Unix/macOS desktop.
Place the public key on RHEL 8 server.
One can unlock public key using a private key stored on your desktop with the help of ssh command.
When both the public and private key correct you can log in without a password.

How do I set up SSH keys on RHEL 8 server?

The procedure to set up SSH key on Red Hat Enteprise Linux 8 server:

On your local desktop type:
ssh-keygen
Install public key into remote RHEL 8 server using:
ssh-copy-id user@remote-RHEL8-server-ip
Use ssh for password less login:
ssh user@remote-RHEL8-server-ip

Let us see all commands and steps in details.

How to create the ed25519 or RSA key pair

The syntax is:
ssh-keygen -t ed25519 ssh-keygen -t rsa ssh-keygen -t rsa -b 4096 -f ~/.ssh/aws-lighsail.key -C 'My AWS SSH Keys' ssh-keygen -t ed25519 -f ~/.ssh/linode-usa-www1-vps.key -C 'My Linode SSH Keys for www'
Where,

-t rsa OR -t ed25519 : Specifies the type of key to create. The possible values “dsa”, “ecdsa”, “ed25519”, or “rsa” for SSH protocol version 2.
-b 4096 : Specifies the number of bits in the key to create.
-f~/.ssh/aws-lighsail.key : Specifies the filename of the key file.
-C -C 'My AWS SSH Keys' : Set a new comment.

I am going type the following command on my Ubuntu desktop to create the key pair:
$ ssh-keygen -t ed25519
I strongly recommend that you set up a passphrase when prompted.

How to copy the public key

Now our key paid generated and stored in ~/.ssh/ directory. You must copy a public SSH key file named ~/.ssh/id_ed25519.pub (or ~/.ssh/id_rsa.pub if you created RSA key) to the RHEL 8 server. Try the ssh-copy-id command as follows:
$ ssh-copy-id -i ~/.ssh/fileNameHere.pubuser@remote-RHEL8-server-ip
For example:
$ ssh-copy-id -i ~/.ssh/id_ed25519.pub vivek@192.168.2.211

How to log in using ssh and without a password

Now try logging into the machine, with the ssh command as follows:
$ ssh user@rhel-8-server $ ssh vivek@192.168.2.211
You should be able to log in without a password. If you set up a passphrase, unlock it as follows for your current session so that you don’t have to enter it every time you run ssh, sftp, scp, rsync and other commands:
$ ssh-agent $SHELL $ ssh-add

Optional settings for root user

Disable root user log in all together on RHEL 8 via ssh. Log in as root user on RHEL 8 and run following to add a user named vivek to wheel group:
# usermod -aG wheel vivek # id vivek
Allows users in group wheel can use sudo command to run all commands on RHEL 8 server. Next disable root user login by adding the following line to sshd_config:
# vi /etc/ssh/sshd_config
Disable the password for root login and only allow ssh keys based login:

Save and close the file. Reload the ssh server:
# systemctl reload sshd.service
For more info see “Top 20 OpenSSH Server Best Security Practices“.

Conclusion

You learned how to set up and use SSH keys to manage your RHEL 8 based server. For more info see OpenSSH man pages here.