Generate Ssh Key Pair Redhat

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Jun 06, 2014  Generate SSH Key Pair on CentOS SSH (Secure Shell) and SFTP (Secure FTP) support a very strong security model that can be used instead of the normal username and password authentication scheme. Generate Your Keys. Nov 30, 2018  Sample set up for our RHEL 8 server. Where, 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.

IGenerate Ssh Key Pair RedhatSsh 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.
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Sample set up for our RHEL 8 server


Where,

  • 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:

  1. On your local desktop type:
    ssh-keygen
  2. Install public key into remote RHEL 8 server using:
    ssh-copy-id user@remote-RHEL8-server-ip
  3. 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
Generate public key from private puttygen. 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.

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With a secure shell (SSH) key pair, you can create virtual machines (VMs) in Azure that use SSH keys for authentication, eliminating the need for passwords to sign in. This article shows you how to quickly generate and use an SSH public-private key file pair for Linux VMs. You can complete these steps with the Azure Cloud Shell, a macOS or Linux host, the Windows Subsystem for Linux, and other tools that support OpenSSH.

Note

VMs created using SSH keys are by default configured with passwords disabled, which greatly increases the difficulty of brute-force guessing attacks.

For more background and examples, see Detailed steps to create SSH key pairs.

For additional ways to generate and use SSH keys on a Windows computer, see How to use SSH keys with Windows on Azure.

Supported SSH key formats

Azure currently supports SSH protocol 2 (SSH-2) RSA public-private key pairs with a minimum length of 2048 bits. Other key formats such as ED25519 and ECDSA are not supported.

Create an SSH key pair

Use the ssh-keygen command to generate SSH public and private key files. By default, these files are created in the ~/.ssh directory. You can specify a different location, and an optional password (passphrase) to access the private key file. If an SSH key pair with the same name exists in the given location, those files are overwritten.

The following command creates an SSH key pair using RSA encryption and a bit length of 4096:

If you use the Azure CLI to create your VM with the az vm create command, you can optionally generate SSH public and private key files using the --generate-ssh-keys option. The key files are stored in the ~/.ssh directory unless specified otherwise with the --ssh-dest-key-path option. The --generate-ssh-keys option will not overwrite existing key files, instead returning an error. In the following command, replace VMname and RGname with your own values:

Provide an SSH public key when deploying a VM

To create a Linux VM that uses SSH keys for authentication, specify your SSH public key when creating the VM using the Azure portal, Azure CLI, Azure Resource Manager templates, or other methods:

If you're not familiar with the format of an SSH public key, you can display your public key with the following cat command, replacing ~/.ssh/id_rsa.pub with the path and filename of your own public key file if needed:

A typical public key value looks like this example:

If you copy and paste the contents of the public key file to use in the Azure portal or a Resource Manager template, make sure you don't copy any trailing whitespace. To copy a public key in macOS, you can pipe the public key file to pbcopy. Similarly in Linux, you can pipe the public key file to programs such as xclip.

The public key that you place on your Linux VM in Azure is by default stored in ~/.ssh/id_rsa.pub, unless you specified a different location when you created the key pair. To use the Azure CLI 2.0 to create your VM with an existing public key, specify the value and optionally the location of this public key using the az vm create command with the --ssh-key-values option. In the following command, replace VMname, RGname, and keyFile with your own values:

If you want to use multiple SSH keys with your VM, you can enter them in a space-separated list, like this --ssh-key-values sshkey-desktop.pub sshkey-laptop.pub.

SSH into your VM

With the public key deployed on your Azure VM, and the private key on your local system, SSH into your VM using the IP address or DNS name of your VM. In the following command, replace azureuser and myvm.westus.cloudapp.azure.com with the administrator user name and the fully qualified domain name (or IP address):

If you specified a passphrase when you created your key pair, enter that passphrase when prompted during the login process. The VM is added to your ~/.ssh/known_hosts file, and you won't be asked to connect again until either the public key on your Azure VM changes or the server name is removed from ~/.ssh/known_hosts.

Generate Ssh Key Pair Red Hat For Kids

If the VM is using the just-in-time access policy, you need to request access before you can connect to the VM. For more information about the just-in-time policy, see Manage virtual machine access using the just in time policy.

Generate Ssh Key

Next steps

Generate Ssh Key Windows

  • For more information on working with SSH key pairs, see Detailed steps to create and manage SSH key pairs.

  • If you have difficulties with SSH connections to Azure VMs, see Troubleshoot SSH connections to an Azure Linux VM.