Ssh Key Generation Use Linux

Posted : admin On 15.04.2020

Jun 22, 2012 SSH keys provide a more secure way of logging into a virtual private server with SSH than using a password alone. With SSH keys, users can log into a server without a password. This tutorial explains how to generate, use, and upload an SSH Key Pair.

  1. 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.
  2. Jun 22, 2012  SSH keys provide a more secure way of logging into a virtual private server with SSH than using a password alone. With SSH keys, users can log into a server without a password. This tutorial explains how to generate, use, and upload an SSH Key Pair.
I recently read that SSH keys provide a secure way of logging into a Linux and Unix-based server. How do I set up SSH keys on a Linux or Unix based systems? In SSH for Linux/Unix, how do I set up public key authentication?
This page explains a public key and shows you how to set up SSH keys on a Linux or Unix-like server. I am assuming that you are using Linux or Unix-like server and client with the following software:
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  • OpenSSH SSHD server
  • OpenSSH ssh client and friends on Linux (Ubuntu, Debian, {Free,Open,Net}BSD, RHEL, CentOS, MacOS/OSX, AIX, HP-UX and co).

What is a public key authentication?

OpenSSH server supports various authentication schema. The two most popular are as follows:

  1. Passwords based authentication
  2. Public key based authentication. It is an alternative security method to using passwords. This method is recommended on a VPS, cloud, dedicated or even home based server.

How to set up SSH keys

Steps to setup secure ssh keys:

  1. Create the ssh key pair using ssh-keygen command.
  2. Copy and install the public ssh key using ssh-copy-id command on a Linux or Unix server.
  3. Add yourself to sudo or wheel group admin account.
  4. Disable the password login for root account.
  5. Test your password less ssh keys login using ssh user@server-name command.

Let us see all steps in details.

How do I set up public key authentication?

You must generate both a public and a private key pair. For example:
Where,

  • server1.cyberciti.biz – You store your public key on the remote hosts and you have an accounts on this Linux/Unix based server.
  • client1.cyberciti.biz – Your private key stays on the desktop/laptop/ computer (or local server) you use to connect to server1.cyberciti.biz server. Do not share or give your private file to anyone.

In public key based method you can log into remote hosts and server, and transfer files to them, without using your account passwords. Feel free to replace server1.cyberciti.biz and client1.cyberciti.biz names with your actual setup. Enough talk, let’s set up public key authentication. Open the Terminal and type following commands if .ssh directory does not exists:

1: Create the key pair

On the computer (such as client1.cyberciti.biz), generate a key pair for the protocol.

Sample outputs:

You need to set the Key Pair location and name. I recommend you use the default location if you do not yet have another key there, for example: $HOME/.ssh/id_rsa. You will be prompted to supply a passphrase (password) for your private key. I suggest that you setup a passphrase when prompted. You should see two new files in $HOME/.ssh/ directory:

  1. $HOME/.ssh/id_rsa– contains your private key.
  2. $HOME/.ssh/id_rsa.pub – contain your public key.

Optional syntax for advance users

The following syntax specifies the 4096 of bits in the RSA key to creation (default 2048):
$ ssh-keygen -t rsa -b 4096 -f ~/.ssh/vps-cloud.web-server.key -C 'My web-server key'
Where,

  • -t rsa : Specifies the type of key to create. The possible values are “rsa1” for protocol version 1 and “dsa”, “ecdsa”, “ed25519”, or “rsa” for protocol version 2.
  • -b 4096 : Specifies the number of bits in the key to create
  • -f ~/.ssh/vps-cloud.web-server.key : Specifies the filename of the key file.
  • -C 'My web-server key' : Set a new comment.

2: Install the public key in remote server

Use scp or ssh-copy-id command to copy your public key file (e.g., $HOME/.ssh/id_rsa.pub) to your account on the remote server/host (e.g., nixcraft@server1.cyberciti.biz). To do so, enter the following command on your client1.cyberciti.biz:

OR just copy the public key in remote server as authorized_keys in ~/.ssh/ directory:

A note about appending the public key in remote server

On some system ssh-copy-id command may not be installed, so use the following commands (when prompted provide the password for remote user account called vivek) to install and append the public key:

3: Test it (type command on client1.cyberciti.biz)

The syntax is as follows for the ssh command:

Or copy a text file called foo.txt:

You will be prompted for a passphrase. To get rid of passphrase whenever you log in the remote host, try ssh-agent and ssh-add commands.

What are ssh-agent and ssh-add, and how do I use them?

To get rid of a passphrase for the current session, add a passphrase to ssh-agent and you will not be prompted for it when using ssh or scp/sftp/rsync to connect to hosts with your public key. The syntax is as follows:

Type the ssh-add command to prompt the user for a private key passphrase and adds it to the list maintained by ssh-agent command:

Enter your private key passphrase. Now try again to log into user@server1.cyberciti.biz and you will not be prompted for a password:

One can list public key parameters of all identities with the -L option:
ssh-add -L
Deleting all private keys from the ssh-agent can be done with the -D option as follows:
ssh-add -D
When you log out kill the ssh agent, run:
kill $SSH_AGENT_PID
You can also add something like the below to your shell startup to kill ssh-agent at logout:
trap 'kill $SSH_AGENT_PID' 0

4: Disable the password based login on a server

Login to your server, type:

Edit /etc/ssh/sshd_config on server1.cyberciti.biz using a text editor such as nano or vim:

Warning: Make sure you add yourself to sudoers files. Otherwise you will not able to login as root later on. See “How To Add, Delete, and Grant Sudo Privileges to Users on a FreeBSD Server” for more info.

$ sudo vim /etc/ssh/sshd_config
OR directly jump to PermitRootLogin line using a vim text editor:
$ sudo vim +/PermitRootLogin /etc/ssh/sshd_config
Find PermitRootLogin and set it as follows:

Save and close the file. I am going to add a user named vivek to sudoers on Ubuntu Linux:
# adduser vivek
Finally, reload/restart the sshd server, type command as per your Linux/Unix version:

5: How to add or replace a passphrase for an existing private key?

To to change your passphrase type the following command:
ssh-keygen -p

6: How do I backup an existing private/public key?

Just copy files to your backup server or external USB pen/hard drive:

How do I protect my ssh keys?

  1. Always use a strong passphrase.
  2. Do not share your private keys anywhere online or store in insecure cloud storage.
  3. Restrict privileges of the account.

How do I create and setup an OpenSSH config file to create shortcuts for servers I frequently access?

See how to create and use an OpenSSH ssh_config file for more info.

Conclusion

This page explained how to set up ssh keys for authentication purposes. For more info see the following resources:

  • Man pages – ssh-keygen(1)
  • OpenSSH project homepage here.

And, there you have it, ssh set up with public key based authentication for Linux or Unix-like systems.

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Ssh Key Generation Use Linux Download

Overview

Automate Schedule allows secure file transfer protocol (SFTP) using public/private key encryption instead of a username/password combination. To use this feature, you must create secure shell (SSH) keys that can be used by the SFTP client on the Automate Schedule agent.

Automate Schedule requires that private SSH keys be stored in OpenSSH (OpenBSD secure shell) format. On Windows, you can use PuTTYgen (www.putty.org) to generate the keys in the proper format. On UNIX and Linux, you can use ssh-keygen from OpenSSH (www.openssh.com). The following sections describe how to generate the SSH keys.

Windows

If you're currently using PuTTY for SFTP transfers from your Windows system, the auxiliary program, PuTTYgen, can be used to convert an existing key (that's saved in .ppk format) for use with Automate Schedule. Or PuTTYgen can be used to create a new key.

To convert an existing .ppk key to be compatible with Automate Schedule:

  1. Open PuTTYgen (PuTTY Key Generator).
  2. Click Load.
  3. Select your existing .ppk file and click Open.
  4. After the key is loaded, select Conversions > Export OpenSSH Key. This saves the private key to the correct file format for use with Automate Schedule.
  5. If there is a warning about saving without a passphrase, click Yes.
  6. Save the OpenSSH key in a location that can be accessed by the Automate Schedule jobs that will be using the key. A typical location for storing private keys like this would be in the user's home directory inside an .ssh directory. For example: 'c:usersmyuser.sshid_rsa'.
  7. Close PuTTYgen.
  8. When creating or editing a file transfer system object in Automate Schedule, select SFTP as the Protocol, select an Authentication Type of Public/Private Key, and reference the private key you just converted in the Private Key File Path on Agent. See the help on creating file transfer systems in Automate Schedule for more information.

To generate a new key that's compatible with Automate Schedule:

Generate csr from existing private key openssl. Mar 30, 2015  You can do this with these steps: 1. Type the following command in an open terminal window on your computer to display the list of curves supported by your version of OpenSSL. Once you have selected a curve, then you can use the following command to create the private key file. Generate the CSR code and Private key for your certificate by running this command: openssl req -new -newkey rsa:2048 -nodes -keyout server.key -out servercsr.txt Note: server.key and servercsr.txt are the Private key and the CSR code files. I am using the following command in order to generate a CSR together with a private key by using OpenSSL: openssl req -new -subj '/CN=sample.myhost.com' -out newcsr.csr -nodes -sha512. The following instructions will guide you through the CSR generation process on Nginx (OpenSSL). To learn more about CSRs and the importance of your private key, reference our Overview of Certificate Signing Request article. If you already generated the CSR and received your trusted SSL certificate, reference our SSL Installation Instructions and disregard the steps below.

  1. Open PuTTYgen (PuTTY Key Generator).
  2. Select SSH-2 RSA in the Parameters section at the bottom of the page. Set the Number of bits in a generated key to '2048'.
  3. Click Generate. Move your mouse over the blank area in PuTTYgen to generate randomness for the key generation. The progress bar moves as you're moving the mouse.
    After the key is generated, the public part of the key is displayed under Public key for pasting into authorized_keys file. This can be copied and pasted to the correct file on the server or copied and pasted into a text file that can be moved to the SSH server system.
  4. Type a Key comment, if you want to save one with the new key.
  5. Optionally, type a Key passpharase. Type it again to confirm it.
  6. Select Conversions > Export OpenSSH Key. This saves the private key to the correct file format for use with Automate Schedule.
  7. If there's a warning about saving without a passphrase click Yes.
  8. Save the OpenSSH key in a location that can be accessed by the Automate Schedule jobs that will be using the key. A typical location for storing private keys like this would be in the user's home directory inside an .ssh directory. For example, 'c:Usersmyuser.sshid_rsa'.
  9. Close PuTTYgen.
  10. When creating or editing a file transfer system object in Automate Schedule, select SFTP as the Protocol, select an Authentication Type of Public/Private Key, and reference the private key you just converted in the Private Key File Path on Agent. See the help on creating file transfer systems in Automate Schedule for more information.

UNIX/Linux

Linux How To Share Ssh Keys

UNIX and Linux users can use the OpenSSH program ssh-keygen to generate private/public keys. Private keys created by ssh-keygen can also be used on Automate Schedule Windows agents with no modification.

Ssh Key Generation Use Linux Free

To generate a new key that is compatible with Automate Schedule:

Ssh Key Generation Use Linux Windows 10

  1. As the user who will be issuing SFTP requests from an Automate Schedule job on an agent, run the following command:
    ssh-keygen -t rsa -b 2048 -f /home/myuser/.ssh/mykey
    In this example, the private key will be stored in /home/myuser/.ssh/mykey and the public key will be stored in /home/myuser/.ssh/mykey.pub.
  2. Optionally set a passphrase during key generation.
  3. When creating or editing a file transfer system object in Automate Schedule, select SFTP as the Protocol, select an Authentication Type of Public/Private Key, and reference the private key you just converted in the Private Key File Path on Agent. See the help on creating file transfer systems in Automate Schedule for more information.