A Pre-Shared Key (PSK) or also known as a shared secret is a string of characters that is used as an authentication key in cryptographic processes. A PSK is shared before being used and is held by both parties to the communication to authenticate each other, usually before other authentication methods such as usernames and passwords are applied.
You can generate an SSH key pair directly in cPanel, or you can generate the keys yourself and just upload the public one in cPanel to use with your hosting account. When generating SSH keys yourself under Linux, you can use the ssh-keygen command. Wi-Fi Protected Access Pre-Shared Key (WPA-PSK) is a security mechanism used to authenticate and validate users on a wireless LAN (WLAN) or Wi-Fi connection. It is a variation of the WPA security protocol. WPA-PSK is also known as WPA2-PSK or WPA Personal.
It is commonly used in different types of Virtual Private Network (VPN) connections, wireless networks in a type of encryption known as WPA-PSK (Wi-Fi Protected Access Pre-Shared Key) and WPA2-PSK, and also in the EAP (Extensible Authentication Protocol Pre-Shared Key), and many others authentication mechanisms.
In this article, we will show you different ways to generate a strong Pre-Shared Key in Linux distributions.
1. Using OpenSSL Command
Linux A Pre-Shared Key (PSK) or also known as a shared secret is a string of characters that is used as an authentication key in cryptographic processes. A PSK is shared before being used. The VPN should be able to connect to two clients using two different pre-shared-keys. How can i setup this VPN to use and connect to the clients using the PSKs? I have tried to use this guide but can't seem to figure out why i need to generate a new PSK since i already have two sent from the clients. I heard openVPN is good. Does it support PSKs? They all work well depending of the IPSec server. There is even a GUI for VPNC that integrate into Ubuntu network manager. Official Cisco client is harder to install.
OpenSSL is a well-known and widely-used command-line tool used to invoke the various cryptography functions of OpenSSL’s crypto library from the shell. To generate a strong PSK use its rand sub-command which generates pseudo-random bytes and filter it through base64 encodings as shown.
2. Using GPG Command
GPG is a command-line tool to provide digital encryption and signing services using the OpenPGP standard. You can use its --gen-random option to generate a strong PSK and filter it through base64 encoding as shown.
In the following commands, 1 or 2 is the quality level and 10, 20, 40, and 70 are the character counts.
Generate PSK Key Using GPG Command
3. Using Pseudorandom Number Generators
You can also use any of the pseudorandom number generators in Linux such as /dev/random or /dev/urandom, as follows. The -c option of the head command helps to generate the number of characters.
4. Using date and sha245sum Commands
The date and sha256sum command can be combined to create a strong PSK as follows.
Generate PSK Using date Command
The above are some of the many ways of generating strong Pre-Shared Key in Linux. Do you know of any other methods? If yes, share it with us via the feedback form below.
-->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
Pre Shared Key Meaning
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.
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.
Next steps
Generate Pre Shared Key
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.