Windows OpenSSH Rejects Key: Default Shell Set Registry

Setting up OpenSSH Server on Windows Server 2022 with Key-based Authentication

In this article, we will discuss how to set up an OpenSSH server on a Windows Server 2022 machine and configure key-based authentication. By default, OpenSSH uses command-line arguments to specify the default shell for users. However, we can change this behavior by setting the default shell using the registry.

Prerequisites

Before we begin, make sure that you have the following:

• A Windows Server 2022 machine
• OpenSSH server installed and running on the machine
• A user account with administrative privileges

Setting up Key-based Authentication

Key-based authentication is a more secure way of logging in to your server than using passwords. It involves generating a pair of keys (public and private) on your local machine and copying the public key to the server. Here are the steps to set up key-based authentication:

1. Generate a pair of keys on your local machine using the following command:

This will generate two files: id_rsa (private key) and id_rsa.pub (public key).

2. Copy the public key to the server using the following command:

Replace myuser with your username and server.tld with your server's domain name or IP address.

3. Test the key-based authentication by logging in to the server using the following command:

You should be able to log in without any prompts for a password.

Setting the Default Shell using the Registry

By default, OpenSSH uses the command prompt as the default shell for users. However, we can change this behavior by setting the default shell using the registry. Here are the steps to set the default shell:

1. Press Win + R to open the Run dialog box.
2. Type regedit and press Enter to open the Registry Editor.
3. Navigate to the following key:

4. Right-click on the right pane and select New > String Value.
5. Name the new value DefaultShell and set its value to the path of the default shell executable, for example:

This will set PowerShell as the default shell for users.

In this article, we have discussed how to set up an OpenSSH server on a Windows Server 2022 machine and configure key-based authentication. We have also shown how to set the default shell using the registry. By following these steps, you can ensure secure and easy access to your Windows Server 2022 machine using OpenSSH.

References

• Install and Configure OpenSSH on Windows Server
• SSH Key Management for OpenSSH on Windows Server
• Use Schannel for SSH Authentication on Windows Server