SSH Keygen for Password-less Server Login

Using SSH keys for authentication is a secure and convenient way to log into a remote server without needing to enter a password every time. Below are the steps to set up password-less SSH login using RSA keys.

Step 1: Generate an SSH Key Pair

First, generate an SSH key pair on your local machine. This command will create a public-private key pair.

ssh-keygen -t rsa -b 2048

You'll be prompted to specify a location to save the key and optionally enter a passphrase. If you choose to enter a passphrase, you'll add an extra layer of security, but you'll need to enter the passphrase each time you use the key.

Step 2: Copy the Public Key to the Server

Use the ssh-copy-id command to copy your public key to the remote server. Replace user with your username and server with the remote server's address.

ssh-copy-id user@server

You'll be prompted to enter the remote user's password. This is the last time you should need to use the password to log in to the server.

Step 3: Log into the Server

Now, you can log into the remote server without being prompted for a password.

ssh user@server

Using a Custom Port

If your SSH server listens on a port other than the default port (22), you can specify the custom port using the -p option.

ssh-copy-id -p 8129 user@host

Note: When specifying a custom port, the port number must be placed before the user@host portion of the command.

References

• SSH Copy-ID Documentation
• Using SSH-Copy-ID on a Different Port
• Source for Custom Port Usage

By following these steps, you can set up password-less SSH login, which enhances security and convenience for accessing your remote servers.