Install OpenSSH on your Desktop

To install and configure OpenSSH on a KDE Plasma system, you’ll typically use your distribution’s package manager. Once installed, you can then configure the server and client settings.

Installation:

1. 1. Using your distribution’s package manager:
   • For Ubuntu and Debian-based systems: sudo apt install openssh-server openssh-client
   • For Fedora and Red Hat-based systems: sudo dnf install openssh openssh-server
   • For Arch Linux and derivatives: sudo pacman -S openssh
2. 2. Enable and start the SSH service:
   • sudo systemctl enable --now sshd
   • This command ensures the SSH service starts automatically on boot. 

Configuration:

1. 1. OpenSSH Server Configuration:
   • The main configuration file for the OpenSSH server is /etc/ssh/sshd_config. 
   • You can edit this file using a text editor with root privileges.
   • Important: Before making changes, it’s a good idea to back up the original configuration: sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.bak 
   • Common configuration options include:
     • Port: The port SSH listens on (default is 22).
     • PermitRootLogin: Controls whether root users can log in via SSH (generally recommended to disable).
     • PasswordAuthentication: Controls whether password-based authentication is allowed (using SSH keys is more secure).
     • PubkeyAuthentication: Controls whether public key authentication is enabled.
     • StrictModes: Controls how file permissions are enforced (recommended to be enabled).
   • After making changes, restart the SSH service: sudo systemctl restart sshd 
2. 2. OpenSSH Client Configuration:
   • If you’re using Konsole, you can configure it to use the SSH Manager plugin for managing connections. 
   • You can also configure SSH settings within Konsole’s preferences.
   • For general SSH client configuration, you can use the ssh_config file located in your home directory (~/.ssh/config). 

Key Management:

1. 1. Generating SSH keys:
   • ssh-keygen -t rsa
   • This command generates a public and private key pair.
   • You can optionally add a passphrase to your private key for added security.
2. 2. Distributing public keys:
   • ssh-copy-id user@hostname
   • This command copies your public key to the ~/.ssh/authorized_keys file on the remote server. 

Additional Tips:

• Consider using a firewall (like ufw on Ubuntu) to restrict SSH access to only necessary IP addresses. 
• If you’re using KWallet to store your SSH passphrase, you can configure it to automatically unlock on login. 
• For connecting to an SSH proxy, you can use the sshuttle command-line utility or configure a proxy in your browser. 
• KDE Plasma offers various tools for managing network connections, including SSH connections, through the Network Manager.