script snippet Script snippet to install OpenSSH server, configure it for key-based authentication, and add a public key for the specified user.

ssh_setup.sh

#!/bin/bash

# Update Ubuntu Packages
sudo apt update
sudo apt upgrade -y

# Install OpenSSH Server
sudo apt install openssh-server -y

# Start and Enable SSH Service
sudo systemctl start ssh
sudo systemctl enable ssh

# Configure SSH for Key-Based Authentication
sudo sed -i 's/#PubkeyAuthentication yes/PubkeyAuthentication yes/' /etc/ssh/sshd_config
sudo sed -i 's/#PasswordAuthentication yes/PasswordAuthentication no/' /etc/ssh/sshd_config
sudo sed -i 's/#AuthorizedKeysFile/AuthorizedKeysFile/' /etc/ssh/sshd_config
sudo systemctl restart ssh

# Allow SSH Through Firewall
sudo ufw allow ssh
sudo ufw enable

# Add Public Key to the Authorized Keys
USER_HOME=$(eval echo ~${SUDO_USER})
mkdir -p $USER_HOME/.ssh
chmod 700 $USER_HOME/.ssh

# Replace 'your_public_key_here' with your actual public key
echo "your_public_key_here" | tee -a $USER_HOME/.ssh/authorized_keys
chmod 600 $USER_HOME/.ssh/authorized_keys
chown -R $SUDO_USER:$SUDO_USER $USER_HOME/.ssh

# Print Completion Message
echo "OpenSSH installation and configuration completed successfully."