Actualiser miscellaneous/secure_ssh.sh
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#!/bin/bash
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# This script configures SSH server security settings following Mozilla's guidelines
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# It allows choosing between SSH key and password authentication methods
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# Reference: https://infosec.mozilla.org/guidelines/openssh
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# Warning: Before running this script, make sure you have created a user and an SSH key in the authorized_keys file.
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# This script is designed to configure the SSH server on a Linux system according to Mozilla's security best practices.
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# It enhances the security of SSH connections by enforcing modern encryption standards, disabling insecure protocols, and restricting root access.
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# The script backs up the original SSH configuration file, applies a new set of secure settings, and then restarts the SSH service to apply the changes.
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# These settings include disabling password authentication, limiting access to strong ciphers and key exchange methods, and enhancing brute-force protection.
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# These recommendations are based on Mozilla's guidelines, which can be found here: https://infosec.mozilla.org/guidelines/openssh
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# Usage:
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# 1. Save this script as "secure_ssh.sh"
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# 2. Make it executable: chmod +x secure_ssh.sh
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# 3. Run with root privileges: sudo ./secure_ssh.sh
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# 4. Follow the interactive prompts to configure your SSH security settings
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# To run this script, save it as "secure_ssh.sh" and make it executable by running the command: `chmod +x secure_ssh.sh`.
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# After that, execute it with root privileges using: `sudo ./secure_ssh.sh`.
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# The script will automatically apply the recommended configuration changes and restart the SSH service.
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# Check if the script is run as root
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if [[ "$EUID" -ne 0 ]]; then
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@@ -16,171 +19,83 @@ if [[ "$EUID" -ne 0 ]]; then
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exit 1
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fi
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# Define important variables
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# Variables
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SSHD_CONFIG="/etc/ssh/sshd_config"
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BACKUP_FILE="${SSHD_CONFIG}_$(date +'%Y%m%d_%H%M%S').bak"
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BACKUP_FILE="${SSHD_CONFIG}_$(date +'%Y%m%d_%H%M%S').bak" # Backup with date and time
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# Function to validate IP address
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validate_ip() {
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local ip=$1
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local stat=1
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if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
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OIFS=$IFS
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IFS='.'
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ip=($ip)
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IFS=$OIFS
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[[ ${ip[0]} -le 255 && ${ip[1]} -le 255 && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
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stat=$?
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fi
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return $stat
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}
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# Create a backup of the current SSH configuration
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# Backup the old configuration with a timestamp
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cp "$SSHD_CONFIG" "$BACKUP_FILE"
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echo "Current SSH configuration backed up to $BACKUP_FILE"
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# Configure SSH port (mandatory)
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while true; do
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read -p "Enter the SSH port to use (between 1024 and 65535): " new_port
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if [[ "$new_port" =~ ^[0-9]+$ ]] && [ "$new_port" -ge 1024 ] && [ "$new_port" -le 65535 ]; then
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port_setting="Port $new_port"
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break
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else
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echo "Error: Please enter a valid port number between 1024 and 65535"
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fi
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done
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# Ask user if they want to restrict SSH access to a single IP
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read -p "Do you want to restrict SSH access to a single IP? (yes/no): " restrict_ip
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# Configure IP whitelist (mandatory)
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while true; do
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read -p "Enter the IP address to whitelist for SSH access (e.g., 192.168.1.100): " allowed_ip
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if validate_ip "$allowed_ip"; then
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if [[ "$restrict_ip" == "yes" ]]; then
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read -p "Enter the IP address to allow SSH access: " allowed_ip
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allow_users="AllowUsers *@${allowed_ip}"
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break
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else
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echo "Error: Please enter a valid IP address"
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allow_users="# AllowUsers configuration not set"
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fi
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done
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# Present authentication method options to the user
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echo "Choose authentication method:"
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echo "1) SSH key only (more secure)"
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echo "2) Password authentication"
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read -p "Enter your choice (1 or 2): " auth_choice
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# Handle authentication method selection
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case $auth_choice in
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1)
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# Configure SSH key authentication
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auth_method="PasswordAuthentication no"
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echo "SSH key authentication selected"
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# Check for existing SSH key configuration
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if [ ! -f "/root/.ssh/authorized_keys" ]; then
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read -p "No SSH key found. Would you like to add one now? (yes/no): " add_key
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if [[ "$add_key" == "yes" ]]; then
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# Create SSH directory with proper permissions
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mkdir -p /root/.ssh
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read -p "Paste your public SSH key: " ssh_key
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echo "$ssh_key" >> /root/.ssh/authorized_keys
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# Set proper permissions for SSH files
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chmod 700 /root/.ssh
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chmod 600 /root/.ssh/authorized_keys
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# Ask user if they want to change the SSH port
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read -p "Do you want to change the SSH port? (yes/no): " change_port
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if [[ "$change_port" == "yes" ]]; then
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read -p "Enter the new SSH port: " new_port
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port_setting="Port $new_port"
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else
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echo "Warning: No SSH key configured. You might be locked out!"
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exit 1
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port_setting="# Port configuration not changed"
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fi
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fi
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;;
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2)
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# Configure password authentication
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auth_method="PasswordAuthentication yes"
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echo "Password authentication selected"
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;;
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*)
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echo "Invalid choice. Exiting."
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exit 1
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;;
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esac
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# Create new SSH configuration file with secure settings
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# Ask user if they want to use password or key-based authentication
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read -p "Do you want to use password or key-based authentication? (password/key): " auth_method
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if [[ "$auth_method" == "password" ]]; then
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password_auth="PasswordAuthentication yes"
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key_auth="# PasswordAuthentication no"
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else
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password_auth="# PasswordAuthentication no"
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key_auth="PubkeyAuthentication yes"
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fi
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# Modify the sshd_config file
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cat <<EOL > "$SSHD_CONFIG"
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# SSH Server Configuration
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# Generated by secure_ssh.sh script
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# Based on Mozilla's Modern OpenSSH server configuration
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# Last modified: $(date)
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# Protocol version (only SSH protocol 2 is secure)
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# Mozilla SSH Security Recommendations
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Protocol 2
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# Port configuration (mandatory)
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$port_setting
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# IP restriction settings (mandatory)
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$allow_users
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# Authentication configuration
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$auth_method
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# Cryptographic settings
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# Only modern, secure ciphers are enabled
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# Enable only secure ciphers
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Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
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# Key exchange algorithms
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# Enable only secure key exchange algorithms
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KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256
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# Message Authentication Codes (MACs)
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# Enable only secure MAC algorithms
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MACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha2-512
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# Host keys
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# Authentication method based on user input
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$password_auth
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$key_auth
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# Disable old host keys
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HostKey /etc/ssh/ssh_host_ed25519_key
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HostKey /etc/ssh/ssh_host_rsa_key
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# Access control settings
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# Restrict root access
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PermitRootLogin no
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# Strict connection policy
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MaxAuthTries 3
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LoginGraceTime 30
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# Additional security measures
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# Additional security recommendations
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AllowTcpForwarding no
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MaxSessions 2
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LogLevel VERBOSE
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ClientAliveInterval 300
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ClientAliveCountMax 2
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# IP restriction based on user input
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$allow_users
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# SSH port based on user input
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$port_setting
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EOL
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# Configure UFW firewall if installed
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if command -v ufw >/dev/null 2>&1; then
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echo "Configuring UFW firewall..."
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ufw allow from "$allowed_ip" to any port "$new_port" proto tcp
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ufw status
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fi
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# Restart SSH service to apply new configuration
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# Restart the SSH service
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systemctl restart sshd
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# Display completion message and configuration summary
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echo "
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SSH Configuration Summary:
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-------------------------
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Port: $new_port
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Whitelisted IP: $allowed_ip
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Authentication Method: ${auth_choice == 1 ? 'SSH Key' : 'Password'}
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Backup File: $BACKUP_FILE
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Important notes:
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1. Keep your backup file safe
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2. Test your new SSH configuration in a new session before logging out
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3. If you get locked out, use the backup file to restore the previous configuration
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4. The following command will be needed to connect:
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ssh -p $new_port user@server_ip
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Next steps:
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1. Open a new terminal
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2. Try to connect using the new configuration
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3. Do NOT close this session until you confirm the new configuration works
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"
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if [[ "$auth_choice" == "1" ]]; then
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echo "WARNING: Make sure you have a valid SSH key configured before logging out!"
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fi
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echo "SSH configuration has been updated and backed up to $BACKUP_FILE according to Mozilla's security recommendations."
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