From 21ca6e61d122ae8774e477e41df55c1bfd4decb5 Mon Sep 17 00:00:00 2001
From: Krzysztof kuhy Rudnicki <krzysztofrudnicki0@gmail.com>
Date: Fri, 4 Jul 2025 13:27:56 +0200
Subject: [PATCH] feat: automatically restore etc hosts file on edit or remove

---
 scripts/setup_periodic_system.sh | 195 ++++++++++++++++++++++++++++++-
 1 file changed, 191 insertions(+), 4 deletions(-)

diff --git a/scripts/setup_periodic_system.sh b/scripts/setup_periodic_system.sh
index 1281a1e..22b5018 100755
--- a/scripts/setup_periodic_system.sh
+++ b/scripts/setup_periodic_system.sh
@@ -229,10 +229,168 @@ EOF
     echo "✓ Created startup service: $startup_service"
 }
 
+# Function to create hosts file monitor service
+create_hosts_monitor_service() {
+    echo ""
+    echo "6. Creating Hosts File Monitor Service..."
+    echo "========================================"
+    
+    local monitor_script="/usr/local/bin/hosts-file-monitor.sh"
+    local monitor_service="/etc/systemd/system/hosts-file-monitor.service"
+    
+    # Create the monitor script
+    cat > "$monitor_script" << EOF
+#!/bin/bash
+# Hosts file monitor script
+# Watches /etc/hosts for changes and restores it if needed
+# Created by setup_periodic_system.sh on $(date)
+
+LOG_FILE="/var/log/hosts-file-monitor.log"
+HOSTS_FILE="/etc/hosts"
+HOSTS_INSTALL_SCRIPT="$HOSTS_INSTALL_SCRIPT"
+
+# Function to log with timestamp
+log_message() {
+    echo "\$(date '+%Y-%m-%d %H:%M:%S') - \$1" >> "\$LOG_FILE"
+    echo "\$(date '+%Y-%m-%d %H:%M:%S') - \$1" >&2
+}
+
+# Function to check if hosts file needs restoration
+needs_restoration() {
+    # Check if file exists
+    if [[ ! -f "\$HOSTS_FILE" ]]; then
+        return 0  # File missing, needs restoration
+    fi
+    
+    # Check if file is empty or too small (less than 1000 lines indicates tampering)
+    local line_count=\$(wc -l < "\$HOSTS_FILE" 2>/dev/null || echo "0")
+    if [[ \$line_count -lt 1000 ]]; then
+        return 0  # File too small, likely tampered with
+    fi
+    
+    # Check if our custom entries are missing
+    if ! grep -q "Custom blocking entries" "\$HOSTS_FILE" 2>/dev/null; then
+        return 0  # Our custom entries missing, needs restoration
+    fi
+    
+    # Check if StevenBlack entries are missing
+    if ! grep -q "StevenBlack" "\$HOSTS_FILE" 2>/dev/null; then
+        return 0  # StevenBlack entries missing, needs restoration
+    fi
+    
+    return 1  # File seems intact
+}
+
+# Function to restore hosts file
+restore_hosts_file() {
+    log_message "Hosts file modification detected - initiating restoration"
+    
+    if [[ -f "\$HOSTS_INSTALL_SCRIPT" ]]; then
+        log_message "Running hosts installation script: \$HOSTS_INSTALL_SCRIPT"
+        
+        if bash "\$HOSTS_INSTALL_SCRIPT" >> "\$LOG_FILE" 2>&1; then
+            log_message "Hosts file restoration completed successfully"
+        else
+            log_message "Hosts file restoration failed with exit code \$?"
+        fi
+    else
+        log_message "ERROR: Hosts install script not found at \$HOSTS_INSTALL_SCRIPT"
+    fi
+}
+
+# Function to monitor with inotifywait
+monitor_with_inotify() {
+    log_message "Starting hosts file monitoring with inotify"
+    
+    # Monitor the hosts file and its directory for various events
+    inotifywait -m -e delete,move,modify,attrib,create --format '%w%f %e %T' --timefmt '%Y-%m-%d %H:%M:%S' "\$HOSTS_FILE" /etc/ 2>/dev/null | \
+    while read file event time; do
+        # Check if the event is related to our hosts file
+        if [[ "\$file" == "\$HOSTS_FILE" ]] || [[ "\$file" == "/etc/hosts" ]]; then
+            log_message "Event detected: \$event on \$file at \$time"
+            
+            # Small delay to avoid rapid-fire events
+            sleep 2
+            
+            # Check if restoration is needed
+            if needs_restoration; then
+                restore_hosts_file
+            else
+                log_message "Hosts file check passed - no restoration needed"
+            fi
+        fi
+    done
+}
+
+# Function to monitor with polling (fallback)
+monitor_with_polling() {
+    log_message "Starting hosts file monitoring with polling (fallback method)"
+    
+    while true; do
+        if needs_restoration; then
+            restore_hosts_file
+        fi
+        
+        # Check every 30 seconds
+        sleep 30
+    done
+}
+
+# Main execution
+log_message "=== Hosts File Monitor Started ==="
+
+# Check if inotify-tools is available
+if command -v inotifywait >/dev/null 2>&1; then
+    log_message "Using inotify for file monitoring"
+    monitor_with_inotify
+else
+    log_message "inotify-tools not available, using polling method"
+    log_message "Consider installing inotify-tools for better performance: pacman -S inotify-tools"
+    monitor_with_polling
+fi
+EOF
+
+    chmod +x "$monitor_script"
+    echo "✓ Created hosts monitor script: $monitor_script"
+    
+    # Create the systemd service
+    cat > "$monitor_service" << EOF
+[Unit]
+Description=Hosts File Monitor and Auto-Restore Service
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+User=root
+ExecStart=$monitor_script
+Restart=always
+RestartSec=10
+StandardOutput=journal
+StandardError=journal
+
+# Environment
+Environment=PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+
+# Security settings
+NoNewPrivileges=false
+PrivateTmp=true
+
+# Resource limits
+MemoryLimit=50M
+CPUQuota=10%
+
+[Install]
+WantedBy=multi-user.target
+EOF
+
+    echo "✓ Created hosts monitor service: $monitor_service"
+}
+
 # Function to enable and start services
 enable_services() {
     echo ""
-    echo "6. Enabling Services and Timer..."
+    echo "7. Enabling Services and Timer..."
     echo "================================="
     
     # Reload systemd daemon
@@ -248,11 +406,20 @@ enable_services() {
     systemctl enable periodic-system-startup.service
     echo "✓ Startup service enabled"
     
+    # Enable hosts file monitor service
+    systemctl enable hosts-file-monitor.service
+    systemctl start hosts-file-monitor.service
+    echo "✓ Hosts file monitor service enabled and started"
+    
     # Show timer status
     echo ""
     echo "Timer Status:"
     systemctl status periodic-system-maintenance.timer --no-pager -l
     
+    echo ""
+    echo "Hosts Monitor Status:"
+    systemctl status hosts-file-monitor.service --no-pager -l
+    
     echo ""
     echo "Next scheduled runs:"
     systemctl list-timers periodic-system-maintenance.timer --no-pager
@@ -261,7 +428,7 @@ enable_services() {
 # Function to create log rotation configuration
 create_log_rotation() {
     echo ""
-    echo "7. Setting up Log Rotation..."
+    echo "8. Setting up Log Rotation..."
     echo "============================="
     
     local logrotate_conf="/etc/logrotate.d/periodic-system-maintenance"
@@ -279,6 +446,19 @@ create_log_rotation() {
         systemctl reload-or-restart rsyslog > /dev/null 2>&1 || true
     endscript
 }
+
+/var/log/hosts-file-monitor.log {
+    weekly
+    rotate 4
+    compress
+    delaycompress
+    missingok
+    notifempty
+    create 644 root root
+    postrotate
+        systemctl reload-or-restart rsyslog > /dev/null 2>&1 || true
+    endscript
+}
 EOF
 
     echo "✓ Created log rotation configuration: $logrotate_conf"
@@ -287,7 +467,7 @@ EOF
 # Function to run initial execution
 run_initial_execution() {
     echo ""
-    echo "8. Running Initial Execution..."
+    echo "9. Running Initial Execution..."
     echo "==============================="
     
     echo "Would you like to run the system maintenance now to test the setup?"
@@ -309,6 +489,7 @@ create_execution_script
 create_systemd_service
 create_systemd_timer
 create_startup_service
+create_hosts_monitor_service
 enable_services
 create_log_rotation
 run_initial_execution
@@ -322,21 +503,27 @@ echo "✓ Execution script created: /usr/local/bin/periodic-system-maintenance.s
 echo "✓ Systemd service created and enabled: periodic-system-maintenance.service"
 echo "✓ Systemd timer created and enabled: periodic-system-maintenance.timer"
 echo "✓ Startup service created and enabled: periodic-system-startup.service"
+echo "✓ Hosts file monitor script and service created and enabled"
 echo "✓ Log rotation configured: /etc/logrotate.d/periodic-system-maintenance"
 echo ""
 echo "The system will now:"
 echo "• Run maintenance every hour"
 echo "• Run maintenance 5 minutes after system startup"
-echo "• Log all activities to /var/log/periodic-system-maintenance.log"
+echo "• Monitor hosts file for changes and restore if needed"
+echo "• Log all activities to /var/log/periodic-system-maintenance.log and /var/log/hosts-file-monitor.log"
 echo ""
 echo "To check status:"
 echo "  systemctl status periodic-system-maintenance.timer"
 echo "  systemctl list-timers periodic-system-maintenance.timer"
+echo "  systemctl status hosts-file-monitor.service"
 echo ""
 echo "To view logs:"
 echo "  tail -f /var/log/periodic-system-maintenance.log"
 echo "  journalctl -u periodic-system-maintenance.service -f"
+echo "  tail -f /var/log/hosts-file-monitor.log"
+echo "  journalctl -u hosts-file-monitor.service -f"
 echo ""
 echo "To disable (if needed):"
 echo "  sudo systemctl disable periodic-system-maintenance.timer"
 echo "  sudo systemctl disable periodic-system-startup.service"
+echo "  sudo systemctl disable hosts-file-monitor.service"