# Security & Performance Improvements

## ✅ Implemented Security Features

### 1. Bot & Crawler Blocking
- **`.htaccess`**: Blocks common search engine bots (Googlebot, Bingbot, etc.)
- **`robots.txt`**: Explicitly disallows all crawlers
- **PHP-level detection**: Blocks bots at application level in `index.php` and `api.php`
- **User-Agent validation**: Blocks empty or suspicious user agents

### 2. Security Headers
- **X-Frame-Options**: Prevents clickjacking attacks
- **X-Content-Type-Options**: Prevents MIME type sniffing
- **X-XSS-Protection**: Enables browser XSS protection
- **Referrer-Policy**: Controls referrer information
- **Content-Security-Policy**: Restricts resource loading
- **Server information hiding**: Removes X-Powered-By header

### 3. Rate Limiting
- **Login rate limiting**: Max 5 attempts per 15 minutes per IP/username
- **API rate limiting**: Max 100 requests per minute per IP
- **Automatic lockout**: Temporary ban after exceeding limits
- **Login attempts tracking**: Database table tracks all attempts

### 4. CSRF Protection
- **CSRF tokens**: Required for all state-changing operations
- **Token validation**: Server-side validation using hash_equals()
- **Session-based tokens**: Unique token per session

### 5. Input Validation & Sanitization
- **Input length limits**: Prevents buffer overflow attacks
- **SQL injection prevention**: All queries use prepared statements
- **XSS prevention**: htmlspecialchars() on all output
- **Type validation**: Strict type checking for numeric inputs

### 6. Session Security
- **HttpOnly cookies**: Prevents JavaScript access to session cookies
- **Secure cookies**: Enabled when HTTPS is available
- **SameSite cookies**: Prevents CSRF via cookie-based attacks
- **Session regeneration**: New session ID on login

## ✅ Performance Optimizations

### 1. Database Indexes
Run `optimize_database.php` to create indexes on:
- **jobs table**: job_id, branch, date, status, model, phone, customer, invoice_id, is_deleted
- **stock_list table**: type, category, part_name, supplier
- **customers table**: phone, name
- **activity_logs table**: user, action, created_at
- **login_attempts table**: username, ip_address, attempt_time
- **expenses table**: branch, date

### 2. Query Optimization
- **LIMIT clauses**: Added to prevent loading excessive data
- **Indexed columns**: Queries use indexed columns for faster lookups
- **Prepared statements**: Reusable query plans
- **Batch operations**: Reduced database round trips

### 3. Caching
- **Permission caching**: Permissions cached in session to reduce DB queries
- **Browser caching**: Static assets cached via .htaccess

### 4. Compression
- **Gzip compression**: Enabled for text files (CSS, JS, HTML)
- **Image optimization**: Long-term caching for images

## 📋 Files Created/Modified

### New Files:
1. **`.htaccess`** - Apache security and performance configuration
2. **`robots.txt`** - Blocks all search engine crawlers
3. **`optimize_database.php`** - Database index creation script
4. **`SECURITY_IMPROVEMENTS.md`** - This documentation

### Modified Files:
1. **`index.php`** - Added bot detection, rate limiting, security headers
2. **`api.php`** - Added bot detection, rate limiting, CSRF protection, security headers
3. **`dashboard.php`** - Added security headers

## 🚀 How to Apply

### Step 1: Run Database Optimization
1. Login to the system as Master/Endie
2. Navigate to: `http://yoursite.com/my_pos/optimize_database.php`
3. The script will create all necessary indexes
4. This only needs to be run once

### Step 2: Verify .htaccess
- The `.htaccess` file is automatically active if Apache has mod_rewrite enabled
- Check that file permissions allow Apache to read it

### Step 3: Test Security
- Try accessing the site with a bot user-agent (should be blocked)
- Check browser console for security headers
- Test rate limiting by making rapid API calls

## 🔒 Security Best Practices

1. **Keep PHP Updated**: Regularly update PHP to latest stable version
2. **Database Backups**: Regular backups via `backup.php` or `sync_to_backup.php`
3. **Strong Passwords**: Enforce strong passwords for all users
4. **HTTPS**: Use HTTPS in production (SSL certificate required)
5. **Monitor Logs**: Check `activity_logs` and `login_attempts` regularly
6. **Access Control**: Review user permissions regularly

## 📊 Performance Monitoring

### Check Query Performance:
```sql
-- Check slow queries
SHOW FULL PROCESSLIST;

-- Analyze table indexes
SHOW INDEX FROM jobs;
SHOW INDEX FROM stock_list;
```

### Monitor Rate Limiting:
- Check `login_attempts` table for failed login patterns
- Review API rate limit session data

## ⚠️ Important Notes

1. **.htaccess requires mod_rewrite**: Ensure Apache has mod_rewrite enabled
2. **Bot blocking is aggressive**: Legitimate API clients must have proper user-agent
3. **Rate limits are per-session**: Clearing cookies resets API rate limits
4. **Indexes take space**: Database will use slightly more disk space after optimization

## 🔄 Maintenance

- **Monthly**: Review login_attempts table for suspicious activity
- **Quarterly**: Run `optimize_database.php` again to ensure all indexes exist
- **As needed**: Update blocked bot list in .htaccess if new threats emerge
