Detection Engine Configuration Guide

This guide provides comprehensive documentation for configuring the FastAPI Guard Detection Engine to optimize security and performance for your specific needs.

Configuration Overview

The Detection Engine is configured through the SecurityConfig model, which provides numerous parameters to control detection behavior, performance characteristics, and integration options.

Configuration Categories

1. Core Detection Settings

These settings control the fundamental behavior of the detection engine:

from guard import SecurityConfig

config = SecurityConfig(
    # Enable/disable penetration detection
    enable_penetration_detection=True,  # Default: True

    # Auto-ban settings for suspicious activity
    auto_ban_threshold=5,        # Ban after N suspicious requests
    auto_ban_duration=3600,      # Ban duration in seconds (1 hour)
)

2. Detection Engine Settings

Fine-tune the detection engine components:

config = SecurityConfig(
    # Pattern compilation and execution
    detection_compiler_timeout=2.0,      # Timeout for pattern matching (seconds)

    # Content preprocessing
    detection_max_content_length=10000,  # Max characters to analyze
    detection_preserve_attack_patterns=True,  # Preserve attacks during truncation

    # Semantic analysis
    detection_semantic_threshold=0.7,    # Threat score threshold (0.0-1.0)
)

3. Performance Monitoring Settings

Configure performance tracking and optimization:

config = SecurityConfig(
    # Anomaly detection
    detection_anomaly_threshold=3.0,     # Standard deviations for anomaly

    # Pattern performance
    detection_slow_pattern_threshold=0.1,  # Slow pattern threshold (seconds)

    # Monitoring history
    detection_monitor_history_size=1000,   # Number of metrics to keep
    detection_max_tracked_patterns=1000,   # Maximum patterns to track
)

Complete Configuration Example

Here's a comprehensive configuration example with all detection engine settings:

from fastapi import FastAPI
from guard import SecurityMiddleware, SecurityConfig

app = FastAPI()

# Full detection engine configuration
config = SecurityConfig(
    # Core security settings
    enable_penetration_detection=True,
    auto_ban_threshold=5,
    auto_ban_duration=3600,
    passive_mode=False,  # Set to True for monitoring without blocking

    # Detection engine optimization
    detection_compiler_timeout=2.0,
    detection_max_content_length=10000,
    detection_preserve_attack_patterns=True,
    detection_semantic_threshold=0.7,

    # Performance monitoring
    detection_anomaly_threshold=3.0,
    detection_slow_pattern_threshold=0.1,
    detection_monitor_history_size=1000,
    detection_max_tracked_patterns=1000,

    # Redis integration (optional)
    use_redis=True,
    redis_host="localhost",
    redis_port=6379,
    redis_db=0,

    # Agent integration (optional)
    enable_agent=True,
    agent_api_key="your-api-key",
    agent_enable_events=True,
    agent_enable_metrics=True,

    # Logging
    custom_log_file="security.log",
    log_level="WARNING"
)

app.add_middleware(SecurityMiddleware, config=config)

Configuration Profiles

High Security Profile

For applications requiring maximum security with stricter detection:

high_security_config = SecurityConfig(
    # Strict detection settings
    enable_penetration_detection=True,
    auto_ban_threshold=3,            # Lower threshold
    auto_ban_duration=7200,          # Longer ban (2 hours)

    # Tighter detection parameters
    detection_compiler_timeout=1.0,   # Shorter timeout
    detection_max_content_length=5000,  # Analyze less content
    detection_semantic_threshold=0.5,   # More sensitive detection

    # Aggressive monitoring
    detection_anomaly_threshold=2.0,    # More sensitive to anomalies
    detection_slow_pattern_threshold=0.05,  # Stricter performance
)

Performance Optimized Profile

For high-traffic applications prioritizing performance:

performance_config = SecurityConfig(
    # Balanced detection
    enable_penetration_detection=True,
    auto_ban_threshold=10,           # Higher threshold
    auto_ban_duration=1800,          # Shorter ban (30 minutes)

    # Performance-focused settings
    detection_compiler_timeout=3.0,   # Longer timeout allowed
    detection_max_content_length=2000,  # Analyze less content
    detection_semantic_threshold=0.8,   # Less sensitive

    # Relaxed monitoring
    detection_anomaly_threshold=4.0,    # Less sensitive
    detection_slow_pattern_threshold=0.2,  # More tolerant
    detection_monitor_history_size=500,    # Smaller history
)

Development Profile

For development and testing environments:

dev_config = SecurityConfig(
    # Enable detection but in passive mode
    enable_penetration_detection=True,
    passive_mode=True,               # Log but don't block

    # Verbose settings for debugging
    detection_compiler_timeout=5.0,   # Generous timeout
    detection_max_content_length=50000,  # Large content analysis

    # Full monitoring
    detection_monitor_history_size=5000,  # Large history

    # Detailed logging
    log_level="DEBUG",
    custom_log_file="security-debug.log"
)

Parameter Reference

Detection Compiler Settings

Parameter	Type	Default	Range	Description
detection_compiler_timeout	float	2.0	0.1-30.0	Maximum seconds for pattern execution

Usage Guidelines:

• Lower values (0.1-1.0): High security, may timeout complex patterns
• Default (2.0): Balanced for most applications
• Higher values (3.0-5.0): More tolerant, for complex legitimate patterns

Content Preprocessing Settings

Parameter	Type	Default	Description
detection_max_content_length	int	10000	Maximum characters to process
detection_preserve_attack_patterns	bool	True	Preserve attacks during truncation

Best Practices: - Set max_content_length based on your typical request size - Always keep preserve_attack_patterns True for security - Consider memory usage with very large content limits

Semantic Analysis Settings

Parameter	Type	Default	Range	Description
detection_semantic_threshold	float	0.7	0.0-1.0	Minimum score to consider threat

Threshold Guidelines: - 0.0-0.3: Very sensitive, many false positives - 0.4-0.6: Sensitive, catches more attacks - 0.7-0.8: Balanced (recommended) - 0.9-1.0: Very strict, may miss obfuscated attacks

Performance Monitoring Settings

Parameter	Type	Default	Description
detection_anomaly_threshold	float	3.0	Standard deviations for anomaly
detection_slow_pattern_threshold	float	0.1	Seconds to consider pattern slow
detection_monitor_history_size	int	1000	Metrics to keep in memory
detection_max_tracked_patterns	int	1000	Maximum patterns to track

Optimization Tips: - Lower anomaly_threshold to catch unusual behavior earlier - Adjust slow_pattern_threshold based on your performance requirements - Increase history sizes for better long-term analysis

Dynamic Configuration

You can adjust certain settings at runtime:

from guard.handlers.suspatterns_handler import sus_patterns_handler

# Adjust semantic threshold dynamically
await sus_patterns_handler.configure_semantic_threshold(0.8)

# Add custom patterns
await sus_patterns_handler.add_pattern(
    r"(?i)custom_threat_pattern",
    custom=True
)

# Check component status
status = await sus_patterns_handler.get_component_status()
print(f"Components active: {status}")

Configuration Validation

The Detection Engine validates configuration on startup:

try:
    config = SecurityConfig(
        detection_compiler_timeout=0.05  # Too low, will be adjusted
    )
except ValueError as e:
    print(f"Configuration error: {e}")

Environment Variables

You can also configure the detection engine using environment variables:

# Core settings
FASTAPI_GUARD_ENABLE_PENETRATION_DETECTION=true
FASTAPI_GUARD_AUTO_BAN_THRESHOLD=5

# Detection engine
FASTAPI_GUARD_DETECTION_COMPILER_TIMEOUT=2.0
FASTAPI_GUARD_DETECTION_MAX_CONTENT_LENGTH=10000
FASTAPI_GUARD_DETECTION_SEMANTIC_THRESHOLD=0.7

# Performance monitoring
FASTAPI_GUARD_DETECTION_ANOMALY_THRESHOLD=3.0
FASTAPI_GUARD_DETECTION_SLOW_PATTERN_THRESHOLD=0.1

Monitoring Configuration Effectiveness

Check Performance Impact

# Get performance statistics
stats = await sus_patterns_handler.get_performance_stats()

# Analyze configuration effectiveness
if stats['summary']['average_time'] > 0.05:
    print("Consider optimizing configuration for better performance")

if stats['summary']['timeout_rate'] > 0.01:
    print("High timeout rate - consider increasing compiler_timeout")

Monitor False Positives

# Track false positive rate
if config.passive_mode:
    # In passive mode, analyze logs for false positives
    # Adjust detection_semantic_threshold based on findings
    pass

Configuration Checklist

Before deploying to production:

• [ ] Test configuration in staging environment
• [ ] Verify timeout settings don't impact legitimate traffic
• [ ] Confirm content length limits handle your use cases
• [ ] Test semantic threshold with known attack patterns
• [ ] Monitor performance metrics for first 24 hours
• [ ] Review logs for false positives/negatives
• [ ] Ensure Redis/Agent connections are stable
• [ ] Document any custom patterns added

Troubleshooting

High False Positive Rate

# Increase semantic threshold
config.detection_semantic_threshold = 0.8

# Review problematic patterns
stats = await sus_patterns_handler.get_performance_stats()
for pattern in stats['problematic_patterns']:
    print(f"Review pattern: {pattern}")

Performance Issues

# Reduce content analysis size
config.detection_max_content_length = 5000

# Increase timeout tolerance
config.detection_compiler_timeout = 3.0

# Monitor specific patterns
slow_patterns = monitor.get_slow_patterns(threshold=0.05)

Memory Usage

# Reduce monitoring history
config.detection_monitor_history_size = 500
config.detection_max_tracked_patterns = 500

# Clear old metrics periodically
monitor.clear_old_metrics()

Next Steps

• Review Performance Tuning Guide
• Explore Custom Pattern Development
• Monitor with Security Dashboard