Performance Metrics and Optimization

Performance Metrics and Optimization

Monitoring firewall performance ensures security controls don't degrade web server responsiveness. Track key performance indicators that reveal both security effectiveness and operational health.

Essential performance metrics include:

  • Processing Latency: Time added by firewall inspection
  • Throughput: Bandwidth capacity and utilization
  • Connection Table Utilization: Percentage of maximum connections used
  • Rule Processing Time: Time spent evaluating each rule
  • Drop Rate: Percentage of packets dropped due to rules vs. performance

Implement performance monitoring alongside security monitoring:

import psutil
import time

class FirewallPerformanceMonitor:
    def __init__(self):
        self.metrics = {
            'cpu_usage': [],
            'memory_usage': [],
            'packet_rate': [],
            'connection_count': [],
            'rule_processing_time': []
        }
        
    def collect_metrics(self):
        # System metrics
        self.metrics['cpu_usage'].append(psutil.cpu_percent(interval=1))
        self.metrics['memory_usage'].append(psutil.virtual_memory().percent)
        
        # Firewall-specific metrics
        connection_count = self.get_connection_count()
        self.metrics['connection_count'].append(connection_count)
        
        # Calculate moving averages
        if len(self.metrics['cpu_usage']) > 60:  # Keep last hour
            self.metrics['cpu_usage'].pop(0)
            
        return {
            'avg_cpu': sum(self.metrics['cpu_usage']) / len(self.metrics['cpu_usage']),
            'current_connections': connection_count,
            'memory_pressure': self.metrics['memory_usage'][-1] > 80
        }
    
    def get_connection_count(self):
        # Platform-specific connection counting
        try:
            # Linux netfilter
            with open('/proc/sys/net/netfilter/nf_conntrack_count', 'r') as f:
                return int(f.read().strip())
        except:
            # Fallback to netstat parsing
            connections = os.popen('netstat -an | grep ESTABLISHED | wc -l').read()
            return int(connections.strip())