Firewall Logging and Monitoring

Firewall Logging and Monitoring

Comprehensive firewall logging enables security monitoring, troubleshooting, and compliance requirements. However, excessive logging impacts performance and generates overwhelming data volumes. Implement strategic logging capturing security-relevant events while maintaining manageable log volumes and system performance.

Configure Windows Firewall logging through Advanced Security settings or PowerShell:

Set-NetFirewallProfile -Profile Domain,Private,Public -LogBlocked True -LogAllowed True -LogFileName %SystemRoot%\System32\LogFiles\Firewall\pfirewall.log -LogMaxSizeKilobytes 32768

Parse Windows Firewall logs using PowerShell for analysis: Get-Content C:\Windows\System32\LogFiles\Firewall\pfirewall.log | Select-String "DROP". Forward logs to SIEM systems using Windows Event Forwarding or third-party agents.

Linux firewall logging uses kernel logging facilities. Configure iptables logging for specific rules: iptables -A INPUT -j LOG --log-prefix "FIREWALL:DROP:" --log-level 4. Direct firewall logs to separate files via rsyslog configuration:

:msg,contains,"FIREWALL:" /var/log/firewall.log
& stop

Implement log rotation to manage file sizes. Use fail2ban to automatically respond to repeated failed connection attempts detected in firewall logs.

Establish firewall monitoring baselines identifying normal traffic patterns. Alert on deviations indicating potential security incidents. Key metrics include connection rates, blocked traffic spikes, and unusual port access attempts. Correlate firewall logs with other security data for comprehensive threat detection. Regular log analysis identifies misconfigurations and optimization opportunities.