Firewall Periodic Review and Monitoring Configuration Guidelines

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Introduction This Knowledge Base (KB) document defines a standardized approach for performing periodic reviews of firewall configurations related to monitoring, logging, and alerting. The objective is to ensure that security policies, NAT rules, log forwarding, and associated configurations are actively required, correctly implemented, and properly documented.

Over time, firewall environments tend to accumulate temporary rules, test integrations, and legacy monitoring configurations. If these are not reviewed periodically, they can result in performance degradation, excessive logging, log loops, and reduced operational visibility. This KB establishes a structured checklist to help network teams perform consistent and effective periodic configuration reviews.

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Security Policy Review

  • Perform automated analysis using tools such as ManageEngine Firewall Analyzer to identify:
    • Unused or suppressed rules
    • Rules with no hit count for extended periods
    • Redundant objects or shadowed rules
  • Conduct a manual review of all security policies to validate business relevance
  • Identify and remove unused, temporary, or test rules
  • Validate source, destination, service, and application scope for each rule
  • Prefer the use of named address and service objects instead of hardcoded IP addresses or ports
  • Verify logging configuration is enabled or disabled per rule based on operational requirements
  • Ensure firewall management access rules have logging disabled to prevent log loops

NAT Policy Review

  • Review all Source NAT and Destination NAT rules
  • Identify stale, unused, or temporary NAT entries
  • Validate NAT rules created specifically for monitoring, logging, or reporting servers
  • Confirm NAT rules align with the current network architecture
  • Remove NAT rules created for completed or abandoned testing activities
  • Verify NAT functionality from public IP addresses where applicable
  • If NAT access is not required from all public IPs, restrict access using source IP filtering at the NAT rule or corresponding security policy level

Syslog Forwarding Review

  • List all configured Syslog destinations
  • Capture and document destination name, IP address, port, and protocol
  • Validate the business requirement for each Syslog destination
  • Confirm ownership and operational responsibility for each log receiver
  • Remove Syslog forwarding for decommissioned or test servers
  • Ensure only approved SOC and reporting systems receive firewall logs

SNMP Configuration Review

  • Review all SNMP trap destinations configured on the firewall
  • Validate whether SNMP traps are actively consumed by monitoring tools
  • Confirm SNMP usage purpose, such as integration with:
    • Log360
    • OpManager
    • OpenNMS
  • Remove SNMP forwarding where there is no active operational requirement
  • Validate SNMP version, community strings, and access scope (Read or Write)

NetFlow Configuration Review

  • Review all NetFlow exporters configured on the firewall
  • Identify destination IP addresses and listening ports
  • Validate the analysis or reporting requirement for each NetFlow receiver
  • Remove NetFlow forwarding for test or unused collectors
  • Confirm NetFlow usage aligns with active tickets, monitoring objectives, or reporting needs

Documentation and Ownership Tracking

  • Maintain a single consolidated document for Syslog, SNMP, and NetFlow forwarding
  • Record the following details for each integration:
    • Destination
    • Purpose
    • Owner
    • Related ticket or change request number
  • Ensure all configuration changes are documented immediately
  • Ensure test configurations have defined timelines and exit criteria

Monitoring Tool Configuration Review

  • Verify that the monitoring tool is able to monitor the firewall using SNMP, including SNMP traps where supported
  • Record baseline performance metrics for future reference:
    • CPU utilization
    • Memory utilization
    • Session count

Email Alert Configuration Review

  • Review firewall email server profiles
  • Validate SMTP relay configuration and authentication credentials
  • Confirm alert recipient distribution lists
  • Remove personal or inactive email addresses
  • Validate alert severity thresholds and notification rules
  • Test email alert functionality, if supported by the platform

Log Loop Prevention Validation

  • Verify firewall-to-log-server security policies
  • Ensure logging is disabled for traffic used to forward logs
  • Confirm log forwarding traffic is not logged or forwarded again
  • Validate address objects for log servers are correctly defined and referenced

Review Frequency and Triggers

  • Perform this review on a quarterly basis
  • Mandatory review after adding new monitoring or logging integrations
  • Mandatory review when abnormal firewall session counts are observed
  • Mandatory review during SOC incidents or performance degradation events

Other Configuration Review

  • Verify ISP configurations and load-balancing behavior
  • Confirm each ISP link is operational and failover alerts are generated correctly
  • Verify the firewall can reach the Internet for:
    • Signature updates
    • Firmware updates
    • License validation
  • Verify DNS, DHCP, and NTP configurations are correct
  • Validate LAN interfaces and zone assignments
  • Verify firewall firmware is up to date and free from known bugs or security issues
  • Ensure management access is not enabled on Internet-facing interfaces
  • Ensure SSL decryption uses a trusted CA with long validity
  • Verify all configured IPSec tunnels are operational
  • Validate tunnel load balancing where configured
  • Review QoS settings to ensure alignment with current requirements
  • Verify all licenses are active and valid for the required duration

Expected Outcome

  • Reduced unnecessary firewall sessions
  • Elimination of log loops and excessive logging
  • Clear accountability for monitoring and logging integrations
  • Improved firewall performance and operational visibility


Conclusion

By following this periodic firewall review process, the organization ensures that monitoring and logging configurations remain aligned with current operational and security requirements. Unnecessary or obsolete configurations are identified and removed in a controlled manner, reducing noise, resource consumption, and operational risk.

This KB promotes clear ownership, accountability, and disciplined documentation of all monitoring integrations. Regular adherence to this process improves firewall performance, simplifies troubleshooting, enhances monitoring effectiveness, and prevents configuration drift across environments.

Home > Enterprise security devices or applications > Firewall Periodic Review and Monitoring Configuration Guidelines

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