Advanced Firewall Troubleshooting

This chapter has focused primarily on the core tasks of a firewall to process traffic through the firewall and for the firewall to provide for connectivity and access to remote and protected hosts. However, firewalls continue to gain more advanced features and functions, and it is becoming necessary to troubleshoot those advanced features and functions.

Processes such as SNMP, NTP, routing, and authentication all provide ample opportunity for something to fail that you will need to troubleshoot, diagnose, and repair. The key to troubleshooting these advanced features relies on you undertaking a couple of steps:

Step 1.	Ensure that you understand the process in question and how it functions. For example, if the firewall is going to use NTP, make sure that you know how NTP functions so that you know how to begin troubleshooting any problems that may occur.
Step 2.	Develop troubleshooting checklists that are relevant to the processes and functions in question. For example, although most of the generic firewall troubleshooting checklist steps may be relevant, if you need to troubleshoot SNMP, you need to consider SNMP-specific troubleshooting steps to complement the standard troubleshooting checklist that you will adhere to.