Evidence, packet captures, and a bounded troubleshooting method
Start by defining the failure precisely. Record the affected source and destination, application, protocol, direction, time, expected behavior, and actual symptom. Ask what changed and whether the problem affects every flow or only a subset. A complaint that the firewall is down may describe DNS failure, a rejected application login, asymmetric routing, or a management-console problem rather than a complete forwarding outage. Establish a reproducible test before changing configuration. Record the device, software release, relevant context, and time basis so that evidence from different systems can be compared.
Build and test a hypothesis. Follow the packet path from the client through the relevant interfaces and policy decisions to the server and back. A successful ping establishes a limited observation about ICMP reachability, not proof that a TCP service is listening or that an application transaction succeeds. Likewise, a TCP connection can complete while TLS or authentication fails later. Separate layers and observe the boundary at which expected behavior stops. Change one justified variable at a time, define a success criterion, and keep a practical rollback plan.
Use tools for the question they can answer. Interface packet capture can show traffic observed at the selected point. FW Monitor provides Check Point inspection-path visibility, subject to the actual processing architecture and supported capture options. CPView provides operational performance statistics, while CPInfo collects diagnostic information useful for support. A running process or an accepted connection log is valuable evidence but not a complete application test. Verify command syntax and applicability in the R82 guide rather than copying an option from another platform or release.
Capture deliberately. Filter by the relevant hosts, protocol, and ports, choose the correct interface and context, and bound duration and output size. Name resolution can obscure addresses or slow display, so numeric output is often useful. Account for address translation, encapsulation, and the return direction when constructing a filter. An empty capture may mean the filter or observation point is wrong; it is not automatically proof that no packet exists anywhere. Protect captures because they can contain credentials, personal data, or confidential payloads.
Correlate evidence instead of relying on a single screenshot. Compare timestamps, policy versions, packet tuples, counters, and endpoint observations. Distinguish a cumulative counter from a rate and a historical sample from current behavior. A large debug can consume resources and expose data; use a narrowly scoped, authorized procedure with a stop condition. Preserve useful evidence before a disruptive restart when feasible. Close the investigation by retesting the original application flow, checking related paths, documenting the cause and change, and confirming that temporary diagnostics have ended.