Скачать или смотреть tcpdump and fw monitor in checkpoint firewall

Both tcpdump and fw monitor are valuable tools for capturing and analyzing network traffic on a Check Point firewall, but they serve slightly different purposes. tcpdump primarily captures traffic as it enters or leaves a specific interface, while fw monitor provides a more detailed view of the traffic flow through the firewall's inspection process, including routing and NAT decisions.

Here's a more detailed breakdown:

tcpdump:
Captures traffic at the interface level:
It shows packets entering and leaving the firewall's interfaces.

Promiscuous mode:
tcpdump usually operates in promiscuous mode, meaning it captures all traffic seen on the interface, not just traffic destined for the firewall.

Limited inspection:
It doesn't show how the firewall processes the traffic internally (routing, NAT, etc.).

Example:
tcpdump -i eth0 -n port 80 would capture all traffic on interface eth0 going to or from port 80.

fw monitor:
Captures traffic at different inspection points:
fw monitor shows traffic at various stages of the firewall's processing pipeline, including pre-inbound, post-inbound, pre-outbound, and post-outbound (denoted by i, I, o, and O respectively).

Detailed inspection:
It reveals routing, NAT, and other firewall-related processing that tcpdump doesn't.

Non-promiscuous:
fw monitor doesn't require promiscuous mode, making it potentially more secure.

Example:
fw monitor -m iIoO would capture traffic at the four main inspection points.


When to use which tool:

tcpdump:
Useful for basic traffic capture and troubleshooting network connectivity issues at the interface level. Also useful for capturing traffic from a specific interface with filters.

fw monitor:
Essential for understanding how the firewall processes traffic, debugging routing and NAT issues, and analyzing the impact of security policies on traffic flow.

Important Considerations:

SecureXL:
If SecureXL is enabled, it can bypass some of the inspection points that fw monitor would normally show. You may need to temporarily disable SecureXL to see the complete traffic flow.

Performance:
Running a fw monitor can impact performance, especially with high traffic volumes or complex rulesets. Consider the impact on the firewall's performance when using it.

Packet Capture Tools:
Check Point also provides other tools like cppcap, a combination of tcpdump and fw monitor that can simplify some tasks.

In essence, tcpdump is a more general-purpose tool for network capture, while fw monitor is specifically designed for in-depth analysis of traffic flow through a Check Point firewall.