Multi-Tap Network Packet Capturing

Overview

This section will demonstrate the use of Multi-Tap Network Packet Capture with NST. The NST WUI implementation supports simultaneous Packet Capture on up to 4 network interfaces (Quad Tap) per multi-tap capture session. NST uses the Wireshark network protocol analyzer suite for network packet capture. The light-weight network packet capture tool: "dumpcap" is used as the capture engine.

When capturing packets at Gigabit Ethernet rates and one needs total visibility on the link, then a passive tap is required. Net Optics, a global leader in passive monitoring, makes an excellent 10/100/1000BaseT Tap (TP-CU3) for passively allowing access to monitor GigaBit traffic.

Multi-Tap Network Packet Capture: NAT/PAT Traffic

The diagram depicted below shows an example Multi-Tap Capture Setup for monitoring GigaBit traffic across a firewall boundary. We will explore the capturing of packets as they transverse the firewall and undergo both Network and Port Address Translation.

File:Nst quad tap networking2.png

Multi-Tap Network Packet Capture: Traffic Between Gigabit Switches

The diagram displayed below shows an example Dual-Tap Capture Setup for monitoring network traffic between 2 Gigabit switches. In this case a generic notebook computer was used and configured with 3 network interfaces (A built-in Gigabit LAN adapter, a Gigabit LAN adapter PC-Card and a built-in 802.11g/n wireless adapter for secure remote access and control of NST).

Example Multi-Tap Network Packet Capture Session: Step-By-Step

This section will demonstrate a Multi-Tap Network Packet session using 2 network interfaces (eth1 and eth2) as the target capture interfaces. We will concentrate on email traffic (POP and SMTP). It is assumed that the NST probe is