Ethernet Tap

Ethernet Tap

Ethernet Tap is an affordable sniffer for monitoring Ethernet traffic flowing through a single Ethernet connection. The Tap passes the Ethernet traffic through with a delay equal to about 5.2uS.

Connecting Ethernet Tap

To monitor Ethernet traffic, an Ethernet cable that was initially connecting a switch (hub) to an Ethernet device is replaced by two Ethernet cables and the Ethernet Tap is inserted between them, in what is known as a "wedge" fashion.

Ethernet Tap connection

Key Features

  • Reliably captures 10Base-T and 100Base-T Ethernet traffic.
  • Based on Intel MAX10 FPGA.
  • Six LEDs onboard:
    • Green Ready LED;
    • Green 100Mbps LED (left RJ45 jack);
    • Green 100Mbps LED (right RJ45 jack);
    • Yellow Link/Activity LED (left RJ45 jack);
    • Yellow Link/Activity LED (right RJ45 jack);
    • Blue Power LED.
  • High-speed (480Mbps) USB2.0 interface on a USB-C connector.
  • Supplied with a USB-C cable.
  • USB-powered, no additional external power necessary.
  • Compact, outside dimensions only 82 x 74 x 30 mm.
  • The product is field-upgradeable via the USB interface.

Hardware Specifications

USB:USB 2.0, high-speed (480MHz), USB-C connector
Throughput:Up to 100BaseT Ethernet's real-life throughput
Operating temperature:0 to +60 degrees C
Operating relative humidity:10% to 90%
Mechanical dimensions:82 x 74 x 30 mm


Open the Ethernet Tap plugin in IO Ninja and select a device in the Tap dropdown. Hit the Capture button, and you shall see all the packets on both RJ45 ports in real time. You can filter the packet list in the log at any time by entering a so-called pcap-filter in the Filter edit (click Apply to rebuild the log using the new filter). A complete reference on the filter syntax can be found at the official tcpdump manpage.

The Ethernet Tap plugin makes use of the new detail pane introduced in IO Ninja v3.12.0. The master log contains a list of packets (as well as other informational, warning, and error messages), a human-readable digest for each packet, and a two-liner payload preview. To inspect the raw contents of any packet, click on it in the master log, and the packet will be displayed in details in the pane below.

The color highlighting in the details pane helps you to visually distinguish between multiple protocols involved in the protocol stack for each particular packet. Clicking on any field automatically selects the corresponding region in the raw hex dump of a packet, thus making it easier for you to investigate the gory low-level details when you need to.

You can also export a log in the .pcap format for further analysis in other packet analyzers (such as Wireshark).


Hardware Manual (HTML)

This is the Ethernet Tap chapter in the IO Ninja hardware manual.

Hardware Manual (PDF)

This is a PDF rendition of the above online HTML manual for downloading and printing.