Analysis of the application of Protocol Analyzer in WLAN

The protocol analyzer is widely used in wired network and becomes a kind of useful testing and maintenance tool. In the area of WLAN, however, the problem is likely to be overlooked.

The transmission medium of WLAN is electromagnetic wave, it is almost everywhere, and there is no obvious boundary. But almost all Wi-Fi hardware has a degree of security vulnerabilities, and some simplified client configurations may not have any security guarantees. Therefore, the signal analysis in wireless transmission is very important.

Simplifies installation, operation, and protection

Some free software allows PCs to easily log into any open wireless network. The most famous of these is NetStumbler, which scans all unencrypted Wi-Fi networks and can measure the signal-to-noise ratio and throughput of each type of network. It can even connect to the GPS receiver, mapping the software, thereby searching for sites related to Wi-Fi access points to achieve free internet access. It is difficult for an enterprise IT department to find such a network security vulnerability.

Some wireless network card manufacturers also in the relevant driver software to increase the wireless scanning function. The dual-mode card provided by Proxim can simultaneously scan all appropriate channels within the 802.11a and 802.11b bands and visually display signal strength and bandwidth.

The perfect Wi-Fi protocol analyzer is much more powerful than NetStumbler or Nic-driven software, and the implementation is very different. Some protocol parsers can decode advanced protocols, includes a complete TCP/IP stack and other protocols; some focus on the bottom layer, such as detecting interference sources in the wireless spectrum, some protocol parsers can perform security alarms and have mapping tools, and some can generate low-level technical reports, or output hexadecimal codes in a spreadsheet format.

Software Wi-Fi Protocol analyzer

Most protocol parsers are based on software design. Such programmes are provided by AirMagnet AirMagnet Duo, wildpackets airopeek NX, free software ethereal, Wireless Valley Communications company Lanfielder, Baseband technology LinkFerret, network instruments Observer, Network Associates Sniffer, Wireless The Packetyzer of chemistry, and the wireless Scannner of ISS.

This type of protocol analyzer is designed based on notebooks or PDAs. Protocol analysis software for AirMagnet, Network Associates and Wireless Valley is designed for Windows CE 3 (Pocket PC) handheld devices and is less functional than notebook, but can share data with the latter. At the same time, the Pocket pc is only fit for the 802.11B protocol because the processor is weak and incapable of high speed 802.11a processing.

There are still problems in the 802.11 protocol analyzer built into the common PC, because the Windows system does not support the 802.11 protocol, requires the driver software to convert 802.11 frames to the regular Ethernet frame signal, which can be recognized by PC. A protocol analyzer also cannot support all vendors ' network adapters (or chipsets), and a slightly more powerful protocol analysis software can support network adapters based on similar chipsets, such as many software support Intersil Prismⅱ chips.

In addition, most protocol parsers require smart card support, which is incompatible with the Wi-Fi protocols of many high-end notebooks. The Airopeek solution provided by WildPackets company is better in this respect, the smart card supports the Intel miniPCI interface and supports the 802.11A protocol. Software parsers tend to lag behind Wi-Fi devices in development because they need to rebuild drivers for matching smart cards.