[IOT] intelligent hardware: how to obtain the WiFi signal strength of hardware products

Use Microsoft Network Monitor（NM） When a tool grabs a packet , Get smart hardware devices （wifi modular ） Of IP The address is not very convenient . The packet capturing tool will be described in detail below ！

To solve this problem , Wei Sir Make your laptop a hot spot , Let intelligent hardware or wifi The module is connected to the hotspot , This makes it easy to get IP Address .

open NM Caught tools ： Grab packet

 

NM Tool is introduced ：

Microsoft Network Monitor（NM） It is a free network protocol data analysis tool attached to Microsoft （Microsoft Network Monitor）, It can not only capture packets , And do some simple analysis functions based on packet capture records .NM It should be based on libpacp and winpacp developable , The default is that the hybrid mode is not enabled , So when capturing packets , Only multicast can be fetched by default , radio broadcast , Or the receiver is a local packet . That is, it's better to connect locally first AP, And then grab the packets , Otherwise, only some beacon and probe Information about . If you want to grab more packets , Then you have to be in NM Manually turn on the hybrid mode .

Because there is nothing special about the installation process , So here we just skip . After installing the software , We can open it and try to capture it ：

You can see that multiple interfaces in the computer have been identified , Because we mainly capture wireless data packets , So choose the wireless network card . As shown here Friendly Name The direct correspondence is the name of the network adapter , So it is not necessarily named wireless network card , You need to check it out Description Is there... In it Wireless The words... .

Then create a new packet capture

Here's the picture , After creating a new packet capture , We can directly grab data frames

The red box above contains several options ：“Capture Settings”,“Start”,“Pause” and “Stop”.

After choosing , Press start Just start to grab the bag , If you haven't chosen before Monitor Mode Words , By default Local Mode（ That is not a hybrid pattern ） Carry out the bag , What we catch is actually local and corresponding AP Some data packets for specific communication .
In the diagram above , On the left is NM Some data packet interactions parsed according to different applications , That is, its analysis function . In the middle of the right is the captured packet , The following is the original binary file of the specific data package and the parsed content . stay Tools->Options->Parser Profiles Next , You can select a specific parser , But in general , We don't need any extra changes here .

that NM The packet parsing function of can still meet many basic needs , And the display is quite clear . Here is a Beacon Frame resolution ,MetaData Some physical layer parameters （ Be similar to Radiotap）, And then there was 802.11 MAC Frame header of layer （ contain FrameControl,Duration,DA,SA,BSSID,SequenceControl）, Then it's concrete Beacon Manage the frame body of the frame （ Contains the timestamp for synchronization （TimeStamp）,AP Supported working capabilities and some specific functional information blocks , such as SSID,TIM,RSN wait ）, The details will be expanded later when we discuss data frames .

NM You can also directly save the data package as “.cap” The format of , stay File->Save As Next choice , In this way, the captured packets can be saved first , And then use Wireshark perhaps Omnipeek And other commonly used software .

This is the same as the regular Wireshark It's almost time to parse the packet , And you can see , Because it uses NM A bag snatcher , So there will be one more NetMon 802.11 capture header, Actually 802.11 radio information Through this header Resolved .

Download address ： Download address

so Microsoft Network Monitor（NM） It can be used as a lightweight and easy-to-use packet capturing tool , Directly in any Windows You can install , And does not require the support of a specific network card , The results of capturing packets can also be saved , And pass NM Itself or Wireshark To analyze , For learning 802.11 The agreement is quite helpful .

# Columnist #

Wei Sir, official account ： Jianyi business , Everyone is a product manager columnist . Focus on the field of intelligent hardware , Good at market analysis 、 Product design and development 、 Production management, etc , Like reading and mountain climbing .