CN113794531B - Preamble-based WiFi channel interference method and system for preventing eavesdropping - Google Patents
Preamble-based WiFi channel interference method and system for preventing eavesdropping Download PDFInfo
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- 230000002452 interceptive effect Effects 0.000 claims description 8
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K3/00—Jamming of communication; Counter-measures
- H04K3/80—Jamming or countermeasure characterized by its function
- H04K3/82—Jamming or countermeasure characterized by its function related to preventing surveillance, interception or detection
- H04K3/825—Jamming or countermeasure characterized by its function related to preventing surveillance, interception or detection by jamming
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K1/00—Secret communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K3/00—Jamming of communication; Counter-measures
- H04K3/60—Jamming involving special techniques
Abstract
The application discloses a WiFi channel interference method and system based on a preamble, wherein the method enables all wireless local area network devices of the channel to judge that the current channel is busy by continuously transmitting a short training field (L-STF) in an IEEE802.11 protocol preamble in a designated channel so that the network communication cannot be performed by utilizing WiFi. The interference system can realize accurate interference on the designated channel and full-band interference in the 2.4G or 5GWiFi frequency band. The accurate interference of the designated channel is achieved by scanning the wireless local area network parameters in the current network environment, selecting the channel in which the interference target is located, amplifying the interference signal through the power amplification module, and attacking the channel, so that all wireless local area network devices nearby the channel cannot conduct normal network communication, and the possibility that other people steal privacy and safety by utilizing WiFi is effectively eliminated.
Description
Technical Field
The application relates to the technical field of wireless networks, in particular to a preamble-based WiFi channel interference method and system for preventing eavesdropping.
Background
With the development of the mobile internet and the continuous increase of the number of terminals, the application of technologies such as the internet of things, artificial intelligence, big data, edge computing and the like, the wireless network bearing capacity is in face of unprecedented demands. Meanwhile, the new epidemic situation affects the world, the pace of ICT construction is promoted from the other aspect, the digitized transformation pace is accelerated in each mainstream industry such as education, medical treatment, manufacturing, finance and the like to cope with the remarkable huge change, the projects such as teleoffice, online education, digital platforms, intelligent medical treatment and the like also need strong wireless network support, and the latest generation of WiFi equipment has the product characteristics of the epoch-making industry, and can face the novel business demands of high speed, intelligence and high concurrency.
At present, the consumption level WiFi6 router already occupies 14.7% of router market share, the epidemic situation also promotes the entertainment game industry and the network demand of the digital television, and WiFi6 also provides high-quality network experience for consumption level users. IDC prediction, 2021, consumer grade router WiFi6 products will continue to expand market share, reaching a market size of nearly $ 8.5 billion in the chinese market.
However, with the popularization and promotion of WiFi, the potential safety hazard exposed by WiFi is also more and more serious. For example, lawbreakers may connect pre-installed eavesdropping devices using a WiFi network and constantly transmit confidential information that violates personal privacy, affecting social security.
For such problems, the conventional processing method uses two kinds of interference signals, the first kind of interference signal is called persistent interference, the interfered link layer signal is formed by random bit stream, and the interference signal is transmitted after being processed by the physical layer modulation and power amplification module, the second kind of interference signal is called deceptive interference, the interference signal complies with IEEE802.11 protocol, and the interference frame is transmitted uninterruptedly to make the sender device mistakenly busy as a channel and unable to transmit data, thereby finally playing the effect of blocking the channel. However, both methods have the defects of large power consumption, unobvious interference effect and incapability of realizing full-band coverage.
Thus, there is an efficient interference method for designated channels and an overall need for 2.4G or 5G full band interference, there is an overall need for a complete system that achieves stable sustained WiFi channel interference with lower power consumption.
Disclosure of Invention
In order to solve the problems, the invention discloses a WiFi channel interference method based on a preamble for preventing eavesdropping, which comprises three steps of obtaining current environment WiFi network parameters, generating an L-STF interference signal and continuously transmitting the interference signal in a target channel, wherein the three steps are as follows:
acquiring the current environment WiFi network parameters comprises scanning a WiFi channel, acquiring a becon frame, analyzing the becon frame and acquiring relevant information of WiFi equipment.
Generating the L-STF interference signal includes generating an L-STF time domain signal and placing the generated signal into a memory.
Transmitting the interfering signal on the target channel includes transmitting the interfering signal on a designated channel and transmitting the interfering signal on a full frequency band.
The invention is further improved in that: the specific steps of acquiring the WiFi network parameters of the current environment are as follows: and scanning surrounding wireless network environments by using a wireless network card, scanning each channel in turn, acquiring becon frames sent by different WiFi devices, analyzing the becon frames according to an IEEE802.11 protocol, and acquiring SSIDs (service set identifier) of the different WiFi devices and the channel where the SSID is located.
The invention is further improved in that: the specific method for generating the L-STF interference signal comprises the following steps: following the IEEE802.11 protocol, a time domain signal is generated using an inverse fourier transform function using 12 subcarriers into OFDM, and the generated time domain signal is repeated 10 times to constitute an L-STF frame in the preamble for a duration of 8us.
The invention is further improved in that: the specific method for interfering the appointed frequency band comprises the following steps: and continuously transmitting the interference signal on the target channel by acquiring the channel where the nearby target WiFi equipment is located.
The invention is further improved in that: the specific method for carrying out interference on the full frequency band comprises the following steps: in the frequency band of 2.4g, the L-STF interference signal is required to be sent on three channels of 3, 7 and 11 so as to realize the signal coverage of the full frequency band. In the 5g frequency band, the L-STF interference signal is required to be sent on 13 channels, so that the signal coverage of the full frequency band can be realized.
A preamble based WiFi channel interference system for anti-eavesdropping, comprising:
an input unit: the method comprises the steps of selecting a target needing to transmit interference, and transmitting an interference signal on a channel where the interference target is located; for selecting full band interference.
And a display unit: for displaying the SSID scanned to the wireless device and the channel on which it is located.
A memory: the method is used for storing a complete interference program and time domain sampling values of interference signals, and the interference program realizes a WiFi channel interference method based on a preamble.
A processor: and communicating with each module to execute the interference program in the memory.
WiFi signal acquisition module: for scanning and capturing becon frames transmitted by wireless devices on different channels in space, and for delivering parsed becon frames to a processor.
The interference signal output module: for outputting the L-STF interference signal at a designated channel, a plurality of output modules may output the interference signal at a plurality of channels in parallel.
Interference signal amplification module: the power amplifier is used for amplifying the power of the interference signal, improving the interference effect and the interference range, realizing through-wall interference, and the number of the amplifying modules is consistent with that of the output modules.
The invention has the beneficial effects that:
compared with the traditional WiFi interference method, the CCA mechanism of the wireless device can be triggered by a lower signal energy threshold, so that the wireless device can judge that a channel is busy and cannot normally communicate, therefore, the interference signal strength requirement is lower, the power consumption requirement on the interference device is greatly reduced, the interference effect is obvious, and the interference effect is a certain through-wall interference effect.
Drawings
Fig. 1 is a flow chart of a WiFi channel interference method based on a preamble;
FIG. 2 is a flow chart diagram of an implementation of an interference method;
fig. 3 is a block diagram of a WiFi channel interference system based on a preamble;
fig. 4 is a time domain waveform diagram of an L-STF interference signal;
fig. 5 is a schematic diagram of 2.4g wifi channel interference coverage;
fig. 6 is a diagram of an ieee802.11ac physical layer packet structure.
Detailed Description
The present invention is further illustrated in the following drawings and detailed description, which are to be understood as being merely illustrative of the invention and not limiting the scope of the invention. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings, and the words "inner" and "outer" refer to directions toward or away from, respectively, the geometric center of a particular component.
As shown in fig. 1, a method for preventing interception by using a WiFi channel based on a preamble includes three steps of obtaining a current environment WiFi network parameter, generating an L-STF interference signal, and continuously transmitting the interference signal on a target channel.
Acquiring the current environment WiFi network parameters comprises scanning a WiFi channel, acquiring a becon frame, analyzing the becon frame and acquiring relevant information of WiFi equipment.
Generating the L-STF interference signal includes generating an L-STF time domain signal, and forming a complete signal with 10 repeated sequences.
Transmitting the interfering signal on the target channel includes transmitting the interfering signal on a designated channel and transmitting the interfering signal on a full frequency band.
As shown in fig. 2, the specific implementation method is as follows:
scanning surrounding wireless network environments, scanning each channel to obtain becon frames sent by different WiFi devices, analyzing the becon frames to obtain SSIDs (service set identifier) and channels of the different WiFi devices, and specifically comprising the following steps of:
(1) Firstly, scanning surrounding wireless network environments by using a wireless network card;
(2) Scanning each channel in turn;
(3) Acquiring becon frames sent by different WiFi devices;
(4) Parsing the becon frame in compliance with IEEE802.11 protocol;
(5) Acquiring SSIDs of different WiFi devices and channels;
(6) And outputting the SSID and the channel through a display unit.
As shown in fig. 6, the L-STF interference signal belongs to a part of the IEEE802.11 physical layer preamble, and is generally used for packet detection, coarse synchronization, and automatic gain control.
The specific method for generating the L-STF interference signal comprises the following steps: following the IEEE802.11 protocol, using 12 subcarriers in OFDM, generating a time domain signal using an inverse fourier transform function, repeating the generated time domain signal 10 times to form an L-STF frame signal in a preamble, and generating a time domain waveform of an interference signal with an interference signal duration of 8us as shown in fig. 4, which comprises the following specific steps:
(1) Defining subcarrier sequence L_STF = [ solution 0,1+1i,0, -1i,0, 1+1i,0, -1i,0, -1i,0, 1+
1i,0,0,0,0,0,0,0,-1-1i,0,0,0,-1-1i,0,0,0,1+1i,0,0,0,1+
1i,0,0,0,1+1i,0,0,0,1+1i,0,0,0,0,0,0,0]；
(2) The inverse fourier operation is performed to obtain a time domain signal l_stf_time, where l_stf_time is a sequence with a repetition length of 64 and is 16 elements, that is, the sequence includes 4 repeated sequences:
L_STF_time＝ifft(L_STF,64)；
(3) Splicing the sequences to obtain a sequence containing 10 repeated code elements, namely a final L-STF sequence:
L_STF_time＝[L_STF_time,L_STF_time,L_STF_time(1:32)]；
the user selects to interfere with the designated channel or the full frequency band through the input unit.
The specific method for carrying out interference on the appointed frequency band comprises the following steps: and outputting the generated interference signal at a sampling rate of 20Mhz, wherein the center frequency is the center frequency of the frequency band.
The specific method for carrying out interference on the full frequency band comprises the following steps: in the 2.4g frequency band, as shown in fig. 5, the L-STF interference signal needs to be sent on three channels of 3, 7 and 11 to realize the signal coverage of the full frequency band. In the 5g frequency band, taking China as an example, the L-STF interference signals are required to be sent on 13 channels to realize the coverage of the full frequency band.
As shown in fig. 3, the present invention further provides a WiFi channel interference system based on a preamble for preventing eavesdropping, including:
an input unit: the method comprises the steps of selecting a target needing to transmit interference, and transmitting an interference signal on a channel where the interference target is located; full band interference is selected.
And a display unit: for displaying the SSID of the scanned wireless device and the channel on which it is located.
The input unit and the display unit adopt capacitive touch screens, the processor transmits data to be displayed to the touch screens through serial communication, and the communication flow follows the communication protocol of the capacitive touch screens. When the user selects a channel needing interference, the touch screen transmits the selected result to the processor through serial communication.
A processor: and communicating with each module to execute the interference program in the memory.
A memory: the method is used for storing a complete interference program and time domain sampling values of interference signals, the interference program realizes a WiFi channel interference method based on a preamble, and comprises three steps of obtaining current environment WiFi network parameters, generating L-STF interference signals and continuously transmitting the interference signals on a target channel, wherein the interference signal data storage form is 160 single-precision floating point numbers.
WiFi signal acquisition module: the invention uses a WiFi network card supporting IEEE802.11ac protocol to capture WiFi signals in space, and the network card analyzes data according to IEEE802.11 protocol.
The interference signal output module: the output modules are used for outputting L-STF interference signals on specified channels, the interference signals can be output on the channels in parallel, the output modules use radio frequency chips supporting WiFi2.4g or 5g frequency bands, and the signal output bandwidth of the chips is at least 20MHz.
Interference signal amplification module: the power amplification circuit is used for amplifying the power of an interference signal, improving the interference effect and the interference range, realizing through-wall interference, wherein the number of the amplification modules is consistent with that of the output modules, the signal amplification modules comprise a power amplification circuit and a transmitting antenna, the power amplification circuit is used for amplifying the power of a high-frequency signal with the frequency range of 2.4g or 5g, and the antenna is used for converting a circuit signal into an electromagnetic wave signal.
The technical means disclosed by the scheme of the invention is not limited to the technical means disclosed by the embodiment, and also comprises the technical scheme formed by any combination of the technical features.
Claims (8)
1. A preamble based WiFi channel interference method for preventing eavesdropping, characterized in that: the method comprises the following steps:
step 1: acquiring current environment WiFi network parameters;
step 2: generating an L-STF interference signal; generating an L-STF time domain signal, and placing the generated signal into a memory; the step 2: the specific method for generating the L-STF interference signal comprises the following steps: generating a time domain signal by using 12 subcarriers in OFDM (orthogonal frequency division multiplexing), and repeating the generated time domain signal for 10 times to form an L-STF frame signal in a preamble, wherein the duration is 8us;
step 3: the interference signal is continuously transmitted on the target channel.
2. A preamble based WiFi channel interference method for anti-eavesdropping according to claim 1, wherein: the step 1: the specific steps for acquiring the WiFi network parameters in the current environment are as follows: and scanning surrounding wireless network environments by using a wireless network card, scanning each channel in turn, acquiring becon frames sent by different WiFi devices, analyzing the becon frames according to an IEEE802.11 protocol, and acquiring SSIDs (service set identifier) of the different WiFi devices and the channel where the SSID is located.
3. A preamble based WiFi channel interference method for anti-eavesdropping according to claim 1, wherein: the step 3: continuously transmitting the interfering signal at the target channel includes: the interference signal is transmitted on the selected target channel and the interference signal is transmitted on the full frequency band.
4. A preamble based WiFi channel interference method for anti-eavesdropping according to claim 3, wherein: the specific method for transmitting the interference signal in the full frequency band comprises the following steps: in the 2.4g frequency band, the L-STF interference signal is required to be sent on three channels of 3, 7 and 11 so as to realize the signal coverage of the full frequency band; in the 5g frequency band, the L-STF interference signal needs to be sent on 13 channels in total so as to realize the signal coverage of the full frequency band.
5. A preamble-based WiFi channel interference system for preventing eavesdropping, for performing the method of claim 1, comprising an input unit, a display unit, a memory, a processor, an interference signal output module, and an interference signal amplification module.
6. A preamble based WiFi channel interference system for anti-eavesdropping according to claim 5, wherein:
the input unit is used for selecting a target channel needing interference and transmitting an interference signal on a channel where an interference target is located; for selecting full band interference; the display unit is used for displaying the scanned SSID of the wireless device and the channel where the SSID is located.
7. A preamble based WiFi channel interference system for anti-eavesdropping according to claim 5, wherein:
the memory is used for storing a complete interference program and a time domain sampling value of an interference signal, and the interference program realizes a WiFi channel interference method based on a lead code, and the method comprises three steps of obtaining current environment WiFi network parameters, generating an L-STF interference signal and continuously transmitting the interference signal in a target channel; the processor is used for communicating with each module and executing the interference program in the memory.
8. A preamble based WiFi channel interference system for anti-eavesdropping according to claim 5, wherein: the system also comprises a WiFi signal capturing module, wherein the WiFi signal capturing module is used for scanning and capturing becon frames sent by wireless equipment on different channels and transmitting the parsed becon frames to the processor; the interference signal output module is used for outputting L-STF interference signals in a designated channel, a plurality of output modules can output the interference signals in parallel in a plurality of channels, and the number of the output modules is determined by the number of target channels; the interference signal amplifying module is used for amplifying the power of the interference signal, improving the interference effect and the interference range, realizing through-wall interference, and the quantity of the amplifying modules is consistent with that of the output modules.
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| CN103051411A (en) * | 2012-12-05 | 2013-04-17 | 上海物联网有限公司 | Wireless local area network interference unit and implementation method thereof |
| CN103117833A (en) * | 2012-12-05 | 2013-05-22 | 上海物联网有限公司 | Shielding device and shielding method of wireless local area network |
| CN110121870A (en) * | 2017-01-09 | 2019-08-13 | 高通股份有限公司 | Receiver adaptation is carried out using the duplicate sequence of pilot tone |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103051411A (en) * | 2012-12-05 | 2013-04-17 | 上海物联网有限公司 | Wireless local area network interference unit and implementation method thereof |
| CN103117833A (en) * | 2012-12-05 | 2013-05-22 | 上海物联网有限公司 | Shielding device and shielding method of wireless local area network |
| CN110121870A (en) * | 2017-01-09 | 2019-08-13 | 高通股份有限公司 | Receiver adaptation is carried out using the duplicate sequence of pilot tone |
Non-Patent Citations (1)
| Title |
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| Efficient jamming attacks in Wi-Fi networks based on legacy short training field;Ruichi Zhu et al.;ICoCTA 2022;全文 * |
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