Engineering and technical means of information protection examples. Personal data processing cycle

Data in computer systems ah are at risk of loss due to malfunction or destruction of equipment, as well as the risk of theft. Ways to protect information include the use of hardware and devices, as well as the introduction of specialized technical means and software.

Ways of illegal access to information

The key to a successful fight against unauthorized access to information and data interception is a clear understanding of the channels of information leakage.

Integrated circuits, on which computers are based, create high-frequency changes in the level of voltages and currents. Oscillations propagate through wires and can not only be transformed into an understandable form, but also intercepted by special devices. Devices can be installed in a computer or monitor to intercept information that is displayed on the monitor or entered from the keyboard. Interception is also possible when information is transmitted via external communication channels, for example, via a telephone line.

CHECK LIST FOR INFORMATION CHANNELS

Protection methods

In practice, several groups of protection methods are used, including:

• obstacle in the path of the alleged kidnapper, which is created by physical and software means;
• control, or influencing the elements of the protected system;
• disguise, or data transformation, usually by cryptographic means;
• regulation, or the development of regulations and a set of measures aimed at encouraging users who interact with databases to behave properly;
• compulsion, or the creation of such conditions under which the user will be forced to comply with the rules for handling data;
• impulse, or creating conditions that motivate users to behave appropriately.

Each of the methods of information protection is implemented using various categories of means. Fixed assets - organizational and technical.

Technical means of information protection

The group of technical means of information protection combines hardware and software. Main:

• backup and remote storage of the most important data arrays in a computer system - on a regular basis;
• duplication and redundancy of all network subsystems that are important for data safety;
• creation of an opportunity to redistribute network resources in cases of malfunction of individual elements;
• making it possible to use backup systems power supply;
• ensuring safety from fire or water damage to equipment;
• installation of software that protects databases and other information from unauthorized access.

The complex of technical measures also includes measures to ensure the physical inaccessibility of objects computer networks, for example, such practical methods as equipping the premises with cameras and alarms.

Authentication and identification

To exclude unauthorized access to information, methods such as identification and authentication are used.

Identification is a mechanism for assigning its own unique name or image to a user who interacts with information.
Authentication is a system of ways to check if a user matches an image that is allowed access.

These tools are aimed at granting or, conversely, denying access to data. Authenticity, as a rule, is determined in three ways: by the program, by the device, by the person. In this case, the object of authentication can be not only a person, but also a technical device (computer, monitor, media) or data. The simplest way protection - password.

forgeries. According to USA Today, back in 1992, as a result of such illegal actions using personal computers US organizations suffered a total damage of $882 million. It can be assumed that the real damage was much greater, since many organizations understandably hide such incidents; there is no doubt that in our days the damage from such actions has increased many times over.

In most cases, the perpetrators turned out to be employees of organizations who are well acquainted with the working hours and protection measures. This once again confirms the danger of internal threats.

We have previously distinguished between static and dynamic integrity. For the purpose of violating static integrity an attacker (usually a staff member) can:

• enter incorrect data;
• To change the data.

Sometimes meaningful data changes, sometimes service information. Titles email can be forged; the letter as a whole can be falsified by a person those who know the password sender (we gave relevant examples). Note that the latter is possible even when the integrity is controlled cryptographic means. There is an interplay of different aspects. information security: if confidentiality is violated, integrity may suffer.

The threat to integrity is not only the falsification or modification of data, but also the refusal to take action. If there is no means to ensure "non-repudiation", computer data cannot be considered as evidence.

Potentially vulnerable to breach integrity Not only data, but also programs. Threats dynamic integrity are a violation atomicity of transactions, reordering, theft, duplication of data or the introduction of additional messages (network packets, etc.). The corresponding actions in the network environment are called active listening.

Top privacy threats

Confidential information can be divided into subject and service. Service information (for example, user passwords) does not belong to a specific subject area, it plays a technical role in the information system, but its disclosure is especially dangerous, since it is fraught with unauthorized access to all information, including subject information.

Even if the information is stored on a computer or intended for computer use, threats to its privacy may be of a non-computer and generally non-technical nature.

Many people have to act as users of not one, but a number of systems (information services). If reusable passwords or other confidential information are used to access such systems, then for sure this data will be stored not only in the head, but also in a notebook or on pieces of paper that the user often leaves on the desktop or loses. And the point here is not in the disorganization of people, but in the initial unsuitability of the password scheme. It is not possible to remember many different passwords; recommendations for their regular (if possible - frequent) change only exacerbate the situation, forcing the use of simple alternation schemes or even trying to reduce the matter to two or three easily remembered (and equally easy to guess) passwords.

The described class of vulnerabilities can be called the placement of confidential data in an environment where they are not (and often cannot be) provided with the necessary protection. In addition to passwords stored in notebooks users, this class includes the transmission of confidential data in clear text (in a conversation, in a letter, over a network), which makes it possible to intercept them. Various attacks can be used technical means(eavesdropping or listening in on conversations, passive network listening etc.), but the idea is the same - to access the data at the moment when they are the least protected.

The threat of interception of data should be taken into account not only during the initial configuration of the IS, but also, which is very important, with all changes. Exhibitions are a very dangerous threat, to which many organizations send equipment from production network with all the data stored on them. Passwords remain the same remote access they continue to be transmitted in the clear.

Another example of change is storing data on backup media. To protect data on the main media, advanced access control systems are used; copies often just lie in cabinets, and many people can access them.

Data eavesdropping is a serious threat, and if privacy is indeed critical and data is transmitted over many channels, protecting it can be very difficult and costly. The technical means of interception are well developed, accessible, easy to use, and anyone can install them, for example, on a cable network, so this threat exists not only for external, but also for internal communications.

Equipment theft is a threat not only to backup media, but also to computers, especially laptops. Often laptops are left unattended at work or in the car, sometimes they are simply lost.

A dangerous non-technical threat to privacy are methods of moral and psychological influence, such as masquerade- performing actions under the guise of a person with authority to access data.

Unpleasant threats that are difficult to defend against include abuse of power. On many types of systems, a privileged user (such as System Administrator) is capable of reading any (unencrypted) file, accessing any user's mail, etc. Another example is service damage. Typically, the service engineer has unrestricted access to the equipment and is able to bypass software protection mechanisms.

Protection methods

Existing methods and information security tools Computer systems (CS) can be divided into four main groups:

• methods and means of organizational and legal protection of information;
• methods and means of engineering and technical protection of information;
• cryptographic methods and means of information protection;
• hardware-software methods and means of information protection.

Methods and means of organizational and legal protection of information

The methods and means of organizational information protection include organizational, technical and organizational and legal measures taken in the process of creating and operating a CS to ensure information protection. These activities should be carried out during the construction or repair of premises in which the CS will be located; system design, installation and adjustment of its hardware and software; testing and checking the operability of the COP.

At this level of information protection, international treaties, by-laws of the state, state standards and local regulations of a particular organization are considered.

Methods and means of engineering and technical protection

Under the engineering and technical means of information security understand the physical objects, mechanical, electrical and electronic devices, structural elements of buildings, fire extinguishing means and other means providing:

• protection of the territory and premises of the COP from intruders;
• protection of CS hardware and information carriers from theft;
• preventing the possibility of remote (from outside the protected area) video surveillance (eavesdropping) on ​​the work of personnel and the functioning of the technical means of the COP;
• preventing the possibility of interception of PEMIN (side effects electromagnetic radiation and interference) caused by operating technical means of the COP and data transmission lines;
• organization of access to the premises of the COP employees;
• control over the mode of work of the personnel of the COP;
• control over the movement of CS employees in various production areas;
• fire protection of CS premises;
• minimization of material damage from the loss of information resulting from natural disasters and man-made accidents.

The most important component of engineering and technical means of information protection are technical means of protection, which form the first line of protection of the COP and are necessary, but insufficient condition maintaining the confidentiality and integrity of information in the CS.

Cryptographic methods of protection and encryption

Encryption is the main means of ensuring privacy. Thus, in the case of ensuring the confidentiality of data on local computer apply encryption of this data, and in the case of network interaction - encrypted data channels.

The science of protecting information through encryption is called cryptography(cryptography in translation means a mysterious letter or secret writing).

Cryptography is used:

• to protect the confidentiality of information transmitted through open communication channels;
• for authentication (authentication) of transmitted information;
• to protect confidential information when it is stored on open media;
• to ensure the integrity of information (protection of information from unauthorized changes) when it is transmitted via open communication channels or stored on open media;
• to ensure the indisputability of information transmitted over the network (preventing a possible denial of the fact of sending a message);
• to protect software and other information resources from unauthorized use and copying.

Software and hardware-software methods and means of ensuring information security

Information security hardware includes electronic and electro-mechanical devices included in the technical means of the CS and performing (independently or in a single complex with software) some information security functions. The criterion for classifying a device as a hardware, and not as an engineering and technical means of protection, is the mandatory inclusion in the composition of the technical means of the COP.

To the main hardware information security include:

• devices for entering user-identifying information (magnetic and plastic cards, fingerprints, etc.);
• devices for encrypting information;
• devices to prevent unauthorized switching on of workstations and servers (electronic locks and interlocks).

Examples of auxiliary hardware information security:

• devices for destroying information on magnetic media;
• signaling devices about attempts of unauthorized actions of CS users, etc.

Information security software means special programs included in the CS software solely to perform protective functions. To the main software tools information security include:

• programs for identification and authentication of CS users;
• programs for delimiting user access to CS resources;
• information encryption programs;
• programs for protecting information resources (system and application software, databases, computer facilities training, etc.) from unauthorized modification, use and copying.

Note that identification, in relation to ensuring the information security of the CS, is understood as the unambiguous recognition of the unique name of the subject of the CS. Authentication means confirming that the presented name matches the given subject (subject authentication).

Examples auxiliary software information protection:

• programs for the destruction of residual information (in blocks random access memory, temporary files, etc.);
• audit programs (registration logs) of events related to the security of the CS, to ensure the possibility of recovery and evidence of the occurrence of these events;
• programs for imitation of work with the offender (distracting him to receive supposedly confidential information);
• programs for test control of CS security, etc.

Results

Since potential security threats information is very diverse, the goals of information protection can only be achieved by creating an integrated information protection system, which is understood as a set of methods and means united by a single purpose and providing the necessary efficiency of information protection in the CS.

Unlike legislative and administrative ones, they are designed to get rid of the human factor as much as possible. Indeed, compliance with legislative measures is conditioned only by integrity and fear of punishment. Administrative measures are enforced by people who can be deceived, bribed or intimidated. Thus, it is possible to avoid the exact implementation of the established rules. And in the case of the use of technical means of protection, a potential adversary is faced with some technical (mathematical, physical) task, which he needs to solve in order to gain access to information. At the same time, an easier way should be available to a legitimate user, allowing him to work with the information provided to him without a decision. challenging tasks. Technical methods of protection include both a lock on a chest in which books are stored, and information carriers that self-destruct when attempted to misuse. True, such carriers are much more common in adventure films than in reality.

With regard to information security, technical methods protection are designed to provide a solution to the problems of information security.

Currently, in order to obtain confidential information, attackers, including industrial spies, use a wide variety of means and methods of infiltrating objects, developed on the basis of the latest achievements of science and technology, using the latest technologies in the field of miniaturization in the interests of their covert use. To counter this onslaught, the security services are equipped with the necessary equipment that is not inferior in reliability and functionality hacker equipment. Engineering and technical support of information security through the implementation of the necessary technical and organizational measures should exclude:

unauthorized access to information processing equipment by controlling access to production facilities;

unauthorized removal of data carriers by personnel involved in data processing through exit control in the respective production facilities;

unauthorized entry of data into memory, change or erasure of information stored in memory;

unauthorized use of information processing systems and illegal receipt of data as a result;

access to information processing systems through homemade devices and illegal acquisition of data;

the possibility of unauthorized transmission of data through a computer network;

uncontrolled data entry into the system;

processing customer data without a corresponding indication of the latter;

unauthorized reading, modification or deletion of data in the process of their transfer or transportation of storage media.

Methods for protecting information from most threats are based on engineering and technical measures. Engineering and technical protection is a set of special bodies, technical means and activities that work together to perform specific task on information protection.

Engineering and technical protection uses the following tools:

physical means;

hardware;

software;

cryptographic tools.

Physical means include various engineering means and structures that prevent physical penetration of intruders into protected objects and protect personnel (personal security equipment), material assets and finances, and information from illegal actions.

According to the level of physical protection, all zones and industrial premises can be divided into three groups:

carefully controlled areas with high level protection;

protected areas;

weakly protected areas.

Hardware includes instruments, devices, fixtures and other technical solutions used in the interests of ensuring safety.

In the practice of any organization finds wide application a variety of equipment from telephone set to perfect automated information systems supporting its production activities. The main task of the hardware is the persistent security of commercial activities.

Software is a special program software complexes and information security systems in information systems for various purposes and data processing facilities.

Cryptographic tools are special mathematical and algorithmic means of protecting information transmitted over communication networks, stored and processed on computers using encryption methods.

It is obvious that such a division of information systems security tools is rather arbitrary, since in practice they very often interact and are implemented in a complex in the form of a hardware-software implementation with extensive use of information closure algorithms.

It should be noted that the purpose of the above mechanisms can be varied. Some of them are designed to reduce the risk of threats, others provide protection against these threats, and still others detect them. At the same time, for each of the mechanisms, cryptographic methods play an important role, allowing you to create more advanced means of protection.

When creating a physical security system (as well as information security in general), there should be an analysis of threats (risks) as real (in this moment), and potential (in the future).

Based on the results of risk analysis using optimization tools, the requirements for the security system of a particular enterprise and facility in a particular environment are formed. Overstating requirements leads to unjustified expenses, understating - to an increase in the likelihood of threats.

In general, information protection by technical means is provided in the following ways:

• - the ratio of the energy of the carrier and the noise at the output of the receiver of the leakage channel is such that an attacker cannot remove information from the carrier with the quality necessary for its use;
• - the source and carrier of information are localized within the boundaries of the object of protection and a mechanical barrier is provided from contact with them by an intruder or remote impact on them by the fields of his technical means of obtaining;
• - an attacker cannot detect the source or carrier of information;
• - preventing the direct penetration of the attacker to the source of information with the help of engineering structures and technical means of protection;
• -instead of true information, the attacker receives false information, which he accepts as true. These options implement the following security methods;
• - concealment of reliable information;
• - “suggesting” false information to the attacker.

The use of engineering structures and protection is the most ancient method of protecting people and material values. Methods of protection based on engineering structures in combination with technical means of protection are also common at the present time. The combination of these methods form the so-called physical protection. But this term cannot be considered successful, since other methods of protecting information using technical means are also based on physical laws. Given that the basis of the method under consideration is engineering structures and technical means of protection, it is advisable to define it as engineering protection and technical protection of objects (IZTOO).

The main task of IZTOO is to prevent (prevent) direct contact of the attacker or the forces of nature with the objects of protection. The objects of protection are understood as people and material values, as well as information carriers localized in space. Such carriers include paper, machine carriers, photographs and film, products, materials, etc., that is, everything that has clear dimensions and weight. Information carriers in the form of electromagnetic and acoustic fields, electric current do not have clear boundaries and to protect information on these media, engineering protection methods are not acceptable - the field with information cannot be stored, for example, in a safe. Information hiding methods are used to protect information on such media.

Information hiding provides for such changes in the structure and energy of media, in which an attacker cannot directly or with the help of technical means extract information with a quality sufficient to use it in their own interests.

Distinguish between information and energy concealment. Information hiding is achieved by changing or creating a false information portrait of a semantic message, physical object or signal.

An information portrait can be called a set of elements and links between them that reflect the meaning of a message (speech or data), features of an object or signal. The elements of a discrete semantic message, for example, are letters, numbers or other characters, and the links between them determine their sequence. Information portraits of objects of observation, signals and substances are their reference characteristic structures.

The following ways of changing the information portrait are possible:

• 1. Removing some of the elements and links that form the information node (the most informative part) of the portrait;
• 2. Changing part of the elements of the information portrait while maintaining the same links between the remaining elements;
• 3. Changing or deleting links between elements of the information portrait while maintaining their number.

Changing the informational portrait of an object causes a change in its image appearance(specific unmasking signs), characteristics of the fields emitted by it or electrical signals(signs of signals), structure and properties of substances.

These changes are aimed at bringing together the feature structures of the object and the background surrounding it, as a result of which the contrast of the image of the object with respect to the background decreases and the possibilities of its detection and recognition worsen.

But when the information portrait changes, the information is not perceived not only by the attacker, but also by its authorized recipient. Therefore, for the authorized recipient, the information portrait must be restored by additionally transferring to him the deleted elements and links or the algorithm (key) of these changes. In market conditions, when a manufacturer is forced to advertise his product, the most appropriate way of information concealment is to exclude from advertising or open publications the most informative information or signs - information nodes containing a protected secret.

Information nodes include fundamentally new technical, technological and visual solutions and other achievements that constitute know-how. The removal of information nodes from the technical documentation will not allow the competitor to use the information contained in advertising or publications.

This widely used method allows:

• 1. Significantly reduce the amount of protected information and thereby simplify the problem of information security;
• 2. Use information about it in advertising new products without fear of disclosure.

For example, instead of protecting information contained in hundreds and thousands of sheets of technical documentation developed for the production of new products, only a few dozen sheets with information nodes are subject to protection.

Another method of information hiding is to transform the original information portrait into a new one, corresponding to false semantic information or a false feature structure, and to “impose” a new portrait on an intelligence agency or an attacker. This method of protection is called disinformation.

The fundamental difference between information concealment by changing the information portrait and disinformation is that the first method is aimed at making it difficult to detect an object with information among other objects (background), and the second method is aimed at creating signs of a false object against this background.

Misinformation is one of the most effective ways to protect information for the following reasons:

• - creates a reserve of time for the owner of the protected information, due to the verification of the intelligence of the reliability of the information received.
• - the consequences of decisions made by a competitor on the basis of false information may be worse for him in comparison with decisions made in the absence of obtained information. However, this method of protection is practically difficult to implement. The main problem is to ensure the reliability of a false information portrait. Disinformation will only achieve the goal when intelligence (the attacker) does not have doubts about the truth of the false information slipped to him. Otherwise, the opposite effect may be obtained, since when intelligence discloses the fact of disinformation, the received false information will narrow the search area for true information. Therefore, the organization of disinformation must be taken very seriously, taking into account the fact that consumers of information clearly understand the damage from disinformation, and at the slightest doubt will double-check information using other sources.

Misinformation is carried out by fitting the features of the information portrait of the protected object to the features of the information portrait of the false object corresponding to the previously developed version. The plausibility of disinformation largely depends on the thoroughness of the preparation of the version and the impeccability of its implementation. The version should provide for a set of measures distributed in time and space aimed at simulating the signs of a false object. Moreover, the less false information and signs are used in disinformation, the more difficult it is to reveal its false nature.

There are the following types of misinformation:

• -replacement of the details of the protected information portraits in the case when the information portrait of the protected object is similar to the information portraits of other "open" objects and does not have specific informative features. In this case, they limit themselves to the development and maintenance of a version about another object, giving out the signs of the protected object as its features. For example, at present much attention is paid to the development of dual-use products: military and civilian. The dissemination of information about the production of products for purely civilian use is a reliable cover for military options;
• -maintaining a version with features borrowed from different informational portraits real objects. It is used in cases where several tasks are being performed simultaneously in an organization. closed topics. By various combinations of signs relating to different topics, it is possible to impose on the opposite side a false idea of ​​the ongoing work without imitating additional signs;
• - a combination of true and false signs, and the insignificant, but the most valuable part of the information related to the protected object is replaced by false ones;
• - changing only the information nodes while keeping the rest of the information portrait unchanged. As a rule, various combinations of these options are used. Another effective method of hiding information is energy hiding. It consists in the use of methods and means of protecting information that exclude or hinder the fulfillment of the energy condition of reconnaissance contact.

Energy concealment is achieved by reducing the ratio of the energy (power) of signals, i.e. carriers (electromagnetic or acoustic fields and electric current) with information, and interference. Reducing the signal-to-noise ratio (the word "power", as a rule, is omitted) is possible in two ways: by reducing the signal power or by increasing the interference power at the receiver input.

The impact of interference leads to a change in the information parameters of the carriers: amplitude, frequency, phase. If the information carrier is an amplitude-modulated electromagnetic wave, and in the channel propagation medium there is interference in the form of an electromagnetic wave having the same frequency as the carrier, but random amplitude and phase, then interference of these waves occurs. As a result of this, the values ​​of the information parameter (the amplitude of the total signal) change randomly and the information is distorted. The smaller the ratio of powers, and hence the amplitudes, signal and noise, the more significant the amplitude values ​​of the total signal will differ from the original ones (set during modulation) and the more the information will be distorted.

Atmospheric and industrial interference, which are constantly present in the medium of information carrier propagation, have the greatest impact on the amplitude of the signal, to a lesser extent - on its frequency. But FM signals have a wider frequency spectrum.

Therefore, in functional channels that allow the transmission of broadband signals, for example, in the VHF band, information is transmitted, as a rule, by FM signals as more noise-resistant, and in narrow-band DV, MW and KB bands - by AM signals.

In general, the quality of received information deteriorates as the signal-to-noise ratio decreases. The nature of the dependence of the quality of received information on the signal-to-noise ratio differs for various types of information (analogue, discrete), carriers and interference, recording methods on a carrier (type of modulation), parameters of signal reception and processing means.

The most stringent requirements for the quality of information are imposed when transmitting data: the probability of a sign error for scheduled tasks, tasks of static and accounting estimated order - 10 -5 -10 -6 , but monetary data 10 -8 -10 -9 . For comparison, in telephone channels, syllabic intelligibility is provided at 60-80%, i.e. the requirements for the quality of received information are much less stringent. This difference is due to the redundancy of speech, which allows the omission of individual sounds and even syllables to restore the speech message. The probability of a sign error of 10 -5 is achieved when it is transmitted by a double AM ​​signal and the ratio of the signal power to the power of fluctuation noise at the receiver input is approximately 20, when transmitted by an FM signal - about 10. To ensure speech intelligibility of about 85%, the excess of the signal amplitude over noise should be about 10 dB, to obtain a satisfactory facsimile image quality - approximately 35 dB, a high-quality television image - more than 40 dB.

In the general case, when the signal-to-noise ratio decreases to one or less, the quality of information deteriorates so much that it cannot be practically used. For specific types of information and signal modulation, there are boundary values ​​of the signal-to-noise ratio, below which the energy concealment of information is provided.

Since the technical means of reconnaissance is usually close to the boundaries of the controlled zone of the protected object, the value of the signal-to-interference ratio is measured at the border of this zone. It is necessary to ensure that the value of the signal-to-noise ratio at this boundary is below the minimum allowable value.

Information security means is the whole line of engineering, electrical, electronic, optical and other devices and devices, devices and technical systems, as well as other products used to solve various problems of information security, including preventing leakage and ensuring the security of protected information.

In general, information security tools in terms of preventing intentional actions, depending on the method of implementation, can be divided into groups:

Technical (hardware) means of information protection. These are devices of various types (mechanical, electromechanical, electronic, etc.), which solve problems at the equipment level. information protection, for example, such a task as protecting the premises from listening. They either prevent physical penetration, or, if penetration does occur, they prevent access to data, including by masking data. The first part of the task is provided by locks, bars on windows, security alarms, etc. The second is noise generators, network filters, scanning radios and many other devices that "block" potential channels of information leakage (protection of the premises from listening) or allow them to be detected.

Software and technical information protection tools include programs for user identification, access control, information encryption, deletion of residual (working) information such as temporary files, test control of the protection system, etc.

Mixed hardware and software information security tools implement the same functions as hardware and software separately, and have intermediate properties, such as protecting the premises from eavesdropping.

Organizational means of protecting information consist of organizational and technical (preparation of premises with computers, laying a cable system, taking into account the requirements for restricting access to it, etc.) and organizational and legal (national laws and work rules established by the management of a particular enterprise).

Technical protection of information as part of an integrated security system largely determines the success of doing business. The main task of technical protection of information is to identify and block information leakage channels (radio channel, PEMIN, acoustic channels, optical channels, etc.). Solving the problems of technical protection of information requires the presence of specialists in the field of information protection and equipping departments with special equipment for detecting and blocking leak channels. The choice of special equipment for solving the problems of technical protection of information is determined on the basis of an analysis of probable threats and the degree of protection of the object.

Blockers cellular communication(suppressors cell phones), colloquially called cell jammers, is an effective means of combating information leakage over a cellular communication channel. Cellular jammers work on the principle of suppressing the radio channel between the handset and the base. The technical information leakage blocker operates in the range of the suppressed channel. Cell phone jammers are classified according to the standard of suppressed communication (AMPS / N-AMPS, NMT, TACS, GSM900/1800, CDMA, IDEN, TDMA, UMTS, DECT, 3G, universal), radiation power, dimensions. As a rule, when determining the radiated power of cell phone jammers, the safety of people in the protected room is taken into account, so the radius of effective suppression ranges from several meters to several tens of meters. The use of cellular blockers should be strictly regulated, as it can create inconvenience for third parties.