Basics of Computer Networks
internet connection equipment
network transmission medium

1. Basics of computer network

1. ENIAC: the birth of the world's first computer

On February 14, 1946, the University of Pennsylvania gave birth to the world first computer , called the Electronic Numerical Integral Computer (ENIAC). This computer is primarily used by the U.S. Department of Defense for ballistic calculations. Although ENIAC is bulky, has high power consumption and high heat generation, its birth has epoch-making significance . ENIAC laid the foundation for the development of computers, marking the arrival of the era of electronic computers . ENIAC is capable of complex mathematical and scientific computing tasks, providing enormous computing power for scientific research and military applications. The success of this computer promoted the further development of computer technology and laid the foundation for later computer design and manufacture.

2. Development and definition of computer network

Due to their bulky size and high price, early computers could only be owned by a few universities or laboratories, and only one user could enter the computer room for use at a time, which made it difficult to promote the application of computers. In order to solve the problems existing in the application, technicians designed to connect multiple computer terminals to the computer through communication lines, and allowed multiple users to operate the computer from the remote terminal, so the computer network was born.

Computer network refers to the connection of multiple computers with independent functions in different geographical locations and their external devices through communication lines, and realizes resource sharing and information sharing under the management and coordination of network operating systems, network management software and network communication protocols. delivered computer system.

3, Arpanet (Arpanet)" and "TCP/IP

Arpanet (Arpanet) is a packet switching network funded by the US Advanced Research Projects Agency (ARPA) in the late 1960s. It was the world's first wide area network designed to connect multiple computers and share resources. The success of Arpanet laid the foundation for the later Internet and promoted information exchange and cooperation between computers.

TCP/IP (Transmission Control Protocol/Internet Protocol) is a set of communication protocols used to transmit data in computer networks. It defines how data is grouped, transmitted, routed, and authenticated by the receiver in the network. TCP/IP is the basic protocol of the Internet, supporting data communication and resource sharing on a global scale. It provides functions such as reliable data transmission, error detection and correction, packet sequencing, etc., so that different types of computers and networks can be seamlessly connected and communicated.

The Open Interconnection Model (OSI, Open Systems Interconnection) is a reference model developed by the International Organization for Standardization (ISO), which is used to describe the communication process of computer networks. It decomposes the communication process into seven layers, namely physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer. Each layer has specific functions and protocols, and is connected to the upper and lower layers through interfaces. The OSI model provides a standardized framework that enables devices and protocols from different vendors to be compatible and interoperable.

Taken together, Arpanet and TCP/IP laid the foundation for the development of computer networks, while the Open Interconnection Model provided a common frame of reference that enabled interoperability of different types of networks. The development of these technologies and models provides important support and guidance for the construction and operation of the modern Internet.

4. Computer network classification

With the development of computer network, it has moved towards the direction of integration, diversification and high speed. More and more devices are connected to the network, and the integration between the Internet and the real world is becoming closer and closer. The development of the Internet has formed a virtual environment called cyberspace, in which people exchange information, share resources and interact socially.

Computer networks can often be classified according to their coverage and type of users.

Based on coverage, computer networks can be classified into the following categories:

Wide Area Network (WAN): A wide area network covers a wide area, usually spanning multiple geographic locations, such as cities, countries, or even the globe. The WAN connects multiple LANs or MANs through various transmission media (such as optical fiber and satellite) to realize cross-regional communication and data transmission.
Metropolitan Area Network (MAN): The coverage of a metropolitan area network is between the wide area network and the local area network, usually covering a city or a city-wide area. It provides high transmission speed and reliability to meet the communication needs within the city.
Local Area Network (LAN): A local area network has a small area of coverage, usually confined to a single building, office, or campus. A local area network connects multiple computers and devices through communication technologies such as Ethernet to realize high-speed data transmission and resource sharing.

According to the type of users, computer networks can be divided into the following two categories:

Public network : The public network refers to the Internet that provides services to the general public, and it is connected and accessed through public infrastructure and communication service providers. The public net allows users to access various resources on the Internet, such as websites, emails, social media, etc.
Private network : A private network is a private network customized for a specific organization or individual, and is usually established and managed within the organization. It can provide higher security and customized functions for realizing communication, data sharing and application services within the organization.

5. Computer network topology and components

The structure of a computer network is called network topology, which is the physical mode in which computers or devices are connected through transmission media.

Network element: A node used to connect a computer network

Transit nodes (switches, hubs, routers) that convert and exchange information
Access nodes (computer terminals, mobile terminals, servers, springboards)

Link: A connection between two nodes, usually a transmission medium connecting different nodes

Computer Network Topology

Bus topology : All nodes are connected to a shared transmission medium, such as Ethernet. Nodes communicate by sending and receiving data on the bus.

Star topology : All nodes are directly connected to a central node such as a hub, switch, or router. The central node is responsible for forwarding data and coordinating communication.

The star topology is a structure in which multiple access nodes are connected to a central node through communication links to communicate with each other. The central node manages and controls the access of different access nodes according to a centralized communication control strategy. The star topology is simple, easy to connect, easy to manage and maintain, and has strong scalability. It is currently the most widely used network structure.
Star topology limitations: high availability and reliability requirements for the central node, in a high-demand network, usually adopts a security measure of double-click backup of the central node device.

Ring topology : Each node is directly connected to adjacent nodes to form a closed loop. Data is transferred from one node to another through the ring.

Tree topology : Nodes are connected in a tree structure with a root node as the top-level node and branch nodes connected to other nodes. Data transfer starts at the root node and is passed along the branches of the tree.

Mesh topology : All nodes are directly connected to form a complex mesh structure. This topology has redundant connections, providing high reliability and redundant paths.

Hybrid topology : Combine multiple topologies to form a composite network structure. For example, interconnecting several star topologies or ring topologies.

7. Wireless LAN

Wireless local area network (WLAN) is a network technology that communicates through wireless channels, which combines wireless communication technology with network technology. Currently, the most widely used WLAN protocol is the 802.11 series of standards.

In a wireless LAN, there are several important components:

Wireless access point (Access Point, AP): It is a device that connects wireless workstations and wireless local area networks, and provides wireless signal transmission and reception functions.
Service Set Identifier (SSID): It is used to identify the wireless network, and can divide the wireless local area network into several sub-networks that require different authentication. Each subnet can set independent identity authentication, security policies and access rights.
Channel : It is the channel through which data signals are transmitted in the wireless network, usually using 13 channels. To avoid interference between signals, devices should try to use different channels.

Wireless local area network has flexibility and convenience, so that users can connect to the network in a wireless way to realize applications such as mobile office and wireless interconnection. However, due to the characteristics of wireless signals, such as limited transmission distance and susceptibility to interference, the design and deployment of WLANs require reasonable arrangements for device locations, channel selection, and security strategies to achieve stable and efficient wireless communications.

Fat "/" thin AP

The earliest APs can work independently, but they cannot coordinate with each other (for example: working channels, etc.).
Some manufacturers move their management functions to a management device, and the AP is only responsible for wireless access and Layer 2 data processing functions.
Generally, APs with simplified functions and unable to work independently are called "thin APs" or "centralized control APs", and the device that manages "thin APs" is called AC (AP Controller, AP Controller).
Correspondingly, APs with complete functions and capable of working independently are called "fat APs".
The networking architecture of AC + thin AP is suitable for scenarios with many APs. The AC can uniformly control and configure each thin AP, and the thin AP can be plug-and-play (relevant parameters can be obtained from the AC). The disadvantage is that the AC can basically only manage the thin APs of the same manufacturer, and the networking cost is relatively high.
Most home wireless routers on the market are "fat APs", and some support both fat AP and thin AP functions.

8. Wireless LAN security protection

safety management

Evaluate the application of WLAN based on the business needs of the organization, and formulate usage and management strategies;
Limit the scope of use of wireless LAN , such as only for Internet data query and daily office applications
Clearly define and limit the scope of use of the wireless LAN, and try not to transmit and process confidential and sensitive data in the wireless network.

safety technology

Set up an independent access network segment for visitors , and deploy isolation devices between the wireless LAN and the business network;
Use safe and reliable authentication and encryption technology for wireless LAN access, and use other enhanced authentication mechanisms if necessary;
Deploy an intrusion detection system to detect possible attacks and conduct regular reviews of WLAN security.

2. Network interconnection equipment

In order to achieve mutual communication and resource sharing between devices, it is not only necessary to physically connect the network, but also to resolve the differences in mutual access and communication protocols between the two networks, as well as the differences in processing speed and bandwidth. The components that are used to connect devices, networks and perform mutual negotiation and conversion are network interconnection devices.

Common network interconnection devices:

Network Interface Card (NIC):

A network interface card (Network Interface Card, NIC) is also referred to as a network card for short. It is an adapter on a computer or other network device that is used to communicate with other computers or network devices . Different types of network interface cards are designed for different types of networks, such as Ethernet, token ring, FDDI, or wireless LAN.
Each network card has a unique 48-bit serial number, also known as physical address or MAC address (Media Access Control Address). The MAC address is written in read-only memory (ROM) on the network card and assigned to the network card manufacturer by the Institute of Electrical and Electronics Engineers (IEEE). MAC addresses are used as an addressing mechanism in computer network communications.
In the OSI seven-layer model, the network card works at the second layer, the data link layer . The data link layer is responsible for transmitting data frames between adjacent nodes and implements some data link control and error detection functions. The MAC address is also the address of the second layer in network communication.

Repeater :

A repeater is a device that connects network lines , and it undertakes the bidirectional forwarding of physical signals between two network nodes . Due to the loss and attenuation of the signal in the transmission line, the digital signal or analog signal can only transmit a limited distance. Repeaters extend the distance a signal travels in a network by duplicating, adjusting, and amplifying the transmitted data signal.
Theoretically, the use of repeaters is unlimited . However, in reality, the network standard stipulates the delay range of the signal, and the repeater can only work effectively within this range, otherwise it may cause network failure . In a real production environment, many networks limit the number of repeaters that can be joined between the same pair of workstations (e.g. Ethernet is usually limited to a maximum of 4 repeaters ).
The functions of the repeater are mainly concentrated in the physical layer , including operations such as signal replication and amplification. It has no intelligent judgment function, but simply processes and forwards the signal.

Hub (Hub):

The working principle of a hub (also called HUB) is similar to that of a repeater. It is a multi-port device that broadcasts data received on one port to all other ports . A hub is also a device that works at the physical layer. Its main function is to broadcast data to all connected devices, and all devices can receive the data. However, the hub has no intelligent judgment function, and cannot perform targeted forwarding according to the address of the target device, so it will increase conflicts, collisions and bandwidth waste on the network.

Bridge :

A network bridge (also called bridger) is a store/forward device used to connect two local area networks . A bridge can divide a large LAN into multiple network segments, or connect two or more LANs, so that users on different network segments can access each other. The bridge works at the data link layer, and it needs to analyze the address field of the data frame to decide which network to forward the received data frame to. Bridges can be used for communication between devices running the same high-level protocol, and can connect networks that use different transmission media.

Switch (Switch):

A switch is a network device used for electrical or optical signal forwarding . It is a multi-port network bridge that provides exclusive signal paths for any two network nodes connected to the switch.
The most common switch is an Ethernet switch , which is used to transmit Ethernet frames in a local area network. In addition, there are other types of switches such as telephone voice switches, fiber optic switches, etc., which are used for different types of data transmission.
As a network expansion device, a switch can provide more network interfaces for a subnet to connect more computers.
It has the advantages of high cost performance, high flexibility, and easy implementation, and has become one of the most important networking devices in the network . Through the use of switches, higher data transmission rates, lower latency and more reliable connections can be achieved, improving network performance and efficiency.

Physical layering of switches:

Access layer : The access layer is located at the edge of the network, directly connecting terminal devices (such as computers, IP phones, wireless access points, etc.) to the LAN. Access layer switches usually have a small number of ports and low forwarding capabilities, and are mainly used to connect user end devices and forward data traffic to the upper aggregation layer.
Aggregation layer : The aggregation layer is where data traffic from multiple access layer switches is centrally managed and forwarded . It is usually located between the access layer and the core layer, and has stronger forwarding capabilities and more ports. The aggregation layer switch can aggregate the data of different access layers, realize the interconnection between different subnets, and provide a certain degree of policy control and security.
Core layer : The core layer is the center of the network, responsible for processing a large amount of data traffic and realizing high-speed forwarding . Core layer switches usually have higher port density, faster forwarding capabilities and more complex routing functions. It connects various aggregation layers and provides high-reliability, high-bandwidth interconnection.

Collision domains are areas where data must be sent

Collision Domain: In Ethernet, when multiple devices send data at the same time and cause data collision, these devices form a collision domain. In Ethernet, the use of hubs (Hub) to connect devices will cause the extension of the collision domain. Because hubs are dumb signal drivers that broadcast all received signals to all connected devices, conflicts can arise in this case.
Broadcast Domain: The broadcast domain refers to the range of all devices that can receive broadcast frames. In Ethernet, the broadcast frame will be forwarded by the switch (Switch), thus limiting the scope of the broadcast frame. The switch will only send broadcast frames to the interface associated with the target device, rather than broadcasting to the entire network.
Switches and hubs: Unlike hubs, switches are intelligent network devices. It forwards the data traffic from the source port to the target port according to the MAC address table, realizing the direct point-to-point transmission of data, thus effectively isolating the conflict domain. The switch can learn and remember the MAC address of the device, and only forward the data to the port where the target device is located, avoiding conflicts. Therefore, in a network composed of switches, devices under each interface belong to different collision domains.
Routers and broadcast domains: Unlike switches, routers are devices that work at the network layer and can connect different broadcast domains (that is, subnets). The router decides to forward data packets from one broadcast domain to another through the forwarding table, thus realizing the isolation between broadcast domains. Thus, routers can isolate broadcast and multicast data traffic in different broadcast domains.

The difference between a switch and a hub:

Function : The switch is a multi-port device that forwards data based on the MAC address . It can send data according to the target device and realize point-to-point transmission. Only the receiver receives the data. A hub, on the other hand, works on the physical layer, simply broadcasting the received signal to all connected devices, all of which can see the communication between other devices .
Collision domain : When using a switch to connect devices, the devices under each interface belong to different conflict domains, because the switch can isolate conflicts. When using a hub to connect devices, all network nodes connected to the hub will share the same collision domain, which may cause conflicts.
Network performance : Since the switch can transmit data point-to-point and has certain processing capabilities, it can provide more efficient and reliable data transmission and reduce conflicts and collisions. The broadcast nature of hubs can lead to increased data collisions in the network and poorer performance.

All in all, switches have more powerful and intelligent functions than hubs, and can provide better network performance and the ability to isolate conflicts. A hub is a simple physical layer device that broadcasts received signals to all connected devices.

Router :

A router is a network device that works at the third layer (network layer) in the OSI model . It is mainly responsible for the storage, grouping and forwarding of data packets between different networks . By building a flexible connection system, different data grouping and media access methods, routers can connect multiple network environments together.
A router can be connected to one or more physical network segments, and each physical network segment corresponds to a specific IP address range. Through routing tables and routing protocols, routers are able to determine the best path for a packet of data to send it from the source network to the destination network. In this way, the router realizes the communication and interconnection between the networks.
In addition to the forwarding function of data packets, the router also has some other functions, such as network address translation (NAT), firewall and load balancing . These features enhance the security, reliability, and performance of your network.

There are the following comparisons between switches and routers:

Working level : Switches work at the data link layer, while routers work at the network layer.
Function : The switch is mainly responsible for forwarding data packets according to the MAC address, while the router forwards data packets according to the IP address, and has more advanced network management and routing control functions.
Connectivity : Switches are suitable for devices that connect to the same data link layer protocol (such as Ethernet), while routers can connect to networks that implement different protocols in the lower three layers, as long as they use the same network layer protocol.
Addressing mechanism : Switches use MAC addresses as the addressing mechanism for data packets, while routers use IP addresses as the addressing mechanism for data packets.
Scale and scope : Switches are usually deployed in LANs to connect multiple devices within a LAN, while routers are used to connect different LANs or WANs to build Internet infrastructure.

Gateway :

A gateway is a complex network device, also known as a gateway or protocol converter . It is used to connect subnets implementing different protocols on the network layer to build a heterogeneous Internet. The main function of the gateway is to convert data between different communication protocols, data formats or languages, and realize communication between heterogeneous networks . In order to adapt to the needs of the destination system, the gateway needs to unpack and reconstruct the data packet.

Due to historical reasons, routers used at the network layer used to be called gateways, because most TCP/IP-based LANs use routers to access the network. Usually , therefore, the gateway referred to is the router . As technology advances, more and more devices offer similar functionality. For example, for the sake of network security, many systems now deploy firewalls at network access points. In addition to providing routing functions, firewalls also serve as gateways for the entire network to access other networks .

3. Network transmission medium

Common Network Transmission Media

A transmission line is a physical path between an information sending device and a receiving device for transferring data and signals. Different transmission media have different security features and transmission performance. The following are some common network transmission media:

1. Coaxial cable :

Coaxial cable consists of four layers: a central copper wire, a plastic insulator, a conductive mesh, and a wire sheath . The central copper wire and mesh conductive layer form a current loop for data transmission.
The salient feature of coaxial cable is that it has a wide frequency band, and the high-end frequency band can reach 10GHz, and it has good application effects in the transmission of TV signals and signal feeders.
However, coaxial cable uses a bus topology, where multiple devices are connected on a single cable. When a failure occurs in one place, it affects all the equipment on the cable, so there is a lack of reliability. Additionally, diagnosing and repairing faults can be difficult. Therefore, in practical applications, coaxial cables are gradually replaced by twisted pair wires or optical fibers , and these transmission media have more advantages in terms of reliability and maintenance.

2. Twisted pair :

Twisted pair consists of four pairs of transmission lines of different colors, and is currently the most widely used interconnection technology for LANs . Although compared with optical fiber, twisted pair has a lower transmission rate and poorer anti-interference ability, but it is widely used in network communication due to its advantages of high reliability and low cost.

In order to solve the problem of poor anti-interference ability of twisted pair, shielded twisted pair appeared . In the shielded twisted pair, the twisted pair is wrapped with a metal shielding layer, which can reduce radiation and prevent external electromagnetic interference from entering, so that the transmission is more stable and reliable.

Compared with unshielded twisted pair, shielded twisted pair has obvious improvement in anti-interference performance, and is especially suitable for scenarios that require data transmission in an electromagnetic interference environment.

With the development of technology, the transmission bandwidth of twisted pair is also expanding. From the Category 1 line that can only be used for voice transmission at the beginning to the Category 7 line that can reach 10Gbps bandwidth at present, it has well met the needs of informatization development.

At present, twisted pair cables widely used in the market mainly include Category 5, Category 5e and Category 6 cables. Category 1, 2, 3, and 4 cables have faded out of the market due to various reasons . Category 5 wires increase the winding density, and the jacket is made of high-quality insulating materials. The highest frequency bandwidth of the cable reaches 100MHz, and the highest transmission rate is 100Mbps. It is the most commonly used Ethernet cable.

Cat5e cable is mainly used for Gigabit Ethernet (1000Mbps), which has the characteristics of small attenuation, less crosstalk and small delay error.

The transmission frequency range of the Category 6 line is 1MHz to 250MHz, and its transmission performance far exceeds the Category 5 standard, and is suitable for applications with a transmission rate higher than 1Gbps.

The bandwidth of the seven-category line reaches 10Gbps, which can be used for the future ten-gigabit Ethernet.

When it comes to wiring standards for EA/TA, there are two common wiremaps: 568A and 568B.

The line sequence of the 568A standard is: green-white-1, green-2, orange-white-3, blue-4, blue-white-5, orange-6, brown-white-7, brown-8.
The line sequence of the 568B standard is: orange-white-1, orange-2, green-white-3, blue-4, blue-white-5, green-6, brown-white-7, brown-8.

Among them, "orange white" refers to light orange or cables with orange color dots or stripes on the white line, and the same is true for "green white", "brown white" and "blue white".

It should be noted that the current integrated wiring generally adopts T568A or T568B wiring standards . The difference between the two standards is that the second and third pairs are arranged differently, while the other pairs are arranged the same. The selection of the standard needs to be determined according to the specific application requirements and the compatibility of network equipment.

Question 1: Why are twisted pairs twisted in pairs?

The twisted-pair twisted pair design can reduce external electromagnetic interference and the interference of its own signal to the outside world . When two wires are twisted together, the interference signal acting on the two wires twisted together is consistent (common mode signal). In the differential circuit of the receiving signal, the common mode signal can be eliminated, thereby extracting the useful signal (differential mode signal). This differential transmission method can effectively resist external interference and improve signal transmission quality.

Question 2: Why is the twisted pair 8 wires instead of 4 wires?

The twisted pair adopts the design of 8 wires mainly for the following reasons:

Improve transmission capacity : Using 8 wires can provide higher transmission bandwidth and speed to meet higher data transmission requirements. It is very important in the network environment that requires high-speed and large-capacity data transmission.
Differential transmission : 1, 2, 3, and 6 of the 8 wires are used for differential transmission , and the signal is divided into two parts, positive and negative, for transmission. Differential transmission can improve signal anti-interference ability and transmission stability.
Spare wires and special features : 4, 5, 7, 8 wires are spare wires that can replace a faulty wire in some cases. At the same time, when using POE (Power over Ethernet) for power supply, the blue and blue-white wires can be used as positive poles (+), while the brown-white and brown wires can be used as negative poles (-).

To sum up, the design of twisted pair with 8 wires can provide higher transmission capacity, anti-interference performance and flexibility to meet the needs of different network applications .

3. Optical fiber :

Optical fibers are long, thin cylinders made of pure quartz or other exotic materials, thinner than a human hair . It has good light transmission performance, and can continuously transmit light signals on the interface of two materials through the principle of total reflection of light. In order to protect the fragility of the optical fiber, a protective layer is usually added on the outside.

An optical cable is a communication line composed of multiple optical fibers combined in a certain way and coated with a sheath material on the outside . Optical cables are designed to protect optical fibers from mechanical and environmental damage, ensuring stable and reliable signal transmission. Some cables also have an additional outer sheath for additional protection.

Optical cables are usually used for long-distance, high-speed data transmission, and are widely used in communications, networks, broadcasting and television . It has the advantages of low loss, anti-electromagnetic interference, large-capacity transmission and safe isolation, so it is considered as an advanced communication transmission medium.

Due to its unique characteristics, optical fiber communication technology has many advantages in long-distance information transmission. Compared with wired transmission technologies such as coaxial cables and twisted pairs, optical fiber communication technology has the following characteristics :

High bandwidth : Optical fiber can transmit signals in multiple frequency bands at the same time, providing high-bandwidth and large-capacity data transmission capabilities, and adapting to the rapidly growing communication needs.
Low signal attenuation : The optical fiber has very low loss during transmission, and the signal attenuation is small, which can realize longer distance transmission and maintain the stability of signal quality.
Free from electromagnetic interference : Optical fibers are not affected by electromagnetic interference, can stably transmit data in complex electromagnetic environments, and provide more reliable communication quality.
Corrosion-resistant materials : The materials used in optical fibers are usually corrosion-resistant and can be used in harsh environmental conditions, improving the reliability and life of equipment.
Light weight : Compared with traditional metal wires, optical fiber is light in weight, which makes wiring more convenient and reduces the volume and weight of equipment.
Not easy to be eavesdropped : Optical fiber transmits data through light, which will not generate electromagnetic leakage, has high security, and is not easy to be eavesdropped.

However, fiber optic communication technology also has some limitations and challenges. These include higher costs, installation and maintenance requiring professional equipment and technology, which may increase the complexity and cost of deployment and operation and maintenance. In addition, optical fibers are susceptible to damage under bending and pressure, which is more restrictive to the environment.

Generally speaking, due to its unique advantages, optical fiber communication technology has broad application prospects in long-distance and high-speed data transmission, and with the advancement of technology and the reduction of costs, optical fiber communication will be more widely used in the future .

4. Wireless transmission :

Wireless transmission is a communication method for information exchange through electromagnetic waves. The biggest feature is that it does not require connecting wires to transmit signals . In recent years, with the rapid development of wireless communication technology, wireless communication has been widely used in various fields, including WLAN, 2G, 3G, 4G, 5G, NB-IoT, LoRa, Bluetooth, RFID, etc.

The openness of wireless communication brings the freedom of communication to users, but it also brings some security risks:

Communications are vulnerable to eavesdropping : Because wireless communications use the radio spectrum for signal transmission, signals can be intercepted and eavesdropped over the air. Without proper encryption and security measures, the content of communications may be accessed by criminals.
The content of the communication can be changed : the data packets of the wireless communication may be tampered with or modified during transmission. This can lead to compromised data integrity and even trigger security risks and data breaches.
The identities of both communication parties may be impersonated : There is a risk of identity forgery in wireless communication networks, and attackers may impersonate legitimate communication participants to obtain sensitive information or perform malicious operations.

In order to deal with these security risks, wireless communication technology has adopted a variety of security measures, such as:

Encryption : By using encryption algorithms and keys, the communication content is encrypted and decrypted to ensure that only legitimate receivers can decrypt the data and read the content.
Identity authentication : By using identity authentication mechanisms, such as passwords, digital certificates, etc., to ensure that both parties to the communication are legitimate participants and to prevent identity fraud.
Security protocols : Introduce security protocols, such as SSL/TLS, into wireless communication protocols to ensure the confidentiality and integrity of data transmission during communication.
Security monitoring and vulnerability patching : monitor the wireless communication system, discover and repair possible security loopholes in time, and improve system security.

It should be emphasized that the security of wireless communication technology is a continuous challenge, and new security threats and loopholes are constantly emerging . Therefore, ensuring the security of wireless communication requires continuous research and improvement to ensure that user communication information is protected and privacy is respected.

3.1 Computer networks and network equipment

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