What is a LAN Network?

The coverage of a local area network is generally within a few kilometers, and its convenient installation, cost saving, and easy expansion make it widely used in various offices. The local area network can implement functions such as file management, application software sharing, and printer sharing. During the use process, by maintaining the security of the local area network, it can effectively protect data security and ensure that the local area network can operate normally and stably. ^[1]

A local area network is naturally a regional network formed in a local area. It is characterized by a limited distribution area, which can be large or small, as large as the connection between a building and an adjacent building, and as small as an office connection. Compared with other networks, the LAN itself has faster transmission speed, more stable performance, simple framework, and closedness, which is why many organizations choose it. The composition of the local area network is generally composed of computer equipment, network connection equipment, and network transmission media. Most of the computer equipment includes

Wireless local area network, referred to as WLAN, is a computer network formed by interconnecting computers in company buildings or shopping malls within a few kilometers. A wireless local area network can support the use of several to thousands of computers. There are more and more applications of wireless local area networks. Now campuses, shopping malls, companies, and high-speed rail are in use. The application of wireless local area network has brought great help to our lives and work, not only can quickly transmit the information that people need, but also make people's connection to the Internet faster and more convenient. ^[5]

Wired LANs use a variety of different transmission technologies. Most of them use copper wire as the transmission medium, but some also use optical fiber. The size of the local area network is limited, which means that the transmission time in the worst case is also bounded and can be known in advance. Understanding these boundaries helps in the design of network protocols. Generally, wired LANs operate at speeds between 100 Mbps and 1 Gbps, with low latency (microseconds or nanoseconds), and few errors occur. Newer LANs can operate at rates up to 10Gbps. Compared with wireless networks, wired LANs surpass them in all aspects of performance. ^[3]

The local area network is generally owned by a department or unit. Network construction, maintenance, and expansion are relatively easy, and the system is highly flexible. Its main features are:

1. The geographical scope covered is relatively small, and it is only interconnected in a relatively independent local area, such as a single or concentrated building complex.

2. Use specially laid transmission media for networking, high data transmission rate (10Mb / s 10Gb / s)

3. Short communication delay time and high reliability

4. LAN can support multiple transmission media

Local area networks are usually distributed within a limited geographical area

Weak LAN server protection

Compared with other networks, the local area network has a faster information transmission speed and a relatively simple transmission method. If a computer in a local area network is invaded by a virus, the virus will spread to all computers through the information transmission in the local area network. Although some anti-virus software will be installed in some LANs, because the software patches are not updated or some computers do not have anti-virus software installed, the virus will use the vulnerability of the protection software to conduct network attacks, which will cause the LAN system to run down and cause user information to leak , Stealing user property. ^[8]

LAN network border access risks

The access risks that exist at the LAN network boundary mainly include damage to routes, eavesdropping of user information, unauthorized access to network equipment, and the spread of certain viruses. For the operation of the local area network, there are more denial-of-service attacks, which cause the host to freeze and network services to be suspended. And a large number of junk data packets generated after a large number of attacks such as SYNFlood, ACKFlooding, UDPFlood, etc., make the victim's CPU run at full capacity or lack of memory, resulting in business interruption of key equipment of the business server or degradation of service quality. ^[8]

LAN users have weak security awareness

When LAN users use the network for data transmission, they sometimes use external storage devices. However, users do not have the habit of detecting external devices securely, but directly connect to the network for use. As a result, external data enters the local area network with the virus, and the spread of the information in the local area network causes the virus to spread in the local area network, thereby causing a situation where the local area network virus invades. In addition, some users accidentally click on some pop-up windows or download software pretending to be viruses during the browsing of the website, which will also cause computer poisoning, cause users' information leakage, and threaten the security of the entire local area network. ^[8]