What is a firewall and its application in network environment?

Firewall (English: Firewall) is an information security system in the field of computer science. It is set between the Internet and the intranet, and monitors the communication according to the predetermined strategy of the enterprise.

The firewall can be a dedicated network device or it can run on the host to check the network transmission on each network interface. It is the most important network protection equipment at present. From a professional point of view, a firewall is a set of hardware or software that is located between two (or more) networks and realizes inter-network access or control.

function

The most basic function of firewall is to isolate the network. By dividing the network into different areas (usually called ZONE), the access control strategy between different areas is formulated to control the data flow transmitted between areas with different trust levels. For example, the Internet is an untrusted area, while the internal network is a highly trusted area. To avoid some communication prohibited by security policy.

Its basic task is to control information in different trust areas. Typical trusted areas include Internet (untrusted area) and internal network (high trust area). The ultimate goal is to provide controlled connections by running connection security policies in different levels of trust zones according to the principle of least privilege. ?

For example: TCP/IP? Port 135~ 139? Microsoft Windows? My online neighbor used it.

If the computer uses the * * * folder of the online neighbor without any firewall-related protection measures, it is equivalent to exposing its * * * folder on the Internet, and anyone has the opportunity to browse the files in the directory.

In addition, the early version of Windows also has the vulnerability of no password protection overflowing from the online neighbor system (here, the shared folder has a password, but it can be used to browse the folder without a password).

The original meaning of firewall refers to that when building and using wooden houses in ancient times, in order to prevent the occurrence and spread of fire, people piled up solid stones around the houses as barriers. This kind of protective structure building is called firewall.

In the modern network era, this metaphor refers to a defense system that isolates the local network from the external network or the local network from the Internet or the Internet, and protects the data security of the internal network by controlling and filtering restricted messages.

Extended data:

The importance of firewall

1, recording the data information in the computer network.

Data information plays a positive role in promoting the construction of computer networks, but also has a certain degree of impact on computer network security.

Through firewall technology, we can collect data transmission, information access and other aspects in the process of computer network operation, and at the same time classify and group the collected information, so as to find out the data information with security risks and take targeted measures to solve them, effectively preventing these data information from affecting the security of computer network.

In addition, after summarizing the data information recorded in the firewall, the staff can clarify the characteristics of different types of abnormal data information, which can effectively improve the efficiency and quality of computer network risk prevention and control.

2. Prevent employees from visiting websites with potential safety hazards.

A considerable number of computer network security problems are caused by staff entering websites with potential security risks. Through the application of firewall technology, the operation of employees can be monitored in real time. Once it is found that the staff is about to enter the website with security risks, the firewall will immediately call the police, thus effectively preventing the staff from entering the website with security risks by mistake and effectively improving the security of access.

3. Control unsafe services

Many unsafe services will appear in the process of computer network operation, which will seriously affect the security of computer network. The application of firewall technology can effectively reduce the actual operational risk of staff, effectively intercept unsafe services, and effectively prevent illegal attacks from affecting computer network security.

In addition, through firewall technology, we can monitor all the work in the computer network, so that all the work of computer users can be carried out in a safe and reliable environment, effectively preventing the economic losses caused by computer network problems to users.

disadvantaged

Under normal circumstances, all online package software must be filtered by firewall, which will cause the bottleneck of network traffic. For example, when offensive packets appear, attackers will send packets from time to time, which will make the firewall tired of filtering packets and make some legitimate packet software unable to enter and exit the firewall normally.

References:

Baidu encyclopedia-firewall