What is the role of a firewall? What are the main technologies used to implement firewalls?

The main function of the firewall is to ensure network boundary security. The main technologies used to implement firewalls are: 1. Proxy technology, which is a software module that transmits information from one side of the firewall to the other; 2. Multi-level filtering technology, which is to set up multi-layer filtering rules in the firewall; 3. NAT conversion technology can use NAT technology to transparently convert all internal addresses, so that the external network cannot understand the internal structure of the internal network; 4. Transparent access technology reduces the inherent security risks and error probability of system login.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

Firewall (English: Firewall) technology helps computer networks build a relatively isolated protective barrier between internal and external networks by organically combining various software and hardware devices for security management and screening. A technology to protect the security of user data and information.

The main function of firewall technology is to promptly discover and deal with security risks, data transmission and other issues that may exist when computer networks are running. The treatment measures include isolation and protection, and can also control various operations in computer network security. Implement recording and testing to ensure the security of computer network operations, protect the integrity of user data and information, and provide users with a better and safer computer network experience.

The main function of the firewall is to ensure network boundary security. The following technologies are mainly used to implement the firewall:

• Proxy technology:

  The proxy system is a kind of information transfer system A software module that travels from one side of the firewall to the other. The new generation firewall uses two proxy mechanisms, one for proxying connections from the internal network to the external network, and the other for proxying connections from the external network to the internal network. The former is solved by Network Address Translation (NAT) technology, and the latter is solved by non-confidential user-customized proxy or confidential proxy system technology.

• Multi-level filtering technology:

  is to set up multi-layer filtering rules in the firewall. At the network layer, packet filtering technology is used to intercept all fake IP source addresses and source routing packets; according to the filtering rules, the transport layer intercepts all inbound/outbound protocols and data packets; at the application layer, gateways such as FTP and SMTP are used to Monitor and control Internet services.

  In order to ensure the security and protection level of the system, the new generation firewall adopts three-level filtering measures, supplemented by identification methods. At the packet filtering level, all source routing packets and fake IP source addresses can be filtered out. At the application-level gateway level, various gateways such as FTP and SMTP can be used to control and monitor all common services provided by the Internet; at the circuit gateway level, transparent connections between internal hosts and external sites are realized, and strict access to services is implemented. control.

• Multi-port technology:

  has two or three independent network cards. The internal and external network cards can be connected in series between the internal network and the external network without IP conversion. During this time, another network card can be dedicated to the security of the server.

• NAT conversion technology:

  Use NAT technology to transparently translate all internal addresses, making the external network unable to understand the internal structure of the internal network, while allowing the internal network to Using its own customized IP address and private network, the firewall can record every host's traffic in detail, ensuring that each packet is sent to the correct address. In a network that also uses NAT, the connection to the external network can only be initiated by the internal network, which greatly improves the security of the internal network. Another obvious use of NAT is to solve the problem of IP address scarcity.

• Transparent access technology:

  The firewall utilizes transparent proxy system technology, thereby reducing the inherent security risks and error probability of system login.

• Anti-virus technology

  Firewall has anti-virus function. In the application of anti-virus technology, it mainly includes virus prevention, removal and detection. As for the anti-virus prevention function of the firewall, during the network construction process, the information data between the computer and the Internet is strictly controlled by installing the corresponding firewall, thereby forming a safe barrier to the computer external network and the internal network. Data enforcement protection. Computer networks are generally connected through the Internet and routers. Therefore, network protection needs to start from the backbone network and control the central resources of the backbone network to prevent illegal access to the server. In order to eliminate external Illegal intrusion steals information. The data connected to the computer connection port must be strictly checked by Ethernet and IP address. The stolen IP address will be discarded. At the same time, important information resources will be comprehensively recorded. Ensure that the information network of its computers has good security.

• Encryption Technology

  In the process of computer information transmission, firewalls can also effectively encrypt information. Through this encryption technology, relevant personnel can effectively encrypt the transmitted information, and the information password is mastered by both parties communicating the information. , the person receiving the information needs to decrypt the encrypted information before they can obtain the transmitted information data. In the application of firewall encryption technology, always pay attention to ensuring the security of information encryption processing. In the application of firewall technology, if you want to achieve safe transmission of information, you also need to verify the user's identity. After encryption, the transmission of information needs to authorize the user, and then the identity of the information receiver and sender needs to be verified. , thereby establishing a channel for secure information transmission to ensure that computer network information has good security during transmission. Criminals do not have the correct identity verification conditions, so they cannot intrude on computer network information.
  

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