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of allowing or denying access, which largely improves the
security level of computer networks and avoids or reduces the
losses brought to users by data and information leakage.
3. Firewall technology
Firewall is a control device for two different networks to
realize mutual access, and it is an important security device
for network security to realize access control of private
network and public network according to the artificially
formulated control policy. The main role of firewall is to
shield the internal information, structure and operation of the
protected network, and to monitor and restrict the data flow
across the network. Firewall technology is an applied security
technology based on modern communication network
technology and information security technology, which is the
most recognized and widely used in the current network
security field. As shown in Figure 1
Figure 1. Diagram of the location of the firewall in the network
3.1. The main functions of firewall
The technology of firewall is very mature, and there are
many kinds of products, but the role is basically the same. The
overall function is to achieve isolation and security control
between two connected networks, and the main functions are
six points.
