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A Paper to understand what is a firewall
1.The origin of the firewall
The term “firewall” originated in construction to isolate fires and stop them from spreading from one area to another. In the field of communication, firewalls are often used to isolate two networks in a logical sense. Of course, this kind of isolation is clever, isolating the spread of “fire”, and ensure that “people” through the wall.
Here, “fire” refers to various attacks on the network, and “human” refers to normal communication packets.
Defined in communication language, firewalls are mainly used to protect one network area from network attacks and network intrusions from another network area.
Because of its isolation and defense properties, it can be flexibly applied to network boundaries and subnet isolation, such as the egress of an enterprise network, subnet isolation within a large network, and data center boundaries.
2 Differences between firewalls and switch routers
Routers are used to connect different networks and ensure that packets are forwarded to the destination through routing protocols. The switch is usually used to build the LAN, as an important hub of the LAN communication, through layer 2 / layer 3 exchange fast forwarding packets;
The firewall is mainly deployed at the network boundary to control the access behavior in and out of the network. Security protection is its core feature. The essence of router and switch is forwarding, the essence of firewall is control.
3. Firewall security zone
1. Security Zone, or Zone for short
A Zone is a local logical security Zone.
A Zone is a network to which one or more interfaces are connected.
2. Functions of Zone:
Security policies are implemented based on security zones.
Data flows within a security zone do not have security risks and do not require any security policies.
The security check of the device is triggered only when data flows occur between security zones and corresponding security policies are implemented.
On a firewall, all network devices connected to the same interface must reside in the same security zone. A security zone can contain the networks connected to multiple interfaces.
3. Default security zone
Untrusted zone Untrust
Demilitarized zone DMZ
Trusted Area Trust
Local Area Local
A Paper to understand what is a firewall
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