What is Network Address Translation Technology?

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You can know the types of addresses (variable-length masks) based on the subnet mask, and the CIDR block based on the IP address. For example, the mask is a Class C address and the mask is a 24-bit roll. The network Li Zao address is a mask, a class C variable long subnet segment, a mask of 28 bits, a network address of 0, a broadcast address of 15, calculated by yourself, I haven't used it for a long time, and I generally use a subnet mask calculator.

Yes, IP and ** are one-to-one correspondence. When surfing the Internet, for the convenience of memory, ** is used instead of IP address.,In fact, using ** to access the network which is to use IP access.。 When you enter a **Internet access,first convert this** into an IP address,This conversion process is done through the DNS protocol on the computer。

IP addresses have a one-to-many relationship with domain names. An IP address can correspond to multiple domain names, but a domain name has only one IP address. IP addresses are made up of numbers, which is not easy to remember, so with a domain name, you can find the IP address by the domain name address.

Whenever a computer on an internal network wants to interconnect with an external network, the firewall hides its IP address and replaces it with the external IP address of the firewall. External users have no way of knowing the address of the internal network of the internal user, because it is hidden by the external IP address of the firewall. This operation of translating the IP address of the internal network is called Network Address Translation (NAT) technology.

Fix the problem that the private IP address cannot connect to the Internet. For example, internal users often use private IP addresses, but these private IP addresses cannot access the Internet, and this private IP address cannot access resources on the Internet. Therefore, the private IP address of the internal network must be converted to the public IP address of the external network.

Network address translation is a technique that translates one or more IP addresses into another IP or multiple addresses. Generally speaking, NAT technology mainly converts the internal private IP address of the host into an external legitimate IP address, so as to solve the lack of IP address resources and provide a technical means. The internal user uses the private IP address of the 10 network, and this IP becomes the public IP of 202 after the IP address is converted, and you can connect to the Internet.

There are three types of NAT: static NAT, pooled NAT, and port-level NAT.

Network Address Port Translation (NAPT) maps internal addresses to different ports of an IP address on an external network. It can hide small and medium-sized networks behind a legitimate IP address. NAPT differs from dynamic address NAT in that it maps an internal connection to a separate IP address in the external network, along with a port number selected by the NAT device to that address.

There are three ways to implement NAT, namely static nat, dynamic nat, and port multiplexing.

Static translation refers to the conversion of the private IP address of the internal network into a public IP address, the IP address pair is one-to-one and immutable, and a private IP address is only converted to a public IP address. With the help of static conversion, the external network can access certain specific devices in the internal network, such as servers.

When the private IP address of the internal network is converted into a public IP address, the IP address is indeterminate and random, and all the private IP addresses authorized to access the Internet can be randomly converted to any specified legal IP address. In other words, dynamic conversion can be performed as long as the office determines which internal addresses can be converted and which legal addresses can be used as external addresses. Dynamic transformations can use multiple sets of legitimate external addresses.

When the legitimate IP address provided by the ISP is slightly less than the number of computers inside the network. This can be done in the form of dynamic transformation.

Port address translation (PAT) refers to changing the source port of outgoing packets and performing port translation, i.e., port address translation (PAT).Port multiplexing mode is adopted. All hosts on the internal network can share a legitimate external IP address to achieve access to the Internet, so as to maximize the saving of IP address resources.

At the same time, it can hide all hosts in the network to effectively avoid attacks from the Internet. Therefore, port multiplexing is the most widely used method in the network.

Termination of Failure: Destination Translation NAT can be used to provide highly reliable services. If a system has a critical server accessed through a router, once the router detects that the server is down, it can transparently transfer the connection to a backup server using destination translation NAT.

Transparency: NAT can redirect HTTP connections to the Internet to a designated HTTP server to cache data and filter requests. Some Internet service providers use this technology to reduce bandwidth usage without having their customers configure their browsers to support ** connections Source address translation is address translation based on source addresses, which is mainly used for internal network access to the Internet, reducing the number of public addresses and hiding internal addresses.

For example, if the IP address is ,, the 3 PCs share the public IP address and Internet connection after the source address translation. Destination address translation can be divided into destination address mapping, destination port mapping, and server load balancing. Destination address translation is also known as reverse address translation or address mapping.

Destination address translation is a one-way mapping to a destination address, which is mainly used when an internal server provides services to the outside, and it differs from static address translation in that it is one-way. The outside can actively access the inside, but the inside cannot actively access the outside. In addition, you can use destination address translation to implement load balancing, that is, you can translate one destination address into multiple internal server addresses.

It is also possible to map different ports to different machines through port mapping.

For example, a PC on the Internet (by accessing the Internet address, through the destination address translation of the router, becomes a server accessing the intranet.