NAT vs. NAPT. Difference 15

NAT: Network Address Translation. napt:

Network address port translation. They are both address translations, the difference is that NAT is NAT is a one-to-one translation, and NAPT is a many-to-one translation. In layman's terms, NAT is an internal address that translates into an external address for communication, while NAPT is a communication between multiple internal addresses using the same address and different ports.

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NAT (Network Address Translation) was proposed in 1994 and can be used when some hosts in a private network have been assigned a local IP address (i.e., a dedicated address that is only used in the private network), but now want to communicate with the host on the Internet (without encryption).

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

1. Static conversion 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.

2. Dynamic conversion refers to the conversion of the private IP address of the internal network into a public IP address, the IP address is uncertain and random, and all the private IP addresses authorized to access the Internet can be randomly converted into any specified legal IP address. That is, dynamic translation can occur as long as you specify which internal addresses can be translated, and which legitimate 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.

3. Port address translation (PAT) refers to changing the source port of outgoing packets and performing port translation, that is, port address translation (PAT), using port multiplexing.

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 inside the network to effectively avoid attacks from the Internet. Therefore, port multiplexing is the most widely used method in the network.

1. Different application scenarios.

Source NAT (commonly referred to as NAT): Used in the case of a local area network and multiple public IPs.

Destination NAT (commonly known as port mapping): It is used to set up external services (web services) in a local area network. Public IP addresses can provide N (port number) services.

2. Different conversion paths.

Source NAT: Conversion from a private network to a public network (the private network accesses the public network, and the destination IP address remains unchanged, and only the source IP address is converted).

3. Different functions.

The source NAT converts the IP address of the intranet host into the Internet IP of the gateway, enabling the intranet host to access the Internet.

The purpose of NAT is to map the Internet port of the gateway to the intranet IP on the gateway NAT server.

NAT (Network Address Translation) refers to Network Address Translation, 1994. The NAT method can be used when some hosts in a private network have already been assigned a local IP address (i.e., a dedicated address that is only used in the private network), but want to communicate with the host on the Internet (without encryption).

How it works. With the help of NAT, private (reserved) addresses"Interior"When the network sends data packets through the router, the private address is converted into a legitimate IP address, and a LAN only needs to use a small number of IP addresses (or even one) to realize the communication needs of all computers in the private address network with the Internet.

NAT automatically modifies the source and destination IP addresses of IP packets, and the IP address verification is performed automatically during NAT processing. Some applications embed the source IP address into the data portion of the IP packet, so you need to modify the data portion of the packet to match the source IP address in the IP header. Otherwise, applications that embed IP addresses in the packet data section will not work properly.

The full name of NAT is Network Address Translation, which refers to and Bi is Network Address Translation, which was proposed in the 90s of the 20th century. It is mainly a network transfer method, if some hosts in the private network have been assigned a fixed Lu and local IP address, but want to communicate with other hosts on the Internet, the NAT method will be used.

NAT can not only solve the IP address problem of other hosts that the host wants to contact, but also have the function of defense, avoid attacks from other networks, and hide their own network information.