Shulou(Shulou.com)05/31 Report--

This article mainly explains "what is the role of lo in linux". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "what is the role of lo in linux"?

In linux, lo is the abbreviation of local, which refers to the local loopback interface, which can be used to send and receive data inside the system. The main function is to detect the network configuration of the machine and provide resources on the server that some applications need to call when they are running.

The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

What is lo in linux

Lo: the abbreviation for local, which generally refers to the local loopback interface.

The function of lo interface

A local process initiates a connection to a port (8085) of a local daemon listening intranet IP address (eth2: 10.1.1.1). At this time, the packet cannot be caught on the eth2, but it is caught on the lo, indicating that the local loopback interface lo is used, while the IP address of the network layer is the intranet IP address.

Lo is actually a virtual loopback interface of the system, and its IP address is 127.0.0.1. Using this interface, you can send and receive data within the system, so generally we use: ping 127.0.0.1 can ping, because this is actually the establishment of a connection within the system.

127.0.0.1, commonly referred to as a local loopback address (Loop back address), does not belong to any classful address class. It represents the local virtual interface of the device, so it is considered by default to be an interface that will never go down. It is usually possible to ping this local loopback address before installing the network card. It is generally used to check whether the local network protocol and basic data interface are normal.

It has two main functions:

One is to test the network configuration of the machine. The ability to PING 127.0.0.1 indicates that there is no problem with the installation of the network card and IP protocol of the machine.

Another function is that some SERVER/CLIENT applications need to call resources on the server at run time

1. Naming of network interfaces

There is no naming convention here, but the definition of network interface names is generally meaningful. For example:

Eth0: shorthand for ethernet, commonly used on Ethernet interfaces.

Wifi0:wifi is a wireless local area network, so wifi0 generally refers to a wireless network interface.

Ath0: the abbreviation of Atheros, which generally refers to the wireless network interface contained in the Atheros chip.

Lo: the abbreviation for local, which generally refers to the local loopback interface.

two。 How the network interface works

The network interface is the basic device used to send and receive data packets.

All the network interfaces in the system form a chain structure, and the application layer program is called by name when it is used.

Each network interface corresponds to a struct net_device structure in the linux system, including name,mac,mask,mtu. information.

Each hardware network card (a MAC) corresponds to a network interface, and its work is completely controlled by the corresponding driver.

3. Virtual network interface

Virtual network interface has a wide range of applications. The most famous is "lo", almost every linux system has this interface.

The virtual network interface does not really receive and send packets from the outside world, but receives and sends packets within the system, so the virtual network interface does not need a driver.

The virtual network interface and the real network interface are consistent in use.

4. Creation of network interface

The network interface of the hardware network card is created by the driver. The virtual network interface is created by the system or through the application layer program.

The function to create a network interface in the driver is: register_netdev (struct net_device *) or register_netdevice (struct net_device *).

The difference between the two functions is: register_netdev (…) An interface with the name "eth" is automatically generated, while register_netdevice (...) The interface name needs to be specified in advance. In fact, register_netdev (…) Also by calling register_netdevice (...) It came true.

At this point, I believe you have a deeper understanding of "what is the role of lo in linux". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.