Introduction to Linux Network Stack
In the Linux operating system, the network stack is useful to communicate the application with the physical network devices. The network stack is divided into multiple layers. There are different network layers. The same different roles are playing their individual role. Generally, all the operating system supports the network stack role. With the help of the network, we are able to use or connect the different network devices like routers, modems, cable modems, ISDN Mode, Wi-Fi devices, Ethernet cards, Broadband connector, Token Ring cards, etc. While communicating with different devices, the physical layer comes in the picture. It is representing the data in terms of bit format and communicates the different devices physical layer in bit format only.
Syntax of the Linux Network Stack
Network Command/Utility [ OPTION ] ... [ FILE / IP / INPUT FILE / …]
- Network Command/Utility : As per the requirement and use, we can use the “Network Command or Utility” keyword in the syntax or command. It will take different arguments like options, input file, IP address, different compatible options. As per the provided arguments, it will provide the network-related information on the screen.
- OPTIONS : We can provide the different flags as the option that is compatible with the “Network Command or Utility”.
- FILE / IP / INPUT FILE: As per the condition or requirement, we can provide the different options or arguments to the “Network Command/Utility”.
How Linux Network Stack Works?
Linux is a multi-user support operating system and supports all the network stack functionality. While communicating with the network, it will follow the two ways of communication. First, the end-user or the client will request access or the file request. Second, as per the necessary access or request type, the request will full fill and set the acknowledgment to the end-user or the client. In this network process number of different network-layer comes into the picture.
Below is the list of layers that come into the picture.
- Application Layer
- System call Interface
- Protocol Agnostic Interface
- Network Protocol
- Device Agnostic Interface
- Device Drivers
- Physical Hardware
- Application Layer: It comes to the TCP as well as the UDP protocols. On the application layer, applications like different browser or other application which accesses the Internet works in this layer. Any application or jobs that are accessing the internet then it will consider in the application layer. When we are opening or closing any file on the network level with the help of any tool or application, it will relay on the same application.
- System call Interface: The SCI stands for System Call Interface. The call will happen when the application layer to the kernel level. Let’s continue with the sample example of editing any image. We need to request for the file from a network or remote location. In the same case, we are sending the read request to the kernel for the editing of the image.
- Protocol Agnostic Interface: In the Protocol Agnostic Interface, it will create the socket. The same created socket is responsible for the two types of communication i.e., talking or listening. Each socket has its own ID. The same id will further be used specifically for an application.
- Network Protocol: The Network Protocol is responsible for sending and receiving data. In other words, we can say that how the data is sent or received. The network layers controls the send and receive information across the network. Specifically, in-network layer work on the router level or router table. This layer is also providing the network routing information.
- Device Agnostic Interface: The Device Agnostic Interface is used to communicate or connect the data from or to the Kernel level and the network drivers or device drivers.
- Device Drivers: The Device Drivers Layer, in this layer the real device driver of the network device will use. This layer is allowed preparing the data for the transmission. Once the data is ready for the transmission. It will transmit the data over the network device.
- Physical Hardware: The Physical Hardware layer is also known as the hardware layer or the network hardware. On the same layer, the data packets will transmit or received from the network medium. The network medium will be cable or wireless.
Examples to Implement Linux Network Stack
Lets us discuss the examples of Linux network stack.
Linux Network Stack: arpwatch
In the Linux network stack, the arpwatch is a utility to observe the Ethernet traffic activity. It will also observe the changing IP and MAC Address.
arpwatch -i enp0s3
tail -f /var/log/messages
As per the above command, we are using the network utility i.e. arpwatch. It is monitoring the activity on the “enp0s3” network interphase and if the arpwatch utility finds any changes in the interphase level. It will mark it in “/var/log/messages” file.
Linux Network Stack – ifstat
With the help of ifstat utility, we are able to get detail information of the network interfaces.
In the ifstat command, we are getting the detail information of the network interphase i.e. “enp0s3”.
Linux Network Stack – nload
With the help of nload utility, we are able to get detail information about the network traffic.
As per the above command, we are able to get the network load or traffic information on the system.
Linux Network Stack – hping
In Linux, we are having the functionality to analyse the TCP and the IP things.
hping3 -S 192.168.56.60 -p 80
As per the above command, we are analysing the TCP port 80 on the IP address 192.168.56.60.
We have seen the uncut concept of “Linux Network Stack” with the proper example, explanation, and command with different outputs. It is very important to understand how the network flow is and which different layers comes in the picture while data is flowing in between the different application levels or job level.
This is a guide to Linux Network Stack. Here we discuss an introduction to Linux Network Stack, syntax, How Linux Network Stack Works? with examples. You can also go through our other related articles to learn more –