Introduction: In the Linux system, network connection and status are things that we often need to understand and monitor in our daily work. As a powerful network tool, the netstat command can provide information about network connections, routing tables, and network interfaces to help us better manage and diagnose network problems. This blog will analyze the common parameters and usage of the netstat command in an easy-to-understand manner, with sample codes and reference links to help you understand and use the netstat command in depth.
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1. Introduction to netstat command
The netstat command is a common network tool in the Linux system, which is used to display related information such as network connections, routing tables, and network interfaces. It helps us monitor network activity, diagnose network problems, and view the status of network connections.
2. Display all network connections
Use the netstat -a command to display all network connections, including TCP and UDP connections. The sample code is as follows:
netstat -a
This command will list the local IP address and port, the remote IP address and port, and the connection status (such as ESTABLISHED, LISTENING, etc.). Through this command, we can learn about all network connections on the current system.
Third, view the connection of a specific protocol
Sometimes we only care about connections of a specific protocol, such as TCP or UDP. The netstat command provides corresponding parameters to filter the connection information of a specific protocol.
- View TCP connections: netstat -t
- View UDP connection: netstat -u
sample code is as follows:
netstat -t
netstat -u
Through these commands, we can only display the network connections of the required protocol type, which is convenient for us to understand and manage the network more precisely.
4. Check the port of listening status
In servers, we often need to know which ports are listening for connections. Use the netstat -l command to display port information in the listening state. The sample code is as follows:
netstat -l
This command will list the ports that are listening, including the local IP address, port number, and listening status. This is useful for determining whether a server is listening on a specific port normally.
5. Display process-related connections
Sometimes we want to know the process information associated behind each network connection in order to quickly locate the problem. Use the netstat -p command to display the process ID and process name associated with each network connection. The sample code is as follows:
netstat -p
Through this command, we can easily determine the process using a specific network connection, and conduct further analysis and troubleshooting.
6. Display the routing table of the system
The routing table records how the data packets are transferred in the network
Rules and paths for sending. Use the netstat -r command to display the routing table information of the system. The sample code is as follows:
netstat -r
This command will display the target network, gateway, interface and other relevant information. By understanding the routing table, we can better understand the relationship between the transmission path of the data packet and the network.
7. Other common parameters and usage
The netstat command also has some other commonly used parameters and usage:
- netstat -c: Continuously display the network connection status in real time, which is convenient for real-time monitoring of network activities.
- netstat -i: Display the network interface information of the system, including interface name, IP address, MAC address, etc.
- netstat -s: Display network statistics, such as the number of packets sent and received, the number of errors, etc.
8. Summary
The netstat command is a powerful network tool in the Linux system. Through it, we can easily view information such as network connections, routing tables, and interfaces, and help us monitor network activities, diagnose problems, and manage network status. This blog briefly introduces the common parameters and usage of the netstat command, and provides sample codes and reference links, hoping to help readers better understand and apply the netstat command.
Reference link:
- Official documentation for the netstat command
- Detailed introduction to the netstat command
- Detailed explanation of Linux netstat command
- Netstat command example and detailed usage
The above is a detailed analysis of the netstat command under Linux.