How to check ports in Linux

Linux methods to view ports include using the netstat command, using the ss command, using the lsof command, using the nmap command, using the iptables command, etc. Detailed introduction: 1. Use the netstat command. The netstat command is used to display information such as network connections, routing tables, and network interfaces. By using different parameters, you can view different port information; 2. Use the ss command, which is a substitute for the netstat command. , which can display network connection information more quickly; 3. Use the lsof command, etc.

#In Linux systems, there are many ways to view the currently open ports. The following are several commonly used methods:

1. Use the netstat command:

The netstat command is used to display information such as network connections, routing tables, and network interfaces. By using different parameters, you can view different port information. For example, use the following command to view all listening ports:

   netstat -tuln

Parameter description:

-t: Display TCP connection information

-u: Display UDP connection information

-l: Only display connections in listening status

-n: Display ports and IP addresses in numerical form

2. Use the ss command:

ss command is a replacement for the netstat command and can display network connection information more quickly. Use the following command to view all listening ports:

   ss -tuln

Parameter description:

-t: Display TCP connection information

-u: Display UDP connection information

-l: Only display connections in listening status

-n: Display ports and IP addresses in numerical form

3. Use the lsof command:

Use the lsof command Used to display currently open files and process information, and can also be used to view network port information. Use the following command to view all listening ports:

   lsof -i :端口号

For example, to view the listening status of port number 80, you can use the following command:

   lsof -i :80

4. Use the nmap command:

The nmap command is a network detection and security scanning tool that can also be used to view open ports. Use the following command to scan the open ports of the specified host:

   nmap IP地址

For example, to scan the open ports of the host with the IP address 192.168.0.1, you can use the following command:

   nmap 192.168.0.1

5. Use iptables Command:

The iptables command is a tool used to configure and manage firewall rules in Linux systems. It can also be used to view open ports. Use the following command to view the ports open in the current firewall rules:

   iptables -L -n

The above are several commonly used methods to view port information in Linux systems. According to different needs and usage scenarios, you can choose a method that suits you to view port information. It should be noted that viewing port information requires sufficient permissions, and you may need to use the sudo command or execute it as the root user.

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