Which command Linux can use to view a service and its ports, process numbers

2. Netstat/lsof
4. The netstat command is used to display statistics related to IP, TCP, UDP, and ICMP protocols, and is typically used to verify network connectivity across ports on the local computer.
6. -a displays a list of all valid connection information (including established connections, including those that listen for connection requests)
8. -N Shows all valid connections established
10. -T TCP protocol
12. -U UDP protocol
14. -L Query the program being monitored
16. -P shows the program identification code and program name using the socket
18. Example: Netstat-ntupl|grep processname
20. How do I query only tomcat connections?
22. Netstat-na|grep estab |grep |wc-l
24. Netstat-na|grep estab |grep 8080 |wc-l
26. Common Port Description:
28. Port: 21
30. Service: FTP server open port for uploading, downloading.
32. Port: 22
34. Service: SSH
36. PORT: 80
38. Service: HTTP for web browsing
40. PORT: 389
42. Services: LDAP ILS Lightweight Directory Access Protocol and netmeetinginternet Locator Server
44. Port: 443
46. Service: A Web browsing port can provide encryption and another HTTP transmission over a secure port
48. Port: 8080
50. Service: Proxy port
52. Open the terminal and execute the following command to see the port status of each process:
56. # ps-ef|wc-l //view total number of processes running in the background
58. # Ps-fu CSVN //view CSVN process
62. # NETSTAT-LNTP //See which ports are open
64. # Netstat-r //This option can display information about the routing table
66. # netstat-a //This option displays a list of all valid connection information
68. # netstat-an|grep 8080
70. # Netstat-na|grep-i Listen //Can see the current system listening port number
72. # Netstat-antup //View the established connection process, the occupied port.
74. netstat-anp|grep1487
76. lsof-i:1487
78. See which processes open the specified port 1487
82. The shutdown port is actually shutting down its corresponding service, such as 80 port is httpd shutdown 80 port can be implemented by shutting down the httpd service
84. Each port has a daemon, kill the daemon.
86. The host's port is divided into a listening port and a randomly available premium port
88. Listening Port: The listening port is the service that the host is powered on, and this service enables a port on the Linux system to listen for client requests
90. A randomly available premium port:
92. Linux to request a service from a host, the Linux host needs to enable a port to connect externally Linux randomly connects to a port that is not in use and has a number greater than 1024
94. Only the root user can open port 1-1024 to indicate root privileges
96. Netstat-n Show Connection Status
98. NETSTAT-TL displays the name of the service that is currently listening
100. Linux is a tool to list the open files of the current system, and in the Linux environment, everything is in the form of files.
102. Lsof output information to display system open files by default show all files open by all processes
104. lsof filename Displays all processes that open the specified file
106. Lsof-c string Displays all open files for the process containing the specified characters in the command column
108. Lsof-u Username Displays the files that are open by the user process
110. Lsof-g GID shows the process of attribution to GID
112. Lsof-i Show eligible process conditions
114. Lsof-d the process that displays the specified file descriptor
116. Lsof-a indicates that two parameters must be met before the results are displayed
118. Example: lsof-i:1487
120. To view files whose file type is txt opened by the root user process:
122. Lsof-a-u root-d txt
124. Lsof Use Instances
126. 1. Find using the file system
128. When uninstalling the file system, an error occurs if there are any open files in the file system. Lsof can be used to find out which processes are using the currently uninstalled file system
130. # lsof/gtes11/
132. COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
134. Bash 4208 root cwd DIR 3,1 40962/gtes11/
136. Vim 4230 root CWD DIR 3,1 40962/gtes11/
138. 2. Recover deleted files
140. When a Linux computer is compromised, it is common for log files to be deleted and administrative errors to cause accidental deletion of important files.
142. When a process opens a file, it remains on disk as long as the process remains open for that file, even if it is deleted. This means that the process does not know that the file has been deleted, and in the/proc directory, it contains various files that reflect the kernel and the process tree.
144. When a file in the system is accidentally deleted, as long as there are processes in the system that are accessing the file, you can recover the file from the/proc directory by lsof
146. Use lsof to see if there are currently processes open/var/logmessages files
148. # lsof |grep/var/log/messages syslogd 1283 root 2w REG 3,3 5381017 1773647/var/log/messages (deleted) from/proc/128 3/FD/2
150. This method of recovering deleted files is useful for many applications, especially log files and databases

Which command Linux can use to view a service and its ports, process numbers