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When installing services such as nginx,mysql,tomcat, we will encounter that the ports we need to use are inexplicably occupied. Here's how to solve this problem.

When it comes to ports, firewalls have to be mentioned, and this article will briefly describe how to configure firewall development ports.

Various ways for Linux to check the situation of ports

The mapping of all ports is found in the / etc/services file

The Linux port is briefly introduced. The port number ranges from 0 to 65536. The purpose of each numbered end is as follows:

0-1023: well-known port, binding to common services (FTP,SSH)

1024-49151: register port for binding to some services

49152-65535: dynamic or private ports that can be used for any network connection

Ports are divided into TCP and UDP transport protocols.

Linux View Port status command

You can check the port situation with the following command. Click the command to adjust the usage details of each command:

Nmap command, port scan using

Netstat inspection development port

Lsof checks the port descriptor

# check the port nmap 127.0.0.00 bound to this machine. Check port 3306 netstat-anlp | grep 330 checks the 3306 interface lsof-iRanger 3306.

Linux release Occupy Port solution

The resolution steps are as follows:

Find the processes that occupy the port

Kill the process.

Use the following command:

# can be written as a command

Netstat-anp | grep 8080 | awk'{print $7}'| awk-F'/'{print $1}'| xargs kill-s 9

Each command has the following meanings:

Netstat-anp shows all network usage and shows the usage program

Grep 8080 matches the record of port 8080 (may contain 18080)

Awk'{print $7} 'outputs the seventh column of processes in the following form: 18989/nginx

Awk-F'/'{print $1} 'intercepts process PID:18989

Xargs kill-s 9 kills the process using the output of the previous command as an argument

Step-by-step solution to release occupied ports

Query whether the port is occupied

For example, if you need to query whether port 8080 is occupied, you can use the following command

Netstat-an | grep 8080

Query the processes that occupy the port

You can use the lsof command to view

Lsof-iPUR 8080

You can also use netstat and grep to view

Netstat-anp | grep 8080

The last line of the command is the PID and name of the process that occupies port 8080.

Kill the process that occupies the port

You can use the kill command to directly kill the process found in the previous step.

Kill-9 19664

Linux Firewall release Port

Linux Firewall on and off

The firewall described below is iptable and does not apply to firewalld.

Turn on the firewall (permanently effective after reboot): chkconfig iptables on

Turn off the firewall (permanently effective after reboot): chkconfig iptables off

Enable the firewall (effective immediately, invalidate after restart): service iptables start

Turn off the firewall (effective immediately, invalid after restart): service iptables stop

Restart the firewall: service iptables restart

Linux View Firewall status

You can view it using the following command:

/ etc/init.d/iptables status# or iptables statusiptables-L # can also be viewed directly in the configuration file vim / etc/sysconfig/iptables

Linux opens a port in the firewall

For example, to open port 8080, you can use the following command:

Iptables-An INPUT-p tcp-- dport 8080-j ACCEPT# also needs to restart the service service iptables restart#. You can also edit the configuration file vim / etc/sysconfig/iptables# directly and add a line at the end of the file. Develop all ports between 8080 and 8181: iptables-An INPUT-p tcp-- dport 8080 dport 8181-j ACCEPT.

Among them

The-A parameter is treated as adding a rule

-p specifies what the protocol is, our commonly used tcp protocol, of course, there is also udp

-dport is the target port. When data enters the server from the outside, it is the target port.

-if sport data is sent out of the server, it will be used for the data source port

-j specifies ACCEPT-receive or DROP does not receive

The above is all the contents of the article "Linux forced release of occupied ports and Linux firewall port opening example". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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