[Linux environment] centos7 Failed to start iptables.service: Unit not found firewall

Contents of this article

I. Introduction

Second, the command to manage the firewall

2.1, turn on the firewall

2.1.1 First check the firewall status

2.1.2 Turn on the firewall

2.1.3 Set auto start after power-on

2.1.4 Restart the firewall

2.1.5 Check whether the firewall setting is successful after booting up

2.2, open a specific port

2.2.1 Add port

2.2.2 Reload

2.2.3 View

2.2.4 Delete

2.2.5 Turn off the firewall

2.2.6 View all open ports

2.2.7 View service monitoring

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I. Introduction

In Centos 7.x, the firewall is managed by firewalld. In the past, the firewall was turned off for convenience. Now that the projects are more important and afraid of being attacked, the firewall needs to be turned on for security. Next, let’s introduce the commonly used ones. command.

Second, the command to manage the firewall

There are many commands for managing firewalls, here are a few commonly used ones.

2.1, turn on the firewall

2.1.1 First check the firewall status

Command: firewall-cmd --state

The open state is as follows:

The closed state is as follows:

2.1.2 Turn on the firewall

命令：systemctl start firewalld.service

2.1.3 Set auto start after power-on

命令：systemctl enable firewalld.service

2.1.4 Restart the firewall

命令：systemctl restart firewalld.service

2.1.5 Check whether the firewall setting is successful after booting up

命令：systemctl is-enabled firewalld.service;echo $?

As shown in the figure below, it means self-starting is successful

 

The above are the steps to open the firewall

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2.2, open a specific port

After turning on the firewall, some of our services will not be accessible because the relevant ports of the service are not opened. Here is an example of opening port 80/3306

2.2.1 Add port

Command: firewall-cmd --zone=public --add-port=80/tcp --permanent (--permanent takes effect permanently, and it becomes invalid after restart without this parameter)

If you want to add another port number, please repeat the command after modifying the 80 port number, such as: firewall-cmd --zone=public --add-port=3306/tcp --permanent

Add ports in batch (add all ports between 1000 and 2000)

命令：firewall-cmd --zone=public --add-port=1000-2000/tcp --permanent

Command meaning: --zone #scope--add-port=80/tcp #add port, format is: port/communication protocol--permanent #permanent effect, invalid after restart without this parameter 

As shown in the figure below, it means the addition is successful:

 

2.2.2 Reload

Command: firewall-cmd --reload

2.2.3 View

命令：firewall-cmd --zone=public --query-port=80/tcp

2.2.4 Delete

命令：firewall-cmd --zone=public --remove-port=80/tcp --permanent

2.2.5 Turn off the firewall

命令：systemctl stop firewalld.service

2.2.6 View all open ports

Command: firewall-cmd --list-ports

 

2.2.7 View service monitoring

Command: netstat -ntlp

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end!