Common pitfalls in building web servers on CentOS and how to avoid them

Common traps in building web servers on CentOS and how to avoid them

Abstract: In the process of building a web server, it is easy to encounter some traps. This article will introduce some common pitfalls and provide ways to avoid them. At the same time, some practical code examples will also be given to help readers better understand and practice.

1. Trap: Improperly configured firewall

In the process of building a web server, it is very important to configure the firewall correctly. If the firewall is not configured correctly, the server may be attacked or even hacked.

Avoidance method:
Use the iptables command to configure the firewall. The following is an example configuration that allows HTTP and HTTPS traffic through the firewall:

sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 443 -j ACCEPT
sudo iptables -A INPUT -j DROP

2. Trap: SELinux is not configured correctly

SELinux is a security mechanism in CentOS that works Locally limit the permissions of the process and improve the security of the server. However, when setting up a web server, if SELinux is not configured correctly, it may result in the inability to access the web page normally.

Avoidance method:
First, you can use the following command to check the status of SELinux:

sestatus

If the SELinux status is Enforced, it means that SELinux is performing strict security checks. SELinux can be disabled by modifying the configuration file /etc/selinux/config:

sudo vi /etc/selinux/config

Modify the value of SELINUX to disabled, save and exit. Then, restart the server to make the configuration take effect:

sudo reboot

3. Trap: Virtual host is not configured correctly

When building a web server, if the virtual host is not configured correctly, it may cause Several websites cannot be accessed correctly. This is because the Apache server only allows access to one website by default.

Avoidance method:
Add the configuration of the virtual host in the Apache configuration file. The following is an example configuration, adding two virtual hosts example.com and example2.com:

<VirtualHost *:80>
    ServerName example.com
    DocumentRoot /var/www/example.com
</VirtualHost>

<VirtualHost *:80>
    ServerName example2.com
    DocumentRoot /var/www/example2.com
</VirtualHost>

4. Trap: File permissions are not configured correctly

When setting up the web server , if file permissions are not configured correctly, it may result in the inability to access web pages properly. This is because the server needs to access and execute various files and cannot function properly without the correct permissions.

Method to avoid:
Use the following command to modify the permissions of the file:

sudo chown -R apache:apache /var/www/example.com
sudo chmod -R 755 /var/www/example.com

The above command will change the owner and group of all files under /var/www/example.com for apache and set permissions to 755.

Conclusion:
In the process of building a web server, we need to pay attention to some common traps and take corresponding avoidance methods. Configuring firewalls, SELinux, virtual hosts, and file permissions are some important aspects of setting up a web server. I hope that the avoidance methods and code examples provided in this article can help readers better build their own web servers.

Extended reading:

• [CentOS official documentation](https://www.centos.org/docs/)
• [Apache official website](https ://httpd.apache.org/)

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