Differences and precautions in building web servers on CentOS 6 and CentOS 7

Differences and precautions in building web servers on CentOS 6 and CentOS 7

With the rapid development of the Internet, web servers, as the infrastructure for hosting websites and applications, are becoming more and more important. CentOS is a widely used Linux distribution and one of the common choices for building web servers. However, there are some differences and precautions that need to be paid attention to when setting up a web server on CentOS 6 and CentOS 7.

1. Changes in installation methods
   CentOS 6 uses the yum command to install and manage software packages. In CentOS 7, a new package management tool dnf was introduced, but yum can still be used. Keep in mind that it is recommended to use the new dnf instead of yum for package installation and updates.
2. Changes in firewall management rules
   In CentOS 6, iptables is used as the firewall management tool by default. In CentOS 7, a new firewall management tool firewalld was introduced. The usage and syntax of the two tools differ. The following is an example iptables rule:

# 允许SSH连接
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
# 允许HTTP连接
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
# 允许HTTPS连接
iptables -A INPUT -p tcp --dport 443 -j ACCEPT

And the following is an example firewalld rule:

# 允许SSH连接
firewall-cmd --add-service=ssh --permanent
# 允许HTTP连接
firewall-cmd --add-service=http --permanent
# 允许HTTPS连接
firewall-cmd --add-service=https --permanent
firewall-cmd --reload

3. Changes in the default web server
   CentOS 6 uses Apache by default HTTP Server acts as a web server. In CentOS 7, Nginx is used as the web server by default. If you want to use Apache on CentOS 7, you can install it with the following command:

dnf install httpd
systemctl enable httpd
systemctl start httpd

4. Changes in network configuration
   In CentOS 6, the network configuration file is usually located in /etc/ In the sysconfig/network-scripts directory. In CentOS 7, the network configuration file is migrated to the /etc/sysconfig/network-scripts/ifcfg- directory, where represents the name of the network interface. The following is an example ifcfg-eth0 configuration file:

TYPE=Ethernet
BOOTPROTO=static
DEFROUTE=yes
PEERDNS=yes
PEERROUTES=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPV6_FAILURE_FATAL=no
NAME=eth0
UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
DEVICE=eth0
ONBOOT=yes
IPADDR=192.168.1.100
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
DNS1=8.8.8.8

5. Changes in SELinux
   SELinux is the mandatory access control (Mandatory Access Control) tool enabled by default in CentOS. In CentOS 6, the status of SELinux can be viewed and changed using the getenforce command. In CentOS 7, the new command sestatus is used to view the status of SELinux, and setenforce is used to change the status of SELinux.

# 查看SELinux状态
sestatus
# 关闭SELinux
setenforce 0
# 开启SELinux
setenforce 1

It should be noted that turning off SELinux may reduce the security of the system. Therefore, when building a web server, it is recommended to turn off SELinux only in the test environment.

Summary:
CentOS 6 and CentOS 7 have some differences and precautions that need to be paid attention to when building a web server. There are some changes in the installation method, firewall management rules, default web server, network configuration and SELinux. Understanding these differences and precautions can help you better build and manage web servers and ensure system stability and security.

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