1. 环境
CentOS 7.5 ，本人选择最完整版安装（workstation选项）
2. 关闭FireWall和SELinux
2.1 FireWall
使用systemctl status firewalld查看防火墙的状态，如下（默认开启）
[558idc@localhost ~]$ systemctl status firewalld
// 防火墙状态
● firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
Active: active (running) since 二 2018-11-13 14:40:53 CST; 11min ago
Docs: man:firewalld(1)
Main PID: 821 (firewalld)
Tasks: 2
CGroup: /system.slice/firewalld.service
└─821 /usr/bin/Python -Es /usr/sbin/firewalld --nofork --nopid
11月 13 14:40:51 localhost.localdomain systemd[1]: Starting firewalld - dyna...
11月 13 14:40:53 localhost.localdomain systemd[1]: Started firewalld - dynam...
Hint: Some lines were ellipsized, use -l to show in full.
如果你需要使用FireWall服务（正式环境下），则需要修改它的配置，因为在默认情况下，它会拦截大多数服务请求。具体可以参考配置firewalld服务的基本操作和设置。
如果由于某些原因（比如本文只是需要Linux服务器来搭建某些服务，不想控制防火墙只开放某些端口）等而不需要FireWall服务，则可以像下面那样停止并禁用它。
// 关闭服务
[558idc@localhost ~]$ systemctl stop firewalld
// 关闭开机自动开启FireWall服务
[558idc@localhost ~]$ systemctl disable firewalld
Removed symlink /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed symlink /etc/systemd/system/dbus-org.Fedoraproject.FirewallD1.service.
2.2 关闭SELinux
可以用getenforce 查看SELinux的状态，如下（默认开启）
[558idc@localhost ~]$ getenforce
//开启状态
Enforcing
同上，如果你想使用SELinux也可以。但是本人不想那么麻烦，所以把SELinux也关闭了。
[558idc@localhost ~]$ sudo nano /etc/selinux/config
# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced.
# permissive - SELinux prints warnings instead of enforcing.
# disabled - No SELinux policy is loaded.
// 这里改变为disabled
SELINUX=disabled
# SELINUXTYPE= can take one of three two values:
# targeted - Targeted processes are protected,
# minimum - Modification of targeted policy. Only selected processes are protected.
# mls - Multi Level Security protection.
SELINUXTYPE=targeted
// 重启使配置生效
[558idc@localhost ~]# reboot
3. 一点错误
使用root权限用户操作