一、防火墙

CentOS7默认用firewall作为防火墙，不同于CentOS6用iptables

查看防火墙状态

firewall-cmd --state

启动防火墙

systemctl start firewalld.service

关闭防火墙

systemctl stop firewalld.service

开机启动

systemctl enable firewalld.service #开机自启 systemctl disable firewalld.service #开机不自启

重新加载配置

firewall-cmd --reload

查看开放端口

firewall-cmd --zone=public --list-ports

添加开放端口

firewall-cmd --zone=public --add-port=80/tcp --permanent

移除开放端口

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

二、设置主机名

方法一、$ hostnamectl set-hostname node01 永久有效 方法二、$ vim /etc/hostname  加入主机名node01 永久有效 方法三、$ hostname node01 临时有效，重启失效

三、自带jdk

装jdk时候发现系统有了个openjdk，上网查看才知道centos7一般自带的jdk，不是oracle官方的，所以要把它卸载掉

[root@localhost home]# java -version openjdk version "1.8.0_161" OpenJDK Runtime Environment (build 1.8.0_161-b14) OpenJDK 64-Bit Server VM (build 25.161-b14, mixed mode)

首先查看具体有哪些 jdk

[root@localhost home]# rpm -qa | grep java python-javapackages-3.4.1-11.el7.noarch java-1.8.0-openjdk-headless-1.8.0.161-2.b14.el7.x86_64 tzdata-java-2018c-1.el7.noarch java-1.7.0-openjdk-1.7.0.171-2.6.13.2.el7.x86_64 java-1.8.0-openjdk-1.8.0.161-2.b14.el7.x86_64 javapackages-tools-3.4.1-11.el7.noarch java-1.7.0-openjdk-headless-1.7.0.171-2.6.13.2.el7.x86_64

看到openjdk 1.7、1.8都有，接下来把他们卸载掉，也可以按文件名逐个卸载

[root@localhost home]# rpm -e --nodeps java*openjdk*

从新查看是否卸载

[root@localhost home]# rpm -qa | grep java python-javapackages-3.4.1-11.el7.noarch tzdata-java-2018c-1.el7.noarch javapackages-tools-3.4.1-11.el7.noarch

接下来安装oracle官方的jdk

[root@localhost home]# rpm -ivh jdk-8u181-linux-x64.rpm warning: jdk-8u181-linux-x64.rpm: Header V3 RSA/SHA256 Signature, key ID ec551f03: NOKEY Preparing... ################################# [100%] Updating / installing... 1:jdk1.8-2000:1.8.0_181-fcs ################################# [100%] Unpacking JAR files... tools.jar... plugin.jar... javaws.jar... deploy.jar... rt.jar... jsse.jar... charsets.jar... localedata.jar...

查看自己安装的jdk

[root@localhost home]#java -version java version "1.8.0_181" Java(TM) SE Runtime Environment (build 1.8.0_181-b13) Java HotSpot(TM) 64-Bit Server VM (build 25.181-b13, mixed mode)

参考：https://blog.51cto.com/11555417/2341784