1.关闭防火墙

systemctl stop firewalld
systemctl disable firewalld

hadoop01:

hadoop02:

2.关闭 SELinux（防止进程读写目录被 deny）

sed -i 's/^SELINUX=.*/SELINUX=disabled/' /etc/selinux/config
setenforce 0          

同样套路改 hadoop02

3.时间同步

① 安装并启用 NTP

CentOS 7 官方源已停止维护 换阿里源

ping 8.8.8.8 -c 3  #先让yum能联网

curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
sed -i 's/$releasever/7/g' /etc/yum.repos.d/CentOS-Base.repo
yum clean all && yum makecache

yum -y install ntp
systemctl enable ntpd
systemctl start ntpd

② 立刻同步一次

ntpdate -u pool.ntp.org

③ 设为开机自启（11min)

echo "*/11 * * * * /usr/sbin/ntpdate -u pool.ntp.org > /dev/null 2>&1" >> /var/spool/cron/root

date                            #验证
timedatectl status | grep NTP   #应显示 active (yes)