The first thing after starting centos7 cloud server

1. Modify the hostname
1.1. View the hostname

[root@ball-1 data]# hostnamectl status
   Static hostname: ball-1
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 45461f76679f48ee96e95da6cc798cc8
           Boot ID: a2f12ecd869045d695586365479419d9
    Virtualization: xen
  Operating System: CentOS Linux 7 (Core)
       CPE OS Name: cpe:/o:centos:centos:7
            Kernel: Linux 3.10.0-123.9.3.el7.x86_64
      Architecture: x86_64
[root@ball-1 data]#

1.2. Modification

sudo hostnamectl set-hostname "my-host-name"

2. Enlarge the ssh port
2.1, modify the port

vi /etc/ssh/sshd_config
Port 24367

2.2, restart the ssh service

systemctl restart sshd.service

3. Turn off selinux
3.1, check the status of selinux

sestatus
[root@ball-1 data]# sestatus
SELinux status:                 disabled

3.2. If enable means enable, then close

vi /etc/selinux/config
Modify SELINUX=disabled

4. Enable iptables,
#Not used to firewall #Still
used to iptables

4.1, close firewall

systemctl stop firewalld.service
systemctl disable firewalld.service

4.2, enable iptables

yum install iptables-services
vi /etc/sysconfig/iptables
content:
# Firewall configuration written by system-config-securitylevel
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:MY-Firewall-1-INPUT - [0:0]
-A INPUT -j MY-Firewall-1-INPUT
-A FORWARD -j MY-Firewall-1-INPUT
-A MY-Firewall-1-INPUT -i lo -j ACCEPT
-A MY-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT
-A MY-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A MY-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A MY-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A MY-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT
-A MY-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT

#start iptables
systemctl restart iptables.service
#Configure startup
systemctl enable iptables.service