The bare-minimum that needs to be run when you first switch on a CentOS 7 VPS.

centos7_setup.sh

#!/bin/bash

# Update the system
yum update -y

# Add a non-root user
adduser jen
passwd jen
gpasswd -a jen wheel

# Edit the SSH daemon configuration to change the SSH port, disable root logins, and disable password logins
#
#     Port 57000
#     PermitRootLogin no
#     PasswordAuthentication no
vi /etc/ssh/sshd_config
systemctl reload sshd

# Get access to the `semanage` command to change the SSH port
yum install -y policycoreutils-python

# Make sure the firewall is installed and running
systemctl start firewalld
systemctl enable firewalld

# Change the port in `semanage` and in your firewall
semanage port -a -t ssh_port_t -p tcp 57000
firewall-cmd --permanent --remove-service=ssh
firewall-cmd --permanent --add-port=23000/tcp

# Go ahead and add some other services you'll need to the firewall
firewall-cmd --permanent --add-service=http
firewall-cmd --permanent --add-service=https

# Enable these firewall changes
firewall-cmd --reload

# Set the timezone and install the NTP service
timedatectl set-timezone America/New_York
yum install -y ntp
systemctl start ntpd
systemctl enable ntpd