centos7

centos7 Initialization script (Google Cloud VM instance)
for system administrators

Steps

• Disable firewalld, download and enable iptables

sudo systemctl stop firewalld.service
sudo systemctl disable firewalld.service 
sudo yum -y install iptables-services
sudo sed -i '/--dport 22/a-A INPUT -p tcp -m state --state NEW -m tcp --dport 6666 -j ACCEPT' /etc/sysconfig/iptables
sudo systemctl start iptables.service
sudo systemctl enable iptables.service

• Puttygen generate ssh key, and add public key to GCP Compute Engine Metadata, in order to ssh from putty
• Disable selinux

sudo sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config

• Change ssh port from 22 to port 6666

sudo sed -i 's/^#Port 22/Port 6666/g' /etc/ssh/sshd_config

• Download some common tools

sudo yum -y install wget
sudo yum -y install vim
sudo yum -y install telnet telnet-server xinetd
sudo systemctl enable telnet.socket
sudo systemctl start telnet.socket
sudo systemctl enable xinetd
sudo systemctl start xinetd
sudo yum -y install net-tools
sudo yum -y install traceroute
sudo yum -y install lsof
sudo yum -y install sysstat
sudo yum -y install nc 
sudo yum -y install tcpdump
sudo yum -y install tree
sudo yum -y install bind-utils
sudo yum -y install nmap
sudo yum -y install git
sudo yum -y install unzip
sudo yum -y install zip
sudo yum -y install sshpass
sudo yum -y install pciutils

• Install Docker and Docker-compose

#Docker
sudo yum install -y yum-utils device-mapper-persistent-data lvm2
sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
sudo yum -y install docker-ce
sudo systemctl enable docker.service
sudo systemctl start docker.service
#Docker-compose
sudo yum -y install epel-release
sudo yum -y install python-pip
sudo pip install docker-compose
sudo yum upgrade python*

• Install ntpdate and add to cron job

yum -y install ntpdate
(crontab -l 2>/dev/null; echo "*/5 * * * * ntpdate 1.sg.pool.ntp.org") | crontab -
# The 2>/dev/null is important so that you don't get the no crontab for username message that some *nixes produce if there are currently no crontab entries.

• Install Nodejs and Yarn

#Check version of Node first on official website, current stable version is 10.x. Change below number accordingly in future
curl -sL https://rpm.nodesource.com/setup_10.x | sudo bash -
sudo yum -y install nodejs
curl --silent --location https://dl.yarnpkg.com/rpm/yarn.repo | sudo tee /etc/yum.repos.d/yarn.repo
sudo yum -y install yarn

• Add user and set password

useradd -s /bin/bash fuhx
# In centos 7 the useradd command will automatically create the home folder, but in ubuntu 18.04 it will not
echo "fuhx    ALL=(ALL)       ALL" >> /etc/sudoers
echo fuhx:your_password | chpasswd
# modify "your_password" to the real password

• Install Google authenticator and configure for user fuhx

sudo yum -y install google-authenticator
# Turn on overall switch
echo "auth required pam_google_authenticator.so" >> /etc/pam.d/sshd
sed -i 's/ChallengeResponseAuthentication no/ChallengeResponseAuthentication yes/g' /etc/ssh/sshd_config
sudo systemctl restart sshd
su fuhx
# Configure google authenticator for fuhx
google-authenticator << EOF
y
y
y
n
y
EOF
exit

• Restart server

sudo shutdown -r now