Installing CentOS 7

Please note: This instruction was created for my personal use. Feel free to follow it, but I am not responsible for any problems or data loss!

Download the network install CD, which can be found at: http://ftp.tudelft.nl/centos.org/7/isos/x86_64/CentOS-7-x86_64-NetInstall-2009.iso. Check the MD5 sum by running md5sum on CentOS-7-x86_64-NetInstall-2009.iso and compare the result to the SHA256 sums at: http://ftp.tudelft.nl/centos.org/7/isos/x86_64/sha256sum.txt.

Boot from the network install CD. Make sure you have at least 768MB of memory available, or you will not be able to create a custom harddisk layout.

Select Install CentOS 7 at the CD boot screen. Set the installation language to English; Keyboard: English (United States). Set the Date&Time options. Click the Installation Source setting, select Network and enter the correct URL: http://ftp.tudelft.nl/centos.org/7/os/x86_64/

• Select the U.S. English keyboard layout.
• Select Basic Storate Devices (unless you are installing to a SAN).
• Enter the hostname you would like to use (do not add the domain name).
• Select the correct timezone and make sure System uses UTC is enabled.
• Enter the root password.
• Select Create Custom Layout and create a primary partition for the OS and one for swap (create a swap partition as large as the amount of memory you have).
• Use the ext4 filesystem for all partitions (instead of XFS)
• Use the provided boot loader configuration.
• Select the Minimal installation option.
• Wait for the installation to finish.
• Reboot the system.

• Add the EPEL repository by running: yum install epel-release
• Install the following packages:

yum install -y yum-utils sysstat iotop strace tcpdump lsof ntp ntpdate man man-pages mlocate wget perl iptraf-ng bind-utils net-tools psmisc vim-enhanced rsync lynx atop screen

• Add the noatime option to all ext3/ext4/XFS/etc filesystem options in /etc/fstab
• Edit /etc/default/grub and remove the rhgb and quiet options from GRUB_CMDLINE_LINUX. Replace these options with: nomodeset vga=normal consoleblank=0 (add elevator=none when running on an SSD or in a VM)
• Create a new grub2 config file using: grub2-mkconfig > /boot/grub2/grub.cfg
• Update the system: yum upgrade
• Add a normal user, to log in as: useradd -m username
• Set a password: passwd username
• Add the normal user to the wheel group: usermod -a -G wheel username
• Make sure root cannot log in via ssh by changing /etc/ssh/sshd_config:
  • PermitRootLogin prohibit-password
  • This will disable logging in as root, via ssh, but it is still possible to log in as root using SSH public key authentication.
• Disable SELinux by setting SELINUX=disabled in /etc/sysconfig/selinux (a reboot is needed to fully disable SELinux. Do not disable SELinux for production systems)
• Disable the firewall (when in a secure network), by running: systemctl disable firewalld
• Enable irqbalance: systemctl enable irqbalance.service (only useful on an SMP system)
• Set up /etc/ntp.conf:

driftfile /var/lib/ntp/drift
restrict default nomodify notrap nopeer noquery
restrict 127.0.0.1 
restrict ::1
server 0.nl.pool.ntp.org
server 1.nl.pool.ntp.org
server 2.nl.pool.ntp.org
server 3.nl.pool.ntp.org

• Change /etc/ntp/step-tickers:

0.nl.pool.ntp.org
1.nl.pool.ntp.org

• Enable ntpdate and ntpd: systemctl enable ntpdate ; systemctl enable ntpd
• Reboot the system to activate all changes

-- Ivo van Geel - 19 Nov 2014