How to perform a minimal installation of Ubuntu Server 18.04 LTS

How to perform a minimal installation of Ubuntu Server 18.04 LTS

Installation ISO

There are subtle but significant differences between a live-server installation and a traditional server installation. (See this and this)
After careful considerations, we decided to use the traditional one. Please make sure the name of the installation image contains server, amd64 but no live. The latest installation image can be found at Tsinghua Tuna. You should always choose the latest point release. At the time of writing, it is 18.04.2.

Pre-installation configurations

Follow the installer and use these configurations for each item.
If an item is empty, it means “make something up unless you have instructions from a network administrator”.

• Language: English
• Country: other => Asia => China
• Locale: United States - en_US.UTF-8
• Keyboard: English (US)
• Network: (this should be automatic when a DHCP server is available)

Manually configure network settings
NOTE: Please keep automatic configurations unless you have instructions from a network administrator.
When prompted for Hostname, select Go Back and choose Configure network manually.
Enter the designated IP address, netmask, gateway, nameserver when prompted.

• Hostname:
• Domain: xxxx.edu.cn
• User full name:
• Username:
• Password:
• Time zone: Asia/Chongqing (this should be automatic)
• Disk partition: Guided partitioning => Guided - use entire disk

Please let the installer partition the disk instead of doing it manually unless you understand how to partition disks and there are special requirements.

• Proxy server: (leave it blank)
• Configuring tasksel: No automatic updates
• Software selection: only OpenSSH server

Installation should begin now.

Post-installation configurations

Change APT mirror

Mirror list:

• mirrors.tuna.tsinghua.edu.cn (Tsinghua Tuna)
• mirrors.aliyun.com (Aliyun)
• ftp.sjtu.edu.cn (Shanghai Jiaotong University)

# Back up the old APT sources list
sudo cp /etc/apt/sources.list /etc/apt/sources.list.old
# Use an APT mirror
sudo sed -i 's/cn.archive.ubuntu.com/mirrors.tuna.tsinghua.edu.cn/g' /etc/apt/sources.list
sudo sed -i 's/security.ubuntu.com/mirrors.tuna.tsinghua.edu.cn/g' /etc/apt/sources.list
# Update from the new mirror
sudo apt update
sudo apt upgrade
# Clean up unnecessary dependencies
sudo apt autoremove

Disable iSCSI services

These two services may cause severe boot delay (about 5 minutes) under some circumstances. Better turn them off unless needed.

sudo systemctl disable iscsid.service open-iscsi.service

See this and this for details.

Configure Firewall

# Check UFW status
sudo ufw status verbose
# Deny all incoming connections by default
sudo ufw default deny incoming
# All all outgoing connections by default
sudo ufw default allow outgoing
# Allow SSH connections
sudo ufw allow ssh
# Allow HTTP and HTTPS
# Enable these two only if needed
sudo ufw allow http
sudo ufw allow https
# Check added rules
# Make sure ssh is allowed!!
sudo ufw show added
# Enable UFW
sudo ufw enable 
# Check UFW status
sudo ufw status verbose

See this link for additional information about UFW.