Network Configuration Type

1. Static Temporary
2. DHCP Temporary
3. Static Permanently
4. DHCP Permanently

Static Temporary

ip address add [ipaddress/netmask-prefix] dev [iface-name]
ip address add 192.168.89.2/24 dev enp0s8
ip link set dev enp0s8 up

ip route add default via [gw-address] dev [iface-name]
ip route add default via 192.168.89.1 dev enp0s8
ip route add default via 192.168.89.1 dev enp0s8 metric 100 (if there is 2 interface with different gateway, https://askubuntu.com/questions/293827/error-rtnetlink-answers-file-exists).

DHCP Temporary

dhclient [iface-name]
dhclient enp0s8

Ubuntu 16.04
----------------
Static Permanently

vim /etc/network/interfaces

auto enp0s8
iface enp0s8 inet static
    address 192.168.88.2
    netmask 255.255.255.0
    gateway 192.168.88.1

service networking restart

DHCP Permanently

vim /etc/network/interfaces

auto enp0s8
iface enp0s8 inet dhcp

service networking restart

Ubuntu 18.04
----------------

Ubuntu 18.04 Bionic Beaver has switched to Netplan (/etc/netplan) for configuring network interfaces. This is a yaml based configuration system, which should simplify the process. To re-enable ifupdown on Ubuntu 18.04 system, you must install ifupdown package first.

Static Permanently

vim /etc/netplan/50-cloud-init.yaml

# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}

network:
    ethernets:
        enp0s8:
            addresses: [192.168.88.2/24]
            gateway4: 192.168.88.1
            nameservers:
              addresses: [8.8.8.8,8.8.4.4]
            dhcp4: no
    version: 2

Validate configuration : netplan try
Save configuration : netplan --debug apply

DHCP Permanently

vim /etc/netplan/50-cloud-init.yaml

# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}

network:
    ethernets:
        enp0s8:
            addresses:
            dhcp4: true
            optional: true
    version: 2

Validate configuration : netplan try
Save configuration : netplan --debug apply

Disable IPv6

echo "net.ipv6.conf.all.disable_ipv6 = 1" >> /etc/sysctl.conf; sysctl -p

DNS Resolver

Name resolution as it relates to IP networking is the process of mapping IP addresses to hostnames, making it easier to identify resources on a network. If you require DNS for your temporary network configuration, you can add DNS server IP addresses in the file /etc/resolv.conf. In general, editing /etc/resolv.conf directly is not recommanded, but this is a temporary and non-persistent configuration.

To configure the resolver permanently, add the IP addresses of the nameservers that are appropriate for your network to the netplan configuration file. You can also add an optional DNS suffix search-lists to match your network domain names.

nameservers:
search: [example.com, sales.example.com, dev.example.com]
addresses: [1.1.1.1, 8.8.8.8, 4.4.4.4]

Purge all IP Configuration

ip addr flush [iface-name]