Ubuntu Server Networking


Network Configuration

Identify the Ethernet Interfaces:
$ ip link
The Ethernet Interfaces are located in /sys/class/net

For detail hardware information, use lshw:
$ sudo lshw -class network

Other program is ethtool, it’s not installed in Ubuntu by default.
$ sudo apt install ethtool

Static IP Address Assignment

To configure static IP address assignment, add the static method to the inet address family statement for the appropriate interface in the file /etc/network/interfaces.
$ sudo vi /etc/network/interfaces

In this example, the name of the interface is enp0s3 instead of eth0:

auto enp0s3
iface enp0s3 inet static
# Optional MTU size, Jumbo Frame
mtu 9216

By adding an interface to the configuration file, enable the interface:
$ sudo ifup enp0s3

To manually disable the interface, you can use the ifdown command:
$ sudo ifdown enp0s3

To Re-start Networking service:
$ sudo /etc/init.d/networking restart

DHCP IP Address

To use DHCP, add the dhcp in the inet line instead of static:

$ sudo /etc/network/interfaces
auto enp0s3
iface enp0s3 inet dhcp
Temporary IP Address Assignment

Use ifconfig:

$ sudo ifconfig enp0s3 netmask
$ sudo route add default gw enp0s3

To remove the Temporary IP Address:
$ sudo ip addr flush enp0s3