When configuring a Linux server as a router, troubleshooting a broken internet connection, or setting up complex virtualized environments, your very first step must be understanding the physical and virtual networking hardware attached to your machine. You cannot assign an IP address or bring a connection online if you do not know the exact system name of the network card. In modern Ubuntu Linux systems, the traditional ifconfig command has been replaced by the much more powerful and versatile iproute2 suite. To simply view and manage the state of your network interfaces, you use the ip link command.
The Basic ip link Command
The ip link command interacts specifically with the “link layer” (Layer 2) of the networking stack. This means it is concerned with the physical network cards (MAC addresses, interface names) and their raw operational state, rather than higher-level concepts like IP addresses.
To view all available network interfaces on your Ubuntu machine, open your terminal and type:
ip link show
Press Enter.
Interpreting the Output
The output will be a numbered list containing technical details for each detected interface.
- The Number and Name: Each entry starts with an index number followed by the interface name (e.g.,
1: lo:,2: enp3s0:,3: wlan0:).- lo: The loopback interface (used for internal communication).
- en… or eth…: Usually represents a physical wired Ethernet connection.
- wl… or wlan…: Usually represents a physical wireless Wi-Fi adapter.
- virbr… or docker…: Virtual bridge interfaces created by hypervisors or container systems.
- The State: Look at the text inside the angle brackets
< >. The most important flags here areUPorDOWN. This tells you if the network card is currently turned on and active. - The MAC Address: Look at the second line of each entry, starting with
link/ether. The hex string following it (e.g.,00:1a:2b:3c:4d:5e) is the permanent physical MAC address of that specific network card.
Using the Shortcut and Brief Modes
Like all ip commands, you can use abbreviations to save typing.
Instead of ip link show, you can simply type:
ip l
If you have dozens of virtual interfaces (such as when running Docker containers) and the output is too chaotic to read, use the -brief flag to compress the information into a highly readable table.
ip -brief link show
This outputs a single clean line per interface, showing only the name, its UP/DOWN status, and its MAC address.
How to View Only Active Interfaces
If your system has several disconnected network cards and you only want to see the ones that are currently turned on and functioning, you can filter the output using the up parameter.
ip link show up
This will strip away any interfaces that are currently powered down, allowing you to focus on the active connections.