Displaying Network Information with ip and nmcli

1. The Modern Way: The ip Command

For many years, the ifconfig command was the standard for viewing network information on Linux. However, it is now considered obsolete. Its modern, more powerful replacement is the ip command. We'll start here.

The most common way to use this command is to ask it to show your network addresses. To get a comprehensive look at your network interfaces and their assigned IP addresses, watch the first minute of this video.

As you saw, the command provides a lot of detail. Let's look at an example and break it down.

When you run ip a, you'll see a list of your network interfaces. Here’s what to look for:

• Interface Name: The entry starts with a number and the interface name (e.g., 1: lo, 2: enp0s3).
  • lo: This is the loopback interface. It's a virtual interface that the computer uses to communicate with itself. Its IP address is almost always 127.0.0.1.
  • enp... or eth...: These are typically wired Ethernet interfaces. The naming scheme can look complex, but it's designed to be predictable based on the hardware's physical location.
  • wlp...: These are Wireless LAN (Wi-Fi) interfaces.
• State: You'll see words like <UP,LOWER_UP> in the description. The most important part is UP, which means the interface is enabled and active.
• inet: This is the IPv4 address assigned to the interface. This is the "local" IP address you'll often need for development and testing. It's usually followed by a slash and a number (e.g., /24), which represents the subnet mask.
• inet6: This is the IPv6 address.

Do-It-Yourself: Find Your IP Address

Now it's your turn. Open your terminal and find your own IP address.

1. Run the command. You can use the shortest alias:

   ip a
   

2. Examine the output. Can you identify your main network interface? If you're connected via an Ethernet cable, it will likely be named enp.... If you're on Wi-Fi, it will be wlp....
3. Find the inet line for that interface. What is your system's IPv4 address on your local network?

This command gives you a direct, low-level look at the current state of your network hardware.

2. The Fedora Way: NetworkManager and nmcli

While the ip command is great for viewing the current state, modern Linux distributions like Fedora use a service called NetworkManager to actively manage network settings. It handles everything from switching between Wi-Fi networks to configuring VPNs.

To interact with NetworkManager from the command line, we use nmcli (NetworkManager Command-Line Interface). This is the tool you will use most often on Fedora for both viewing and changing network configurations.

To understand the role of NetworkManager and nmcli, please read the following article. It gives an excellent high-level overview.

Devices vs. Connections

A key concept in NetworkManager is the distinction between a device and a connection:

• A device is the physical hardware (e.g., your Ethernet port, your Wi-Fi card). You can see these with nmcli device.
• A connection is a software profile of settings (e.g., the Wi-Fi name and password, or the static IP configuration for your office). You can see these with nmcli connection.

A device is useless without a connection profile to tell it how to operate.

This next video provides a great demonstration of using nmcli to see both devices and connections.

Do-It-Yourself: Explore with nmcli

Let's use nmcli to explore your system's network configuration.

1. List Network Devices:
   See the physical hardware that NetworkManager recognizes.

   nmcli device status
   

   You can also use the short version: nmcli d. This lists your hardware, its type, its state (connected, disconnected, unavailable), and the connection profile it's currently using.

2. List Connection Profiles:
   Now, see the software profiles saved on your system.

   nmcli connection show
   

   Or the short version: nmcli c. This shows all the networks you've ever connected to, including your current one. The active connection will have its name listed under the DEVICE column. You can also see only the active connections with nmcli connection show --active.

3. Inspect Your Active Connection:
   This is where nmcli becomes very powerful. You can see every single detail about a specific connection profile. Find the name of your active connection from the previous step and use it in the command below. (If your connection name has spaces, enclose it in quotes, e.g., "My Home WiFi").

   nmcli connection show <your-connection-name>
   

   This output is very long! It contains all the configuration details. You can scroll through it, but it's often more useful to search it. Since you're learning Python and working in the terminal, you'll appreciate using pipes and grep to find exactly what you need.

   Try these commands, replacing <your-connection-name> as before:

   • Find your IP address and gateway:

     nmcli connection show <your-connection-name> | grep 'IP4.ADDRESS\|IP4.GATEWAY'
     

   • Find your DNS servers:

     nmcli connection show <your-connection-name> | grep 'IP4.DNS'
     

   • Check if you are getting your IP automatically (via DHCP) or if it's set manually:

     nmcli connection show <your-connection-name> | grep 'ipv4.method'
     

     auto means DHCP, manual means it's a static IP.

Summary and What's Next

Great work! You now have two powerful tools to inspect your network configuration. Let's quickly recap their roles:

Key Takeaways:

• ip a gives you a quick, low-level view of all network interfaces and the IP addresses currently assigned to them. It's great for a fast status check.
• nmcli is the command-line interface for NetworkManager, the service that manages your network configurations on Fedora.
  • nmcli device shows the state of your physical network hardware.
  • nmcli connection shows the software profiles and lets you inspect their detailed settings, like IP addresses, gateways, and DNS servers.

You've learned how to view the configuration. In our next lesson, we'll take the logical next step: you will learn how to modify a network connection using nmcli, such as setting a static IP address for your development server.