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Asked: 2024-09-25T11:08:15+05:30 In:

How can I set up a persistent dummy network interface in Ubuntu 18.04? I’m looking for a step-by-step guide or any relevant methods to achieve this configuration.

I could really use some help with setting up a persistent dummy network interface in Ubuntu 18.04. I’ve been tinkering around with it, but I feel like I’m missing something important and it’s just not working the way I want it to. Let me give you some background.

So, I have this situation where I need a dummy network interface for some testing and development purposes. I want it to persist across reboots because I don’t want to keep setting it up every single time the system starts. I’ve looked through some tutorials and guides online, but they all seem a bit confusing or don’t cover the exact steps I need. Maybe I’ve missed something or maybe I’m just overcomplicating things.

I’m not a complete novice when it comes to Ubuntu or Linux in general, but sometimes these network configurations can get pretty tricky. I think I grasp the concept of dummy interfaces, but the nitty-gritty on how to make it persist is where I get lost. Is it something I can do by just editing some configuration files? If so, which files would I need to look at?

Also, I’ve seen some commands online that I think are meant to create a dummy interface, like using `ip link add dummy0 type dummy`, but I’m not sure how to make changes so that it survives a reboot. Do I need to use something like Netplan or another network management tool?

Honestly, if someone could lay out the steps in a straightforward way, without skipping over important bits, it would really help me out. Maybe share your experiences or any pitfalls to avoid if you’ve set one up before? Thanks in advance for any insights you can provide!

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    2 Answers

    1. To set up a persistent dummy network interface in Ubuntu 18.04, you need to create the dummy interface and configure it to survive reboots. Start by opening a terminal and create the dummy interface using the command `sudo ip link add dummy0 type dummy`. This creates the dummy interface, but it will disappear after a reboot. To make it persist, you’ll need to create a configuration file in the `/etc/network/interfaces.d/` directory. You can create a file called `dummy0` by running `sudo nano /etc/network/interfaces.d/dummy0` and add the following lines:

      auto dummy0
iface dummy0 inet static
    address 192.168.1.100
    netmask 255.255.255.0

      Replace `192.168.1.100` with the desired IP address for your dummy interface. The `netmask` can also be adjusted based on your requirements. Save the file and exit the text editor by pressing `CTRL+X`, then `Y`, followed by `Enter`. Finally, restart the networking service or reboot your machine to make sure the changes take effect. You can use `sudo systemctl restart networking` to apply the new configuration immediately. This method using `/etc/network/interfaces.d/` is straightforward and well-documented, so you’ll have your dummy network interface available across reboots without complications.



    2. Setting Up a Persistent Dummy Network Interface in Ubuntu 18.04

      Setting Up a Dummy Network Interface

      If you’re trying to set up a dummy network interface on Ubuntu 18.04 that persists across reboots, I totally get where you’re coming from! It’s a bit tricky, but here’s a simple way to do it.

      Steps to Create a Persistent Dummy Interface

      1. Load the dummy module:

        Before you create the dummy interface, make sure the dummy module is loaded. You can do this by running:

        sudo modprobe dummy
      2. Create the dummy interface:

        Use this command to create your dummy interface (usually named dummy0):

        sudo ip link add dummy0 type dummy
      3. Assign an IP address:

        Now, you’ll want to assign an IP address to it. For example:

        sudo ip addr add 192.168.1.100/24 dev dummy0
      4. Bring the interface up:

        Make sure the dummy interface is up with this command:

        sudo ip link set dummy0 up

      Make It Persistent Across Reboots

      So now that you’ve created the dummy interface, let’s make sure it sticks around after a reboot. Here’s how:

      1. Edit the Netplan configuration:

        Ubuntu 18.04 uses Netplan for network configuration. Open the Netplan configuration file (it’s usually in /etc/netplan/ and might be named something like 01-netcfg.yaml):

        sudo nano /etc/netplan/01-netcfg.yaml
      2. Add the dummy interface:

        In that file, you’ll want to add a block for your dummy interface. It should look something like this:

        
network:
    version: 2
    ethernets:
        dummy0:
            dhcp4: no
            addresses:
                - 192.168.1.100/24
      3. Apply the changes:

        Once you’ve added your interface, save the file and run:

        sudo netplan apply

      Reboot and Verify

      After doing all this, reboot your system:

      sudo reboot

      Once your system is back up, check if your dummy interface is still there by running:

      ip addr show dummy0

      Final Thoughts

      And that’s it! You should have a dummy interface that remains even after you restart your computer. If you run into any pitfalls, double-check your YAML formatting in the Netplan file—YAML is picky about spaces! Feel free to ask if you have any more questions or run into issues!


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