Ethernet does not work with Ubuntu Server 20.04

Question

I want to install some packages via Ethernet, but it does not seem to be working. I want a DHCP connection.

Here is what I tried:

ifconfig (net-tools was installed via usb)

Which only gives LoopBack

Trying to modify the etc/network/interfaces file using cat etc/network/interfaces:

cat: /etc/network/interfaces: No such file or directory

I tried looking in the etc/network folder only to find that there are only 3 files:

if-post-down.d if-pre-up.d and if-up.d

Looking at /etc/netplan/00-installer-config.yaml it shows this:

  network:
        ethernets: {}
         version: 2

How can I solve this?

Solution

Netplan is the tool for configuring networks now.

• It's very easy to use, and here's whole page full of examples.

Step 1. Use ip addr to locate your interface name

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
2: enp3s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
3: wlp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state DOWN group default qlen 1000

• Here, you can see that my ethernet interface is named enp3s0.

Step 2. Modify the netplan YAML file. Here's an easy example:

• This requires a text editor and sudo, of course.

• Tip: Proper indentation is critical, Use spaces, NOT tabs.

  # This is a comment line - lines starting with # are ignored.
  network:
    version: 2
    renderer: networkd
    ethernets:
      enp3s0:           # Here is where that interface name goes!
        dhcp4: true
  

Step 3: Run sudo netplan apply. Netplan will parse and apply the new config, including requesting a new dhcp address.

After this, your network should be up.

• This config is for a server without GUI (networkd) using a wired ethernet (enp3s0) and dhcp. If you need a different configuration, check that page full of examples. What you want is probably in there.

Comments

[CodingM]

@user535733 I have looked in the /etc/netplan to find a file called 00-installer-config.yaml. Is this it? I have tried looking at it in vi.

[CodingM]

@user535733 I would like to try both, but for now I will try DHCP. I will edit the question to show the .yaml file.