Setting IP Address on Linux

July 20, 2024

Table of Contents

• Problem
• Solution
• Sources

---

Problem

I have a 22.04LTS Ubuntu machine and I want to change the IP address on it. There are several methods to check the current IP address:

1. ip a (shorthand, ip addr, ip address or ip addr show. shows info for all interfaces)
2. ifconfig (needed installation)
3. hostname -I (concise output)
4. nmcli device show (similar to #1)

Solution

the routine to change the IP address includes disabling the interface, changing IP and enabling it again:

1. ip link set <interface> down
2. ip addr add <ip>/<subnet> dev <interface>
3. ip link set <interface> up

however I came across a method using netplan, by modifying a .yaml config file. this is how it goes:

1. locate config netplan files: ls /etc/netplan
2. the contents in that folder depends on the machine:
3. user-defined configs are typically named 01-netcfg.yaml
4. config created by NetworkManager is often named 01-network-manager-all.yaml
5. 00-installer-config.yaml is a common name for configs that are generated while installing, often on a server, and can contain network defaults
6. filenames are important, since netplan processes files alphabetically (so 00-* files are processed before 01-* files, etc.)
7. the renderer also matters, and determines how the settings are applied (e.g., using NetworkManager or networkd)
8. backup the original config (in case you mess something up like I did)
9. edit the proper .yaml file
10. netplan apply
11. ping to verify

this was my initial config :

# Let NetworkManager manage all devices on this system
network:
  version: 2
  renderer: NetworkManager

an example config looks like below:

network:
  version: 2
  renderer: networkd  # or NetworkManager
  ethernets:
    enp0s3:  # Replace with your interface name
      dhcp4: no
      addresses:
        - 192.168.1.100/24  # Replace with your desired static IP
      gateway4: 192.168.1.1  # Replace with your gateway IP
      nameservers:
        addresses:
          - 8.8.8.8          # Primary DNS
          - 8.8.4.4          # Secondary DNS

⚠️ YAML files
human-readable markup language
highly sensitive to whitespaces, indentations, case/caps, etc.
take extra care

Sources

1. https://pimylifeup.com/ubuntu-static-ip-netplan/
2. https://ostechnix.com/configure-static-ip-address-ubuntu/
3. https://www.serverlab.ca/tutorials/linux/administration-linux/how-to-configure-networking-in-ubuntu-20-04-with-netplan/