Set a static IP on Ubuntu by writing a Netplan YAML file in /etc/netplan/, with dhcp4: no and an addresses: block, then running sudo netplan apply. The right file is 00-installer-config.yaml for a fresh install. The right verification is ip a show to see the new IP. The team that has the right YAML has a static IP that survives a reboot.
Table of contents
- The right YAML
- Finding the interface name
- Applying the config safely
- Common mistakes
- Verifying the change
- FAQ
The right YAML
The right Netplan YAML for a static IP:
network:
version: 2
renderer: networkd
ethernets:
enp0s3:
dhcp4: no
addresses:
- 192.168.1.100/24
routes:
- to: default
via: 192.168.1.1
nameservers:
addresses:
- 1.1.1.1
- 8.8.8.8Replace enp0s3 with the actual interface name. Replace 192.168.1.100/24 with the static IP and CIDR. Replace 192.168.1.1 with the gateway. Replace the nameservers with whatever you want to use.
Finding the interface name
The right command to find the interface name:
ip aThe output shows all interfaces with their names, IPs, and states. The right answer is to use the interface name that is state UP and has a link. The wrong answer is to use eth0 — modern systemd names interfaces based on the hardware (enp0s3, ens192, etc.).
Applying the config safely
The right command to apply the config:
sudo netplan applyThe right command for a remote box where the wrong config would lock you out:
sudo netplan trynetplan try reverts automatically after 120 seconds if the new config breaks connectivity. The right answer is to use try on remote boxes, apply on local boxes.
Common mistakes
The most common mistake is wrong indentation. Netplan YAML is whitespace-sensitive, and a single misplaced space causes netplan apply to fail. The right answer is two spaces per level, no tabs.
The second mistake is leaving dhcp4: yes while also specifying addresses:. The right answer is dhcp4: no for a static config.
The third mistake is a wrong CIDR. The right answer is to use the actual subnet’s CIDR. The wrong answer is to copy /24 from a tutorial and assume it works on every network.
Verifying the change
The right verification is three commands:
ip a show enp0s3
ip route
resolvectl statusip a shows the new IP. ip route shows the default route through the right gateway. resolvectl status shows the DNS servers.
FAQ
What if I lose connection after netplan apply?
Wait 120 seconds if you used netplan try — the old config comes back. If you used netplan apply and lost connection, the right answer is to use a cloud provider’s console or IPMI to access the box and revert the YAML.
Can I have multiple static IPs?
Yes. Add them to the addresses: list. The right answer is to ensure each is in the right subnet or with the right routing.
What about IPv6?
Replace dhcp4 with dhcp6 and add the IPv6 prefix to addresses:. The right answer is to set dhcp6: yes and use SLAAC for workstations; the right answer is to set dhcp6: no and specify the address for servers.
Why does my static IP not work after a reboot?
The most common cause is cloud-init overwriting the config. The right answer is to set network: {config: disabled} in /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg.
What is the difference between networkd and NetworkManager?
networkd is systemd’s network daemon, the right answer for servers. NetworkManager is the right answer for desktops. Netplan generates configs for whichever one is active.
Can I keep the file in a different name?
Yes, as long as it ends with .yaml. The files are applied in lexical order, so 00- files come before 99- files. The right answer is to use a higher number to override an earlier file.
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