Systemd-networkd-wait-online Waiting For Ethernet That Is Not There

Introduction

When setting up a Linux system, especially one that will be used in a variety of environments, it's essential to consider the network configuration. In this article, we'll discuss a common issue that can arise when using systemd-networkd-wait-online on Ubuntu 24.04.2, specifically when waiting for an Ethernet connection that is not present.

Understanding Systemd-networkd-wait-online

Systemd-networkd-wait-online is a service that waits for network interfaces to come online before proceeding with the boot process. This is particularly useful in environments where network connectivity is critical, such as in cloud or virtualized environments. However, when dealing with systems that have multiple network interfaces, including Ethernet and Wi-Fi, systemd-networkd-wait-online can sometimes get stuck waiting for an interface that is not present.

The Problem: Waiting for Ethernet that is Not There

In our scenario, we have an instance of Ubuntu 24.04.2 with both an onboard Ethernet card and a PCIe Wi-Fi card. Both cards work and connect as needed. However, when we use systemd-networkd-wait-online to wait for the network to come online, it gets stuck waiting for the Ethernet interface, which is not present.

Symptoms and Diagnosis

When systemd-networkd-wait-online is waiting for the Ethernet interface, you may experience the following symptoms:

• The system will hang or freeze during the boot process.
• The systemd-networkd-wait-online service will be stuck in a loop, continuously checking the Ethernet interface.
• You may see error messages indicating that the Ethernet interface is not present or is not responding.

To diagnose the issue, you can check the systemd-networkd-wait-online service logs for errors. You can also use the systemctl status command to check the status of the service and see if it's stuck waiting for the Ethernet interface.

Solutions and Workarounds

To resolve the issue, you can try the following solutions and workarounds:

1. Disable Ethernet Interface

One possible solution is to disable the Ethernet interface altogether. You can do this by editing the /etc/network/interfaces file and commenting out the Ethernet interface configuration.

sudo nano /etc/network/interfaces

Comment out the Ethernet interface configuration by adding a # symbol at the beginning of each line.

# auto eth0
# iface eth0 inet dhcp

Save and close the file. Then, restart the systemd-networkd service to apply the changes.

sudo systemctl restart systemd-networkd

2. Use a Different Network Manager

Another solution is to use a different network manager, such as NetworkManager. NetworkManager is a more traditional network manager that can handle multiple network interfaces and can be configured to ignore the Ethernet interface.

To install NetworkManager, run the following command:

sudo apt-get install network-manager

Then, restart the system to apply the changes.

3. Configure Systemd-networkd-wait-online

You can also configure systemd-networkd-wait-online to ignore the Ethernet interface. To do this, edit the /etc/systemd/network/-default.link file and add the following line:

[Link]
NamePolicy=kernel database onboard
IgnoreCarrier=yes

This will tell systemd-networkd-wait-online to ignore the Ethernet interface and wait for the Wi-Fi interface instead.

Save and close the file. Then, restart the systemd-networkd service to apply the changes.

sudo systemctl restart systemd-networkd

Conclusion

In conclusion, systemd-networkd-wait-online can sometimes get stuck waiting for an Ethernet interface that is not present. To resolve this issue, you can try disabling the Ethernet interface, using a different network manager, or configuring systemd-networkd-wait-online to ignore the Ethernet interface. By following these solutions and workarounds, you can ensure that your system boots up quickly and efficiently, even in environments where network connectivity is critical.

Additional Resources

For more information on systemd-networkd-wait-online and network configuration on Ubuntu, you can refer to the following resources:

• Systemd-networkd-wait-online man page
• Ubuntu documentation on network configuration
• Systemd-networkd documentation

Troubleshooting Tips

If you're still experiencing issues with systemd-networkd-wait-online, here are some additional troubleshooting tips:

• Check the systemd-networkd-wait-online service logs for errors.
• Use the systemctl status command to check the status of the service.
• Try disabling the Ethernet interface and see if the issue persists.
• Try using a different network manager, such as NetworkManager.
• Check the network configuration files, such as /etc/network/interfaces and /etc/systemd/network/99-default.link, for any errors or inconsistencies.
  Systemd-networkd-wait-online Q&A =====================================

Frequently Asked Questions and Answers

Q: What is systemd-networkd-wait-online?

A: Systemd-networkd-wait-online is a service that waits for network interfaces to come online before proceeding with the boot process.

Q: Why is systemd-networkd-wait-online getting stuck?

A: Systemd-networkd-wait-online can get stuck waiting for an Ethernet interface that is not present. This can happen when the system has multiple network interfaces, including Ethernet and Wi-Fi.

Q: How can I disable the Ethernet interface?

A: To disable the Ethernet interface, you can edit the /etc/network/interfaces file and comment out the Ethernet interface configuration. Then, restart the systemd-networkd service to apply the changes.

Q: Can I use a different network manager?

A: Yes, you can use a different network manager, such as NetworkManager. NetworkManager is a more traditional network manager that can handle multiple network interfaces and can be configured to ignore the Ethernet interface.

Q: How can I configure systemd-networkd-wait-online to ignore the Ethernet interface?

A: To configure systemd-networkd-wait-online to ignore the Ethernet interface, you can edit the /etc/systemd/network/-default.link file and add the following line:

[Link]
NamePolicy=kernel database onboard
IgnoreCarrier=yes

Then, restart the systemd-networkd service to apply the changes.

Q: What are some common issues with systemd-networkd-wait-online?

A: Some common issues with systemd-networkd-wait-online include:

• Getting stuck waiting for an Ethernet interface that is not present
• Not waiting for the correct network interface
• Not handling multiple network interfaces correctly

Q: How can I troubleshoot systemd-networkd-wait-online issues?

A: To troubleshoot systemd-networkd-wait-online issues, you can:

• Check the systemd-networkd-wait-online service logs for errors
• Use the systemctl status command to check the status of the service
• Try disabling the Ethernet interface and see if the issue persists
• Try using a different network manager, such as NetworkManager
• Check the network configuration files, such as /etc/network/interfaces and /etc/systemd/network/99-default.link, for any errors or inconsistencies

Q: Can I configure systemd-networkd-wait-online to wait for a specific network interface?

A: Yes, you can configure systemd-networkd-wait-online to wait for a specific network interface. To do this, you can edit the /etc/systemd/network/-default.link file and add the following line:

[Link]
Name=eth0

Then, restart the systemd-networkd service to apply the changes.

Q: How can I configure systemd-networkd-wait-online to ignore a specific network interface?

A: To configure systemd-networkd-wait-online to ignore a specific network interface, you can edit the /etc/systemd/network/-default.link file and add the following line:

[]
Name=eth0
IgnoreCarrier=yes

Then, restart the systemd-networkd service to apply the changes.

Q: Can I use systemd-networkd-wait-online with multiple network interfaces?

A: Yes, you can use systemd-networkd-wait-online with multiple network interfaces. However, you may need to configure systemd-networkd-wait-online to wait for the correct network interface.

Q: How can I configure systemd-networkd-wait-online to wait for multiple network interfaces?

A: To configure systemd-networkd-wait-online to wait for multiple network interfaces, you can edit the /etc/systemd/network/-default.link file and add the following lines:

[Link]
Name=eth0
WaitForNetwork=yes
[Link]
Name=wlan0
WaitForNetwork=yes

Then, restart the systemd-networkd service to apply the changes.

Q: Can I use systemd-networkd-wait-online with NetworkManager?

A: Yes, you can use systemd-networkd-wait-online with NetworkManager. However, you may need to configure NetworkManager to ignore the Ethernet interface.

Q: How can I configure NetworkManager to ignore the Ethernet interface?

A: To configure NetworkManager to ignore the Ethernet interface, you can edit the /etc/NetworkManager/system-connections/ file and add the following line:

[connection]
ignore-carrier=yes

Then, restart the NetworkManager service to apply the changes.

Conclusion

In conclusion, systemd-networkd-wait-online can be a powerful tool for managing network interfaces on Linux systems. However, it can also be prone to issues, such as getting stuck waiting for an Ethernet interface that is not present. By following the solutions and workarounds outlined in this article, you can troubleshoot and resolve common issues with systemd-networkd-wait-online.