USB Redirection in KVM: Native method vs. USB Network Gate

USB redirection in Linux is necessary to use KVMs (Kernel-based virtual machines) for anything other than the most basic tasks. By default, only a keyboard and mouse are enabled in QEMU virtual machines, but you can redirect other devices, such as microphones, webcams, and storage devices into a VM with the help of QEMU/KVM native tools or a third-party solution, such as USB Network Gate.

1. Why do you need USB redirection?
2. Native Linux solution - KVM USB Redirection options.
3. KVM USB Redirection with USB Network Gate
4. Comparison table
5. Conclusion

Why USB Redirection in KVM?

USB redirection enables:

• Access to physical USB devices like printers, webcams, and storage devices inside VMs.
• The use of specialized USB hardware like security keys or diagnostic tools.
• Redirection of USB devices over a network (with USB Network Gate).

Solution 1: Native Linux USB Redirection Using QEMU/KVM

QEMU, the emulator and virtualizer behind KVM, provides a built-in mechanism for USB redirection. You can either have the device connected on startup or use monitor commands to connect or disconnect USB devices while the machine is running.

Note: xawtv is a simple way to check whether your webcam is working, and xev or antimicro will help you test controllers such as keyboards and mice. Both are available on most popular Linux distributions.

Note: if you’re planning to use device_del, make sure to add an id=[name of your choice] argument to the device_add command, so you can refer to the device you want to eject.

Advantages of the Native Linux Solution

✔ Free and Open-Source: Fully integrated into QEMU/KVM.

✔ Customizable: Allows fine-tuned configuration for specific devices.

✔ Lightweight: No need for additional software.

Limitations

✖ Local Access Only: USB redirection is limited to devices physically connected to the host.

✖ Complexity: Command-line and XML configurations can be challenging for beginners.

Solution 2: USB Network Gate

Advantages of USB Network Gate

✔ Network Access: Easily share USB devices over LAN, WAN, or the internet.

✔ Cross-Platform Support: Works with Linux, Windows, and macOS.

✔ User-Friendly: Simple interface with minimal setup required.

Limitations

✖ Cost: USB Network Gate requires a paid license.

✖ Dependency on Software: Both the host and guest must have the software installed.

Which Solution is Right for You?

Choose the native Linux solution if:

• You only need to redirect USB devices locally.
• You prefer a cost-free, open-source approach.
• You are comfortable with CLI or XML-based configuration.
  
  

Choose USB Network Gate if:

• You need to redirect USB devices over a network or share them between multiple VMs.
• You require cross-platform compatibility.
• You prefer a user-friendly solution with minimal setup.

Conclusion

USB redirection in KVM is a powerful feature that can be achieved using either QEMU/KVM native tools or USB Network Gate. The native Linux solution is ideal for local, cost-free setups, while USB Network Gate provides advanced functionality for remote and networked environments. Depending on your use case, either solution can provide reliable USB access in virtualized environments.