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Can I use my USB License Key Dongle Passthrough in a VM?

To use your Wowza Streaming Engine USB License Key with a virtual machine, you would need to configure USB passthrough correctly on the VM instance; otherwise you may run into the error "ST key not found".

Problem: You have installed Wowza Streaming Engine on your Hyper-V VM and it starts up correctly with a standard, test or trial license key. You need to use your USB license key as a no-check-in licensing scheme. You've created the lib-license folder in the Wowza installation directory, copied the required wms-license-usb-st.jar file to this folder, and edited the conf/Server.license with the encrypted license key text. But when you start up your Wowza Streaming Engine services, you are getting the following errors in your access log files.

WARN    200     -       USB Key licensing system: ST key not found.
ERROR   500     -       The Wowza Media Systems Software licensing system has determined that your license key is not able to authenticate against the usb key hardware licensing system, please visit http://www.wowza.com/subscriptionsupport.php for up to date information.

This article explains troubleshooting steps and configuration options, based on documented resolutions, to address USB dongle passthrough problems in a virtualized machine environment, such as Hyper-V, Proxmox VE, or VMWare.

Why this can happen
  • The Wowza Streaming Engine USB license key is a security key and not a typical USB hard drive. It requires USB passthrough to be supported by the OS platform.
  • A USB dongle that works on the physical host and in other hypervisors (for example, VMware) may still not be accessible from a Hyper-V guest because Hyper-V handles USB passthrough differently.
  • A VM that can see basic USB devices (for example, mass‑storage USB sticks) may still fail to see certain specialized USB dongles.
Troubleshooting and configuration checklist
  1. Ensure validity of your lib-license folder
    • This folder should be in your Wowza Streaming Engine installation directory.
    • Make sure you have the wms-license-usb-st.jar file in this folder. If you see a generated .dll or .so file in this folder, check that these files are not 0 bytes in size. If the files exist and have an invalid size, delete them and restart the Wowza services.
  2. Verify host USB operation
    • Confirm the USB dongle operates correctly on the physical host before testing the VM.
    • Check the host OS can use the dongle normally.
  3. Check Device Manager on the host
    • Open Device Manager on the host to verify the dongle appears and is recognized by the host operating system.
    • If the dongle does not appear in Device Manager, focus on resolving host recognition first.
  4. Confirm VM guest USB behavior with other devices
    • Test simpler USB devices (for example, USB memory sticks) in the VM guest to verify the VM’s basic USB handling is functional.
    • If the guest recognizes other USB devices but not the dongle, the issue is likely specific to passthrough of that dongle type.
  5. Review your VM's passthrough settings
    • Verify your virtualization software's USB passthrough settings and any configuration requirements.
    • Check with the current documentation for your virtualization software on what is supported.
  6. Consider virtualization differences
    • If the dongle works on other hypervisors (for example, VMware) but not Hyper-V, treat the behavior as a Hyper-V-specific passthrough or configuration limitation and review Hyper-V documentation and platform settings accordingly.
    • Coordinate with the system administrator or virtualization platform support team to validate Hyper-V-specific configuration options for USB device access.
  7. Use USB-over-network tools when passthrough is limited
    • If the virtualization software cannot passthrough the dongle natively, use of a USB-over-network solution may be possible to present the dongle to the guest. Note that this is NOT a recommended solution and may not consistently work.
    • An example solution that some users have reported to have resolved this issue is VirtualHere (USB over IP). Deploying VirtualHere allowed the Hyper-V guest to access the USB dongle successfully.
Practical sequence to resolve a non‑working dongle in Hyper-V and other VM software
  1. Confirm the dongle functions on the physical host.
  2. Check Device Manager on the host to confirm the device is present.
  3. Test other USB devices in the VM guest to confirm guest USB handling.
  4. Review and enable passthrough-related settings (including Enhanced Session Mode if available).
  5. If your virtualization software configuration does not allow the dongle to be passed through, try deploying a USB-over-network tool (for example, VirtualHere) to expose the device to the VM.

Conclusion: When a USB dongle is recognized on the host and other hypervisors but not in a Hyper-V VM, focus on Hyper-V passthrough configuration and session/USB redirection settings. If native passthrough is limited, a USB-over-network solution such as VirtualHere may (but not guaranteed to) provide a working alternative to make the dongle available inside the VM. If this still fails, then you would need to use a bare-metal solution instead or a different virtualization software.