RDP USB Passthrough for Windows 11 Pro

USB device redirection over RDP on Windows 11 Pro — two patches that make it work.

The Problem

Windows 11 Pro has full USB redirection infrastructure (drivers, services, protocol support) but artificially blocks it through a licensing check. When you try to redirect a USB device via RDP, the server logs:

Event ID 36: "Redirection of additional supported devices is disabled by policy."

This happens because umrdp.dll calls SLGetWindowsInformationDWORD("TerminalServices-RemoteConnectionManager-AllowAppServerMode") which returns 0 on non-Server editions. No amount of registry or Group Policy changes can fix this — the check is hardcoded in the binary.

Additionally, FreeRDP 3.x has a bug where USB devices connected through hub chains get incorrect device paths, causing the wrong device to be redirected.

What's Here

1. FreeRDP URBDRC Device Path Fix

freerdp-urbdrc-devpath.patch — Fixes device path generation in FreeRDP's URBDRC (USB Redirection) channel.

Bug: libusb_get_port_numbers() returns the full USB topology (e.g., [5,2,1,1,3]) but FreeRDP only uses the last port number, generating path 1-3 instead of 1-5.2.1.1.3. This causes redirection of the wrong device.

cd /path/to/freerdp-source
git apply /path/to/freerdp-urbdrc-devpath.patch
# rebuild and install

2. Windows umrdp.dll Licensing Bypass

patch-umrdp.py — Patches umrdp.dll to bypass the AllowAppServerMode licensing check.

The patch NOPs out a single conditional jump (6 bytes at offset 0x9001), allowing the USB redirection code path to execute regardless of the licensing result.

Offset 0x9001:  0F 84 BA 00 00 00  (je +0xBA)
             -> 90 90 90 90 90 90  (6x NOP)

Targets umrdp.dll version 10.0.26100.1 (Windows 11 24H2). The script includes a signature check and will refuse to patch an unrecognized version.

3. Server Setup Script

setup-server.ps1 — One-shot PowerShell script that configures everything on the Windows side:

• Registry values (fDisableUSBRedir, EnableUSBRedirection, fUsbRedirectionEnableMode)
• USB class filter registration (TsUsbFlt as UpperFilter)
• Service configuration (TsUsbFlt, TsUsbGD, tsusbhub, UmRdpService)
• Binary patch of umrdp.dll

Run as Administrator, then reboot.

Quick Start

Windows Side (the RDP server)

# Run as Administrator
Set-ExecutionPolicy Bypass -Scope Process
.\setup-server.ps1
Restart-Computer

Linux Side (the RDP client)

# Apply the FreeRDP patch and rebuild
cd /path/to/freerdp-source
git apply freerdp-urbdrc-devpath.patch
mkdir build && cd build
cmake .. && make -j$(nproc)
sudo make install

# Connect with USB redirection (example: Logitech SpaceMouse 046d:c62b)
xfreerdp3 /v:SERVER /u:USER /p:PASS /usb:id:046d:c62b /cert:ignore

How It Works

RDP USB Redirection Architecture

Linux Client                          Windows Server
─────────────                         ──────────────
xfreerdp3                             termsrv.dll (RDP core)
  └─ URBDRC channel ──── DVC ────────── rdpcorets.dll
       └─ libusb                          └─ umrdp.dll (policy check) ← PATCHED
            └─ device enum                     └─ tsusbhub.sys (USB hub driver)
                                                    └─ TsUsbFlt.sys (class filter)
                                                         └─ USB device appears in Windows

The Licensing Check (what we bypass)

// umrdp.dll pseudocode at 0x8FF7
BOOL enabled = CheckUsbRedirectionLicense();  // calls SLGetWindowsInformationDWORD
if (!enabled) {                                // AllowAppServerMode == 0 on Win11 Pro
    LogEvent(36, "disabled by policy");        // ← this is the error everyone sees
    return;
}
// ... proceed with USB redirection

The Device Path Bug (what we fix)

USB topology: Bus 1, Port chain [5, 2, 1, 1, 3]

FreeRDP (before): path = "1-3"     (wrong — matches a different device!)
FreeRDP (after):  path = "1-5.2.1.1.3"  (correct full topology)

Registry Values Reference

Path	Value	Type	Data	Purpose
HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services	fDisableUSBRedir	DWORD	0	Don't disable USB redir
HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services	EnableUSBRedirection	DWORD	1	Enable USB redir
HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services	fUsbRedirectionEnableMode	DWORD	2	Allow admins and users
HKLM\SOFTWARE\Policies\...\Client	fUsbRedirectionEnableMode	DWORD	2	Client-side enable
HKLM\SYSTEM\...\Control\Class\{36fc9e60-...}	UpperFilters	MULTI_SZ	TsUsbFlt	USB hub class filter

Tested With

• Server: Windows 11 Pro 24H2 (Nano11), build 26100.1
• Client: Arch Linux, FreeRDP 3.23.0
• Device: Logitech/3Dconnexion SpaceMouse Pro (046d:c62b)

Disclaimer

This project modifies system binaries and bypasses licensing checks. Use at your own risk and only on machines you own. Windows Update may replace the patched umrdp.dll — re-run setup-server.ps1 or patch-umrdp.py after updates.