usbredir: A protocol for sending USB device traffic over a network connection

Original Article ↗ Hacker News Discussion ↗

usbredir vs USB/IP and SPICE integration

  • Several comments compare usbredir to USB/IP.
  • Main distinction raised: usbredir ties into the SPICE protocol used by QEMU/libvirt, enabling USB redirection into VMs “without guest cooperation” (no USB/IP support needed inside the guest OS).
  • USB/IP is noted as mature, in-kernel on Linux since 3.17, and with Windows/macOS support (though macOS can only export, not import, devices).
  • Some uncertainty over performance characteristics (latency, throughput) and suitability for high‑bandwidth or low‑latency devices (mice, webcams, displays, storage).

Gaming and Steam Deck controller forwarding

  • One thread explores forwarding Steam Deck controls over USB as a proper USB device to another Linux gaming rig, ideally fooling Steam Input into thinking it’s a real Deck.
  • Suggestions include USB gadget mode, Linux’s raw-gadget support, and a project (GadgetDeck), but current solutions seem incomplete or clunky.
  • Debate over wireless latency:
    • One side claims Bluetooth/Wi‑Fi introduce “too much” latency for many games.
    • Others counter that modern wireless gaming mice can be near‑wired in latency, but note that most use proprietary RF, not Bluetooth; Bluetooth’s lower polling rate is considered worse for fast swipes.

Alternative models: Plan 9, 9P, and gadget modes

  • Plan 9 users mention simply importing /dev/usb over 9P to access remote USB.
  • Linux has 9P filesystem support, and kernel raw-gadget is cited as a generic way to proxy USB devices.
  • Steam Deck is said to support gadget mode, making direct USB device emulation at least theoretically possible.

Wireless USB history and security

  • Multiple comments recall Wireless USB products (hubs/dongles) from ~2006–2009.
  • It allowed transparent wireless USB connections but suffered from high cost, distance-related speed drops, UWB regulatory constraints, and limited device support.
  • Encryption existed but its strength and security implications are debated; some see attack scenarios as plausible but low‑probability in consumer settings.

Existing USB‑over‑network tools and deployments

  • VirtualHere is highlighted with large‑scale use on thousands of Raspberry Pis, forwarding diverse USB devices to cloud machines over VPN, especially when using Ethernet (not Wi‑Fi) for low latency.
  • Licensing (per‑server, non‑transferable, ~$49) sparks debate:
    • Critics dislike hardware‑bound licensing and cost at scale.
    • Defenders argue cost is reasonable versus hiring developers and benefits from active, long‑term maintenance.
  • Other tools mentioned: usbip/usbipd (including in WSL2), proprietary USB‑over‑network software, VMware Fusion/ESXi USB forwarding, and Apple’s old “Remote Disc”.

Use cases and practical concerns

  • Reported or proposed uses: remote debugging (ADB over RDP), VDI/home hypervisors with GPU passthrough and game streaming, observatory setups over long Ethernet runs, and remote access to specialized hardware (medical, gauges, scanners, dongles).
  • Latency, reliability, and OS driver issues (e.g., unsigned Windows drivers for USB/IP) are recurring concerns.
  • One anecdote notes learning USB cable length limits the hard way by splicing USB onto Ethernet cabling, likely miswiring and damaging hardware.