Thunderbolt and USB4 host-to-host networking (ThunderboltIP / USB4NET)
Lets two computers connected by a Thunderbolt or USB4 cable talk to each other as if they were on a fast point-to-point Ethernet link. Apple introduced this as IP-over-Thunderbolt for Mac-to-Mac transfers, and the same scheme now works across Linux, macOS, and Windows on any Thunderbolt 3/4/5 or USB4 host.
recommendation
It should stay because the underlying hardware (Thunderbolt 3/4/5 and USB4) is still being sold new in 2025, the kernel admin guide still documents cross-OS host-to-host networking over a Thunderbolt cable, and the code is actively maintained with recent commits adding features like link settings, MAC address changes, and flow control. Deployment is niche rather than dead, and no other upstream driver covers the same use case.
repository signals
sources
- docs.kernel.org
Current kernel documentation still documents 'Networking over Thunderbolt cable', including Linux, Windows, and macOS interoperability via thunderbolt-net.
- support.apple.com
Apple still documents 'Use IP over Thunderbolt to connect Mac computers', indicating the peer-to-peer Thunderbolt networking use case remains supported on current Macs.
- intel.com
Intel markets Thunderbolt 5 as a current-generation shipping technology, so the underlying transport hardware is still sold new in 2025/2026.
- cateee.net
LKDDb shows CONFIG_USB4_NET present through current kernel series, with this driver living in drivers/net/thunderbolt for recent kernels.
codex reasoning notes (technical)
Real driver directory: Kconfig/Makefile plus net_device_ops in main.c. Local shell inspection showed active in-tree maintenance, with recent commits through 2026-01-19 (feature work and bug fixes such as link settings, MAC address changes, flow control), which argues against deprecation. I attempted lore-first evidence via shell `lei q`, but `lei` was unavailable in this environment; web searches for lore-specific threads returned no usable hits, so no direct lore URL for removal discussion was obtained. Cited URLs were obtained via web search (`docs.kernel.org`, Apple Support, Intel, LKDDb). The feature is not mass-market Ethernet, but it is still relevant on modern Thunderbolt/USB4 systems and remains documented for cross-OS host-to-host networking, so deployment is low rather than none. No natural upstream replacement covers the same Thunderbolt-cable host-to-host networking use case.