I want to connect two computers directly and use the USB 3 or USB-C connection as a normal network link, ideally without needing special file-transfer software. USB Ethernet adapters already exist, so I wondered whether a USB-to-USB cable could contain the necessary hardware and present itself to both computers as an Ethernet adapter. I know about USB bridge cables that support file transfers through proprietary software, and IP over Thunderbolt, but one of the computers does not support Thunderbolt. Is there a USB 3 or USB-C cable or adapter that can provide a standard network connection between the two machines?
4 Answers
A plain USB cable cannot do this because both computers are normally USB hosts. You need active electronics in the middle and drivers or a supported USB networking mode on both systems. The existing USB transfer cables work by including a bridge chip and using special software; they are not simply USB wires carrying Ethernet frames.
The older LapLink-style and modern USB transfer cables are the closest products, but they contain a bridge chip and depend on software. They are intended for migration or file copying rather than exposing a regular network interface, so they do not provide the universal cable-only solution you are looking for.
USB networking is possible in principle using protocols such as USB Ethernet gadget or CDC networking, but one side has to operate as a USB device and the host operating systems must support the relevant protocol. Two ordinary computers connected directly over USB 3 generally do not automatically negotiate this, so custom drivers or configuration would be required.
The practical solution is to use two USB-C-to-Ethernet adapters and connect them with a regular Ethernet cable. The adapters handle the conversion and appear as normal network interfaces to the operating systems. Even if there is some conversion overhead, it is generally the simplest and most compatible approach, and you can use faster 2.5G or 10G adapters if needed.
For a direct connection, a normal Ethernet cable is usually fine with modern adapters because they support auto-negotiation. A crossover cable is rarely necessary.
USB-C only describes the connector and wiring options, not a built-in host-to-host networking protocol. USB4 and Thunderbolt can tunnel networking in some cases, but that depends on hardware support and is different from ordinary USB 3.