What Is SocketCAN?

SocketCAN is the CAN bus support built into the Linux kernel. It treats each CAN controller as a network interface, named can0, can1 and so on, and lets programs send and receive CAN frames through the same socket calls they would use for a network connection. It was contributed largely by Volkswagen Research and merged into the mainline kernel in version 2.6.25 in 2008.

Before SocketCAN, each CAN adapter came with its own driver and programming interface, so software written for one card had to be rewritten for another. SocketCAN gives Linux one standard way to use CAN: applications open a socket in the PF_CAN protocol family, and the same code works whichever hardware sits underneath, from a USB adapter to a CAN controller inside the processor. Our explainer on what CAN bus is covers the network itself.

SocketCAN slots CAN into the kernel’s networking layer. A device driver handles the CAN controller and presents it as a network device; the CAN protocol layer then offers several socket types to applications:

Because a CAN port is a network interface, it is configured with the standard ip tool from iproute2. The bit rate must match the rest of the bus, and the interface must be brought up before use. For a 500 kbit/s network, for example, the commands are ip link set can0 type can bitrate 500000 followed by ip link set can0 up. CAN FD needs a data bit rate as well, set with dbitrate and fd on.

The same tool shows error counters and the bus state, and a restart-ms setting lets the controller recover automatically if it goes bus-off after repeated errors. For testing without hardware, the vcan module creates a virtual CAN interface, vcan0, that software can talk to as if it were a real bus.

The can-utils package provides command-line tools that work with any SocketCAN interface. They are usually the first thing an engineer reaches for when bringing up a new CAN connection.

For application code, C programs use the socket API directly, and Python programs commonly use the python-can library, which has a SocketCAN back end.

Any CAN controller with a SocketCAN driver in the kernel can be used this way. That includes the CAN controllers built into many embedded processors, such as the controllers on NVIDIA Jetson modules supported in Linux for Tegra, SPI-connected CAN chips on carrier boards, and many USB and PCIe adapters. When choosing an adapter for Linux, check that its driver is in the mainline kernel or supplied by the maker, and whether it supports CAN FD.

Our CAN bus I/O modules include USB, mPCIe and PC/104 options for adding ports to a computer, and many in-vehicle computers have isolated CAN ports on board.

SocketCAN is how a Linux in-vehicle computer joins the vehicle network. It logs engine and body signals, reads J1939 data on trucks and machinery, and sends commands to equipment such as lifts or spreaders. In the refuse collection vehicle case study, vehicle signals are used alongside camera detection. It is also used on robots and AGVs, where CANopen drives and battery systems share a bus, and in test benches that simulate or record vehicle traffic. Because the interface is standard, the same logging or gateway software can move from a development PC with a USB adapter to an in-vehicle computer with onboard CAN without code changes.

We fit CAN ports and modules to Linux in-vehicle and edge computers as standard, install the drivers and check each interface with SocketCAN before the system ships. Tell us your bit rate, protocol and connectors, and we will specify the interface to match.