pyusbip

pyusbip is a userspace USBIP server implementation based on python-libusb1. (In USBIP, the 'server' has the physical USB device attached, and the 'client' has only a network cable attached; i.e., you run this if you have a USB device attached to your local machine that you'd like to be able to use on a different computer.)

It has been tested (for small values of "tested") on Mac OS X; it is, at least, sufficient to forward a Lattice MachXO3 eval kit to the Lattice programmer software.

Usage instructions

Following is a rough recipe for getting started with forwarding a USB device using pyusbip.

• Make sure that you have python-libusb1 installed: pip install libusb1.
• As necessary on your platform, give yourself permission to access the USB device.
• Launch pyusbip: python3 pyusbip.py
• Forward the port to another machine: ssh you@target_machine -C -R 3240:127.0.0.1:3240
• Find the device you want: sudo usbip list -r 127.0.0.1
• Attach the device you want: sudo usbip attach -r 127.0.0.1 -b 20-4
• Enjoy!

Limitations

pyusbip has many limitations. Much of the protocol is unimplemented; pyusbip simply disconnects a device and drops a connection if it trips on that. In some cases, protocol violations in USBIP can cause the Linux kernel's entire USB stack to crash (!); for instance, if pyusbip gets stuck transmitting half of a response URB, you may need to reboot the remote end before it'll come back to life. Following is a list of known limitations in pyusbip:

• pyusbip gives up on a device if it can't claim all interfaces, rather than failing URBs with -EPERM or some such. (This is a problem when exporting, say, a ST-Link board that also has a mass storage device, from OS X.)
• pyusbip's control traffic is synchronous.
• pyusbip does not keep track of what type of endpoint it's talking to, and as such, always sends bulk requests, even to interrupt or isochronous endpoints.
• pyusbip does not implement isochronous endpoints at all.
• Error handling usually results in forcing a device disconnect, rather than doing anything reasonable.
• UNLINK requests may send a spurious URB reply, which could confuse some clients.
• Comments are ... sparse.
• Code architecture is suspicious.

Contact

pyusbip is unsupported. Please use the GitHub repository to submit patches. If you need to, you can contact the author.