mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-03-13 02:23:50 -05:00
15f097f399
In recent months I've had two requests from different people to build support into PuTTY for automatically handling complicated third-party auth protocols layered on top of keyboard-interactive - the kind of thing where you're asked to enter some auth response, and you have to refer to some external source like a web server to find out what the right response _is_, which is a pain to do by hand, so you'd prefer it to be automated in the SSH client. That seems like a reasonable thing for an end user to want, but I didn't think it was a good idea to build support for specific protocols of that kind directly into PuTTY, where there would no doubt be an ever-lengthening list, and maintenance needed on all of them. So instead, in collaboration with one of my correspondents, I've designed and implemented a protocol to be spoken between PuTTY and a plugin running as a subprocess. The plugin can opt to handle the keyboard-interactive authentication loop on behalf of the user, in which case PuTTY passes on all the INFO_REQUEST packets to it, and lets it make up responses. It can also ask questions of the user if necessary. The protocol spec is provided in a documentation appendix. The entire configuration for the end user consists of providing a full command line to use as the subprocess. In the contrib directory I've provided an example plugin written in Python. It gives a set of fixed responses suitable for getting through Uppity's made-up k-i system, because that was a reasonable thing I already had lying around to test against. But it also provides example code that someone else could pick up and insert their own live response-provider into the middle of, assuming they were happy with it being in Python.