We have a windows file storage (don't ask) and now I want to rsync with the machine from Windows, Mac and Linux.

So I installed freeSSHd (login shell is set to C:/cygwin64/bin/sh.exe), set up certificates and testing from Linux the test.dat has 0 bytes:

ssh myuser@winmachinename "C:/cygwin64/bin/true.exe" > test.dat

Even double checking with actual output works fine:

ssh myuser@winmachinename "C:/cygwin64/bin/ls.exe" > test.dat

Now, when I call rsync:

rsync --progress -avz -e ssh myuser@winmachinename:/c/Users ~/test

it fails with:

protocol version mismatch -- is your shell clean?
(see the rsync man page for an explanation)
rsync error: protocol incompatibility (code 2) at compat.c(174) [Receiver=3.1.0]

As far as reading the docs, this should not happen, when the first test is successful!?

I am by now out of ideas - any recommendations how to debug this?

EDIT:

| OS            | rsync version                             |
|:--------------|:------------------------------------------|               
| Windows       | rsync  version 3.0.9  protocol version 30 |
| Linux         | rsync  version 3.1.0  protocol version 31 |