sync netbsd drive with Windows 10

[Bob Bernstein <bob%fanatick.org@localhost>]

Request for Suggestions:

I am gathering what will ultimately be about 100G of files on my 
amd64 Netbsd (an old eMachine windows box itself) system's 
original HD.

That system as well as my Windows 10 (running off a NUC) are 
cat-5 wired into the LAN upstairs here in the house.

The NUC now has a WD 1TB "Passport" external USB drive attached 
to it.

What tools are suggested for keeping that external drive synched 
with the dir in play on the Netbsd machine?

Thank you

--
"...it is undesirable to believe a proposition when
there is no ground whatever for supposing it true."

                       Bertrand Russell (1928)