These BF1942 v1.612 Windows server executables display keyhashes, opposite to the server executable released with BF1942 Origin download. Besides that, they include security fixes and maximum players limit raised. Read included .nfo file for details.
BF1942_w32ded-1.612-keyhash.zip, this only allows BF1942 v1.612 (Origin) players to connect to the server.
BF1942_w32ded-1.612-keyhash_all_clients.zip, accepts all BF1942 client versions - v1.6, v1.61 and v1.612.