Ethernut 4.8.9 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. This free software was originally created by egnite GmbH.
The following version: 4.8 is the most frequently downloaded one by the program users. We cannot guarantee that the program is safe to download, so we recommend checking it with any free antivirus software before launching. The program lies within Internet & Network Tools, more precisely Network Tools.
From the developer:
Ethernut is a software project specially designed for building tiny Embedded Ethernet Devices. This software has priority based, cooperative multithreading, it is scalable from minimal low power to high performance targets, TCP/IP stack for trouble-free Intranet and Internet connections and much more
You may want to check out more software, such as Plesk for Windows, FRITZ! or JaSFtp7, which might be similar to Ethernut.