Linux Headers

I assume what you want to do is to build a special software that needs a kernel driver. For everything else the headers present on the ReadyNAS should be sufficient. So, here's how to prepare a kernel tree (and in due course the header files) for building stuff that needs to work with the original kernel tree.

1) Get hold of the NETGEAR GPL sources for your firmware version from here -> https://kb.netgear.com/2649/NETGEAR-Open-Source-Code-for-Programmers-GPL

2) Unpack the file on the ReadyNAS (ideally you'll use the root account for that but preferrably NOT the root home directory. Some directory below /data will be fine

3) Copy the linux-kernel-* source directory for your architecture from the unpacked GPL archive to another place, say /data/kernel

4) Go to that directory and run "make clean && make && make install && make modules_install" (the last one is optional)

This should create all the symlinks within the /lib/modules/<your kernel version> that are needed for compiling software that needs access to the kernel sources.

Now, if I completely missed the point just let me know in more detail what you're trying to do and I'll see whether I can help you more.

-Stefan