To compile those drivers, download the zipped file, then unzip it:
unzip 311lin71.zip
These drivers work with kernel 2.4, so if you are not running that, then this probably won’t work. Also, this is a beta driver, which means that it may be buggy even if it compiles and installs perfectly.
Then cd to that directory:
cd “fa311 beta driver for Linux7.1”
Everything else should be done as root user. In the directory, compile the module:
make clean
make
You need make, gcc, and a few other “developer tools” in order to do this successfully. There is a compiled module included with the zip file, compiled for 2.4.2. If you want to use it because you haven’t installed the tools to compile it or compilation fails, do not type the two make lines.
Then copy it to the modules directory:
cp -i natsemi.o /lib/modules/(kernel-number)/libkernel/drivers/net/natsemi.o
This will prompt if it is overwriting an older driver module. I would be a little conflicted about doing this. Replace the (kernel-number) with your appropriate kernel. In a clean installation, there should only be one kernel-number modules directory (since you only have one kernel installed).
Next, try to insert the module:
/sbin/modprobe natsemi
And hopefully it won’t give any errors. If it does, then try something else. Inserting it should hopefully allow you to configure the network on that interface, which should be found at /dev/eth0. I am not familiar with libranet, but hopefully it gives you some network configuration tool to make this simpler. I know RedHat does, I know Debian does, I know Slackware does. Also, libranet probably has some features to automatically insert modules into the kernel at bootup. You obviously want to do this before it tries to configure the network.