Hi Micio82,
for the working driver i also use an tcp/ip stack(embosIP) and an operating system(embOS) from the Segger company. Due to their regulations i'm not allowed to send this stuff to the public. But what might help you is the light weight tcp/ip stack with an altera driver (lwip). You should have a look to this thread
http://www.alteraforum.com/forum/showthread.php?p=93638#post93638 and here you can get the driver
http://lwip.wikia.com/wiki/available_device_drivers#lwip_1.3.2 this driver example helped me a lot, hope it does the same for you.
If i find a little time, i might also copy some stuff together and post it here, but at the moment we have an urgent project.
Greeting, Oberon