Yun- can I not use Ethernet* classes with the ethernet port like an Ethershield?

I'd like to use the wifi for the regular yun bridge/rest functionality.

I'd like to then use the ethernet port for internal communication with another arduino (yun or otherwise) via udp.

So this would require me to run the non-bridge ethernet stuff on that port.

But the yun seems to allocate both wifi AND the ethernet port to the linux side.

Is there a way to get the yun to use the ethernet port as a regular ethernet shield so that I can use those classes?

Hi, welcome to the forum.

The 'normal' Ethernet library was developed for the W5100 chip. The W5100 chip is accessed via the SPI bus.

The Yun is like an Arduino Leonardo (no ethernet) plus a wifi/ethernet/linux/OpenWRT module. That means that everything between the "Leonardo" and the wifi/linux module has to go via the Bridge.
The Bridge library is large, and can do many things : http://www.arduino.cc/en/Reference/YunBridgeLibrary
The libraries are not the same, so you can't use a regular Ethernet sketch for the Yun.