Forwarding IP Packets

Hi,

Is there a non intrusive way to forward IP packets arriving at server with public IP address x.x.x.x and port number xx to a server with public IP address y.y.y.y and port number yy?
I don’t merely need to redirect the packets from one server to another, the user space applications running on both these servers needs to access the information in the packets at the same time.
I understand that I can write a user space application on server with IP address x.x.x.x and thereafter send it to server with address y.y.y.y, however that will be at the cost of a performance hit.

Looking forward to your response.

Brijraj