How-to make your own Ethernet "splitter"

Step 2 Crimp the RJ45 Plug to the ethernet cable

...using the following wiring scheme:

1 White/Orange
2 Orange
3 White/Green
4 Blue
5 White/Blue
6 Green
7 White/Brown
8 Brown

Taken from the excellent Hardware Book: www.hardwarebook.net/cable/network/ethernet10basetstraightthru.html