This modular adapter converts from a DB9 female to an RJ45 female socket jack for serial terminal access to networking equipment such as Cisco.

The pin outs are as follows:
DB9 Pin. RJ45 Pin
1 Red      4 
2 Black.   3
3 Yellow   6
4 Brown   7
5 Green   5
6 Orange 2
7 White    8
8 Blue      1
9 No Connection