Once upon a time (circa 1999), RS232 was the primary mechanism for communicating and updating firmware in most computer systems. This means that we had to make a bunch of cables and rather than soldering pin the techie crew often used these modular adapters as the pinout needed for various installations varied.
ADM 9F8 GR - RJ45 to db9 fem The following is for the D-Sub-RJ-45 Modular Adapter
1 - blu
2 - org
3 - blk
4 - red
5 - grn
6 - yel
7 - brn
8 - wht