From The Management Utility - Oki C5550 User Manual

....F
ROM THE MANAGEMENT UTILITY
If you have not already done so, install the MFP Network Setup
Tool as described in
NOTE
The Administrative Settings are blocked by a password. It is
recommended that the system administrator creates a new
one since the machine is shipped without a specific password.
"MFP network setup tool" on page
Configuring your machine.... > 38
22.