| File | Description |
| snmpusmtable.c | To handle the requests from the manager for the module usmusertable. |
| usmparams.c | Handler file for USM counters (usmUnSupportedSecLevel, usmNotInTimeWindow, usmUnknowEngineId, usmUnknownUserName, usmWrongDigest and usmDecryptionError). |
| usmuser.c | To handle the requests from the manager for the module usmuser. |
| usmutils.c | This file will contain utils methods related to USM(User based secutiry model). |