What is the purpose of applsyspub/pub and guest/oracle?

1. APPLSYSPUB/PUB

APPLSYSPUB is a public schema that grants access to the Oracle applications initial sign-on forms. The default password is PUB. The OS environment variable GWYUID in .env is for this. There is no need to change it.

APPLYSYPUB has no data objects, only synonyms to APPS.

SYNONYM_NAME OWNER OBJECT_NAME OBJECT_OWNER
BSC_SECURITY_PKG APPLSYSPUB BSC_SECURITY_PKG APPS
FND_APPLICATION APPLSYSPUB FND_APPLICATION APPS
FND_APPLICATION_TL APPLSYSPUB FND_APPLICATION_TL APPS
FND_APPLICATION_VL APPLSYSPUB FND_APPLICATION_VL APPS
FND_DISCONNECTED APPLSYSPUB FND_DISCONNECTED APPS
FND_LANGUAGES_TL APPLSYSPUB FND_LANGUAGES_TL APPS
FND_LANGUAGES_VL APPLSYSPUB FND_LANGUAGES_VL APPS
FND_LOOKUPS APPLSYSPUB FND_LOOKUPS APPS
FND_MESSAGE APPLSYSPUB FND_MESSAGE APPS
FND_PRODUCT_GROUPS APPLSYSPUB FND_PRODUCT_GROUPS APPS
FND_PRODUCT_INSTALLATIONS
APPLSYSPUB FND_PRODUCT_INSTALLATIONS APPS
FND_PUB_MESSAGE APPLSYSPUB FND_PUB_MESSAGE APPS
FND_SECURITY_PKG APPLSYSPUB FND_SECURITY_PKG APPS
FND_SESSIONS APPLSYSPUB FND_SESSIONS APPS
FND_SIGNON APPLSYSPUB FND_SIGNON APPS
FND_UNSUCCESSFUL_LOGINS APPLSYSPUB FND_UNSUCCESSFUL_LOGINS APPS
FND_WEBFILEPUB APPLSYSPUB FND_WEBFILEPUB APPS
CSF_MD_ADM_BOUNDS APPLSYSPUB CSF_MD_ADM_BOUNDS CSF
CSF_MD_HYDROS APPLSYSPUB CSF_MD_HYDROS CSF
CSF_MD_LAND_USES APPLSYSPUB CSF_MD_LAND_USES CSF
CSF_MD_POIS APPLSYSPUB CSF_MD_POIS CSF
CSF_MD_RAIL_SEGS APPLSYSPUB CSF_MD_RAIL_SEGS CSF
CSF_MD_RD_SEGS APPLSYSPUB CSF_MD_RD_SEGS CSF

Above is from my PROD. Need to check some synonyms from CSF schema.

APPLSYSPUB is a gateway user and used for connection purposes. When you sign on to Oracle Applications, you initially connect to the public schema, APPLSYSPUB. Once your user name and password are verified, Oracle Applications connects your to the APPS schema and allows you to choose a responsibility. You can then use the professional interface or the HTML interface to access data that resides in a product schema.

APPLSYSPUB/PUB appears in contextfile, dbc file and env file. Dbc file and env file are populated with the value in contextfile.



2. GUEST/ORACLE

The application account GUEST is used by the foundation layers in order to establish user sessions where the user identity is not yet known. End users should not actually be logging into this account directly.

Some additional points:
2.A. GUEST User is used to connect to RDBMS to render the login page.
The name/password can be anything for GUEST user but it should be same in the .dbc file and Profile Option (Guest User Password).
Check the GUEST user information (name can be different according to your Instance)
a. Run following SQL:

SQL>select user_name, start_date, end_date from fnd_user where user_name = 'GUEST';

This should return one row, end_date should be NULL or in advance of today's date, and start_date should be before today's date.

b. Validate the GUEST username/password combinations from the DBC file.
Using the GUEST_USER_PWD value in the DBC file run the following sql:

SQL>select fnd_web_sec.validate_login('GUEST',' ') from dual ;

This should return Yes.

2.B. To set it permanently across the Applications, change the following parameters in _.xml and run autoconfig on the middle
tier:



GUEST
ORACLE


2.C. Use Note 443353.1 How To Successfully Change The Guest Password In E-Business Suite 11.5.10 and R12 to rectify the GUEST password change issue in an Oracle Supported way