DB2 to require password each time I am using db2inst1 to connect to a database in DB2 which I have installed on my machine. Therefore, db2inst1 user does not require username/password authentication (borrows them from the OS). I would like to change that, and force every time a connection is initiated a username/password to be requested. 

More specifically, this is how the authentication configuration looks like:


  db2 get dbm cfg|grep -i auth


 GSS Plugin for Local Authorization    (LOCAL_GSSPLUGIN) = 
 Server Connection Authentication          (SRVCON_AUTH) = NOT_SPECIFIED
 Database manager authentication        (AUTHENTICATION) = CLIENT
 Alternate authentication           (ALTERNATE_AUTH_ENC) = NOT_SPECIFIED
 Cataloging allowed without authority   (CATALOG_NOAUTH) = NO
 Trusted client authentication          (TRUST_CLNTAUTH) = SERVER
 Bypass federated authentication            (FED_NOAUTH) = NO



  db2 connect to dbName


   Database Connection Information

   Database server        = DB2/LINUXX8664 10.1.0
   SQL authorization ID   = DB2INST1
   Local database alias   = DBNAME



  db2 connect to dbName user db2inst1 using password


   SQL1639N  The database server was unable to perform authentication because 
   security-related database manager files on the server do not have the required 
   operating system permissions.  SQLSTATE=08001


I have played with some authentication combinations for "AUTHENTICATION" and "TRUST_CLNTAUTH" without much luck.
I believe you want the following


AUTHENTICATION = CLIENT
TRUST_ALLCLNTS = NO
TRUST_CLNTAUTH = SERVER


As you have changed above, the AUTHENTICATION=CLIENT, will force the client to authenticate. (Which can still use the OS as noted above.)

TRUST_CLNTAUTH = SERVER will cause the client to send the user id and password to the server for authentication when they are provided in the connect statement. This still does not force the client to require the user name and password as it can get them from the OS. 

This is because DB2 will assume TRUST_ALLCLNTS as YES by default. This causes the server to assume all clients can be trusted and allow them to check against their respective OS's. So from what I know, to force the client to require a user name and password with the connect statement requires TRUST_ALLCLNTS to be set to NO. This will cause the server to not trust them and force them to send the user id and password to the server to authenticate against it.