If you are getting a “ ORA-1017: invalid username/password; logon denied” when creating a database link, and you ensured to enter the correct password, you probably try it against a 11g database version. In this version is a new feature the “case sensitivity rules”. This statement worked from a 11g db to a 10g database, and threw a exception from 10g to 11g.
create database link testdblink
connect to TESTUSER identified by “testpw”
using ‘tns_for_test’;
Use double-quotes, and check these documents;
What Are the Oracle Database Built-in Password Protections?
http://download.oracle.com/docs/cd/B28359_01/network.111/b28531/authentication.htm#CHDBBGFG
Enabling or Disabling Password Case Sensitivity
http://download.oracle.com/docs/cd/B28359_01/network.111/b28531/authentication.htm#CHDJDCGI
