ORA-28545 - Unable To Connect To Remote Database Using Database Link After Ap...

刘泽宇

现象：
After apply the latest Windows Bundle Patch 18c or 19c, oracle database database link to remote Oracle Database Gateway stopped working with below error.


SQL> select count(*) from <table_name>@<dblink>;
select count(*) from <table_name>@<dblink>
  *
ERROR at line 1:
ORA-28545: error diagnosed by Net8 when connecting to an agent
Unable to retrieve text of NETWORK/NCR message 65535
ORA-02063: preceding 2 lines from <DBLINK>


原因：
Using NTS authentication service in the sqlnet.ora
SQLNET.AUTHENTICATION_SERVICES= (NTS)


When using NTS, between Database client and server, if Kerberos authentication is not possible, it will fall back to NTLM. In the past, NTLM is allowed by default, and that's why this behavior was not obvious for the customers.

After some security fixes, now NTLM is disabled by default. If the connection between Database client and server is not capable of doing Kerberos, it will not be able to fall back to NTLM.

This is intentional, and customers need to be aware of the fact that they are going to use NTLM, and explicit configuration needs to be done to enable NTLM.

Once customers specify NO_NTLM=FALSE, it will be able to fall back to NTLM from Kerberos if required.



处理方法：
- Add below parameter to the Oracle database sqlnet.ora file. The new parameter is a requirement from latest Windows Bundle Patch.

SQLNET.NO_NTLM=FALSE


- Stop/Start the oracle services