Using database links with ADB-S without wallet

In the previous post, we saw about how to setup a database link connecting two different ADB-S accessible over the public endpoint using wallet in place. In this blogpost we will see about how to establish database link connecting two different ADB-S accessible over the public endpoint without wallet in place.
 
On the target ADB details page, under Network, click Edit in the Mutual TLS (mTLS) authentication field & change the value to allow TLS Authentication by deselecting Require mutual TLS (mTLS) authentication and click update, the ADB lifecycle state changes to updating and post that mutual TLS (mTLS) authentication field changes to show Not required. 

 

To create database link to a public target, the target database must be accessible, some database including ADB limit access (using ACL), so make sure to enable target database to allow access from source database using database link, if we limit access with ACL, then make sure to find the outbound IP address of source database and allow that IP address to connect to your target database. By adding outbound IP address of source database to ACL of the target database.
 
On the source database
 
demo-user@ATP19C> select jt.*
  2  from v$pdbs, json_table( cloud_identity,'$.OUTBOUND_IP_ADDRESS[*]'
  3      columns( outbound_ips varchar2(20) path '$') ) jt;
 
OUTBOUND_IPS
----------------
150.136.133.92
 
On the target Autonomous database 
 

 
Then create credentials to access the target database, the username and the password for the dbms_cloud.create_credentials are the credentials to the target database.
 
demo-user@ATP19C> begin
  2     dbms_cloud.create_credential(
  3             credential_name =>'DB_LINK_CRED',
  4             username =>'DEMO_USER',
  5             password=>'Good2go1!1234' );
  6  end;
  7  /
 
PL/SQL procedure successfully completed.
 
Then create the database link to the target database using DBMS_CLOUD_ADMIN package, like this
 
demo-user@ATP19C> begin
  2     dbms_cloud_admin.create_database_link(
  3             db_link_name => 'DB_LINK_TEST',
  4             hostname => 'adb.us-ashburn-1.oraclecloud.com',
  5             port => 1522,
  6             service_name => 'g26be7c92912cdb_atp21c_low.adb.oraclecloud.com',
  7             credential_name =>'DB_LINK_CRED',
  8             directory_name => null );
  9  end;
 10  /
 
PL/SQL procedure successfully completed.
 
demo-user@ATP19C> select * from dual@DB_LINK_TEST;
 
D
-
X
 
To create a database link with DBMS_CLOUD_ADMIN.CREATE_DATABASE_LINK to a target Autonomous Database on a public endpoint using a secure TCP connection without a wallet, the directory_name parameter must be NULL.
 
demo-user@ATP19C> select banner_full from v$version;
 
BANNER_FULL
------------------------------------------------------------------------
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.23.0.1.0
 
 
demo-user@ATP19C> select banner_full from v$version@db_link_test;
 
BANNER_FULL
------------------------------------------------------------------------
Oracle Database 21c Enterprise Edition Release 21.0.0.0.0 - Production
Version 21.3.0.0.0