Create a certificate

$ mkdir /u01/app/wallet

$ cd /u01/app/wallet

$ orapki wallet create -wallet . -auto_login -pwd welcome1

$ orapki wallet add -wallet . -dn CN=’Server.FQDN’ -keysize 512 -self_signed -validity 5000 -pwd welcome1

$ chmod 644 /u01/app/wallet/*

$ vi $ORACLE_HOME/network/admin/sqlnet.ora

# sqlnet.ora Network Configuration File: /u01/app/oracle/product/12.2.0/dbname/network/admin/sqlnet.ora
# Generated by Oracle configuration tools.

NAMES.DIRECTORY_PATH= (TNSNAMES, ONAMES, HOSTNAME)

SSL_VERSION = 0

SSL_CLIENT_AUTHENTICATION = FALSE

SQLNET.ALLOWED_LOGON_VERSION_SERVER = 8

WALLET_LOCATION =
(SOURCE =
(METHOD = FILE)
(METHOD_DATA =
(DIRECTORY = /u01/app/wallet)
)
)

ADR_BASE = /u01/app/oracle

$ vi $ORACLE_HOME/network/admin/listener.ora

# listener.ora Network Configuration File: /u01/app/oracle/product/12.2.0/dbname/network/admin/listener.ora
# Generated by Oracle configuration tools.

LISTENER_DBNAME =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = host.FQDN)(PORT = 25513))
)
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC25513))
)
)

SSL_CLIENT_AUTHENTICATION = FALSE

ADR_BASE_LISTENER_CFEDWH = /u01/app/oracle

WALLET_LOCATION =
(SOURCE =
(METHOD = FILE)
(METHOD_DATA =
(DIRECTORY = /u01/app/wallet)
)
)

$ vi $ORACLE_HOME/network/admin/tnsnames.ora

CFEDWH_s =

(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCPS)(HOST = host.FQDN)(PORT = 5500))
(CONNECT_DATA =
(SERVICE_NAME = db_service)
)
)