10 Configuring and Administering Oracle Connection Manager

Oracle Connection Manager is a proxy server that forwards connection requests to databases or other proxy servers. It operates at the session level, and usually resides on a computer separate from the database server and client computers.

Oracle Connection Manager is available for installation with Oracle Database Enterprise Edition. It is a custom installation option on the client system. Starting with Oracle Database Client 23ai, Oracle Connection Manager is available as an image file for installation and configuration. Refer to your platform-specific Oracle Database installation guide for additional information.

• Setting Up Oracle Connection Manager
  In order to set up Oracle Connection Manager, you must configure the proxy server, database, and clients.
• Configuring Oracle Connection Manager in Traffic Director Mode
  Oracle Connection Manager in Traffic Director Mode is a proxy that is placed between the database clients and the database instances.
• Configuring Oracle Connection Manager in Tunneling Mode for Reverse Connection
  Oracle Connection Manager in tunnelling mode establishes tunnel connections between server CMAN and client CMAN. Clients can make reverse connections over tunnels by connecting to server cman.
• Using Oracle Connection Manager as a Bridge for IPv4 and IPv6
  In some database connection environments, a client and database may use different versions of the IP protocol so that complete connectivity does not exist. In this case, at least two hops in the connection use different versions of the IP protocol.
• Using Oracle Connection Manager to Prevent Denial-of-Service Attacks
  You can enforce a limit on the number of client connections that Oracle Connection Manager (CMAN) can handle from an IP address in a specific time interval.
• Starting and Stopping Oracle Connection Manager
  After configuring Oracle Connection Manager, you can start and administer it using the Oracle Connection Manager Control (CMCTL) utility.
• About CMCTL REST Interface
  CMCTL REST interface helps you manage Oracle Connection Manager (Oracle CMAN) instance from remote machines using REST interface. A client that supports HTTPS can issue CMCTL equivalent commands. Each REST API call must have WWW-Authenticate HTTPS header with Basic authentication method.
• Migrating CMAN Sessions During Patching
  You can migrate the established client/server sessions from one Oracle Connection Manager (CMAN) instance to another Oracle CMAN instance during a planned upgrade or patching of Oracle CMAN with zero downtime.
• Oracle Connection Manager Enhancements
  Oracle Connection Manager proxies and screens request for Oracle Database Server.

10.1 Setting Up Oracle Connection Manager

In order to set up Oracle Connection Manager, you must configure the proxy server, database, and clients.

• About the cman.ora File
  You can set parameters in the cman.ora file to configure the computer that hosts Oracle Connection Manager.
• Configuring the cman.ora file for the Oracle Connection Manager Host
  
• Configuring Transport Layer Security on Oracle Connection Manager
  Create a wallet on the Oracle Connection Manager (CMAN) server, and then specify the TCP/IP with Transport Layer Security (TLS) listening endpoint and wallet location in the cman.ora file.
• Enabling Access Control
  
• Configuring Clients for Oracle Connection Manager
  
• Configuring the Oracle Database Server for Oracle Connection Manager
  

10.1.1 About the cman.ora File

You can set parameters in the cman.ora file to configure the computer that hosts Oracle Connection Manager.

The cman.ora file resides on the computer that hosts Oracle Connection Manager, and is located in the ORACLE_BASE_HOME/network/admin directory. If the cman.ora file is not present in the ORACLE_BASE_HOME/network/admin directory, then look for the file in ORACLE_HOME/network/admin directory.Oracle Connection Manager will not start if the cman.ora file does not exist. This file includes the following components:

• Listening endpoint
• Access control rule list
• Parameter list

Each Oracle Connection Manager configuration is encapsulated within a single name-value (NV) string, which consists of the preceding components.

One computer can host any number of Oracle Connection Managers, each with its own entry in the cman.ora file. When defining more than one Oracle Connection Manager in the file, you can assign a default by giving only one a fully qualified host name.

You can specify multiple rules for both client and Oracle Connection Manager Control utility (CMCTL) connections. The following guidelines apply when making changes:

• You must enter at least one rule for client connections and one rule for CMCTL connections. Omitting a rule results in the rejection of all connections for the rule type omitted.
• Oracle Connection Manager does not support wildcards for partial IP addresses. If you use a wildcard, then use it in place of a full IP address. The IP address of the client may be, for example, (SRV=*).
• Oracle Connection Manager supports only the /nn notation for subnet addresses. In Example 10-1, in the first rule, /24 represents a subnet mask that comprises 24 left-most bits. Only the first 24 bits in the client's IP address are compared with the IP address in the rule.

Note:

Oracle Connection Manager supports IPv6 addressing. See "Using Oracle Connection Manager as a Bridge for IPv4 and IPv6".

Example 10-1 shows a cman.ora file that contains a configuration entry for an Oracle Connection Manager called CMAN1.

Example 10-1 Sample cman.ora File

CMAN1=
  (CONFIGURATION=
    (ADDRESS=(PROTOCOL=tcp)(HOST=proxysvr)(PORT=1521))
    (RULE_LIST=
      (RULE=(SRC=192.0.2.32/24)(DST=sales-server)(SRV=*)(ACT=accept)
        (ACTION_LIST=(AUT=on)(MCT=120)(MIT=30)))
      (RULE=(SRC=192.0.2.32)(DST=proxysvr)(SRV=cmon)(ACT=accept)))
    (PARAMETER_LIST=
      (MAX_GATEWAY_PROCESSES=8)
      (MIN_GATEWAY_PROCESSSES=3)))
       

Example 10-1 shows the following rules:

• In the first rule in the example, the following parameters are set:
  • SRC=192.0.2.32/24 is for client connections. It designates the IP address of the client, or source.
  • DST=sales-server designates the destination host name. The ACT parameter specifies the action, that is, accept, reject, or drop. The ACTION_LIST parameter sets attributes for a connection if it is accepted, enabling you to override default parameter settings on a connection-by-connection basis.
• In the second rule, the following parameters are set:
  • SRC=192.0.2.32 and DST=proxysvr represent the same server, indicating that Oracle Connection Manager and CMCTL must reside on the same computer.

  See Also:

  "Enabling Access Control"

Table 10-1 describes the rule-level parameters in the cman.ora file.

Table 10-1 Rule-Level Parameters in cman.ora File

Parameter	Description
SRC	The source host name or IP address of the client. The IP address can be a subnet, such as 192.0.2.62/24.
DST	The destination host name or IP address of the database server. The IP address can be a subnet, such as 192.0.2.62/24.
SRV	The service name of the Oracle database obtained from the SERVICE_NAMES parameter in the initialization parameter file (init.ora). The service name is given by the client as part of the connect descriptor when connecting to the listener. This service name is compared to the service name specified in the rule list.
ACT	To accept, reject, or drop incoming requests based on the preceding three parameters.

You can define multiple rules in the RULE_LIST. The action (ACT) in the first matched RULE is applied to the connection request. If no rules are defined, then all connections are rejected.

In the following example, client computer client1-pc is denied access to the service sales.us.example.com, but client 192.0.2.45 is granted access to the service db1.

(RULE_LIST=
  (RULE=(SRC=client1-pc)(DST=sales-server)(SRV=sales.us.example.com)(ACT=reject))
  (RULE=(SRC=192.0.2.45)(DST=192.0.2.200)(SRV=db1)(ACT=accept)))

See Also:

Oracle Database Net Services Reference for additional information about Oracle Connection Manager parameters

10.1.2 Configuring the cman.ora file for the Oracle Connection Manager Host

You make changes to the cman.ora file manually. The following procedure describes how to set parameters in the cman.ora file:

1. Navigate to the cman.ora file in the ORACLE_BASE_HOME/network/admin directory.

   If the cman.ora file is not present in the ORACLE_BASE_HOME/network/admin directory, then look for the file in ORACLE_HOME/network/admin directory.

2. Open the cman.ora file with a text editor.
3. Configure the listening endpoint (ADDRESS).

   The listening endpoint specifies the protocol address for the Oracle Connection Manager listener. CMON, the Oracle Connection Manager monitoring process, uses this address to register information about gateway processes with the listener. The database uses the address to register service information at the Oracle Connection Manager node.

   The Oracle Connection Manager listener always listens on the TCP/IP protocol.

   (ADDRESS=(PROTOCOL=tcp)(HOST=proxysvr)(PORT=1521))

   Note:

   Oracle Connection Manager can connect to the database using protocols such as TCP/IP (version 4 and version 6). Starting with Oracle Database 12c release 2 (12.2), the TCPS protocol is also supported

4. Configure the access control rule list (RULE_LIST).

   The access control rule list specifies which connections are accepted, rejected, or dropped by the listener.

5. Configure the parameter list (PARAMETER_LIST).

   The parameter list sets attributes for an Oracle Connection Manager. Parameters take the following forms:

   • If global, then the parameter applies to all Oracle Connection Manager connections unless a rule-level parameter overrides it. To change a global parameter default setting, enter it into the PARAMETER_LIST with an allowable value.
   • If a rule-level parameter is enabled in the ACTION_LIST section of the RULE_LIST, then it applies only to connections specified by the rule. It overrides its global counterpart.

10.1.3 Configuring Transport Layer Security on Oracle Connection Manager

Create a wallet on the Oracle Connection Manager (CMAN) server, and then specify the TCP/IP with Transport Layer Security (TLS) listening endpoint and wallet location in the cman.ora file.

Note:

Starting with Oracle Database 23ai, the Oracle Wallet Manager (OWM) is desupported.

Oracle recommends using the orapki command line tool to replace OWM.

1. Confirm that a CMAN wallet has been created and that it has a certificate:
   1. Log in to the Oracle Connection Manager server where the CMAN wallet resides.
   2. Run the following command using the orapki command-line tool:

      orapki wallet display -wallet wallet_location

      Where, wallet_location is the path to the directory where the wallet is stored.

      If your wallet directory contains the cwallet.sso file (auto-login wallet) and it contains a user certificate, then this command displays a user certificate without asking for a password.

      Ensure that cwallet.sso contains a user certificate. If the wallet does not contain a user certificate, create a wallet that contains a user certificate, and then run the following command to create cwallet.sso in your wallet directory:

      orapki wallet create -wallet wallet_location -auto_login

2. In the cman.ora file, create a listening endpoint that uses TCP/IP with TLS (TCPS) and set the WALLET_LOCATION parameter to specify the wallet location on the CMAN side.

   For example, this is a sample cman.ora file configured with the TCPS protocol address and WALLET_LOCATION parameter settings:

   CMAN_1=
   	(CONFIGURATION=
       		(ADDRESS_LIST=
   		      (ADDRESS=(PROTOCOL=tcps)(HOST=proxysvr)(PORT=1522))
   		      (ADDRESS=(PROTOCOL=tcp)(HOST=proxysvr)(PORT=1523))
   		)
   		(RULE_LIST=
   		      (RULE=(SRC=*)(DST=*)(SRV=*)(ACT=accept))
   		)
       		(PARAMETER_LIST=
   		      (MAX_GATEWAY_PROCESSES=8)
   		      (MIN_GATEWAY_PROCESSSES=3)
       		)
   	 )
   WALLET_LOCATION= 
   	(SOURCE=
   		(METHOD=File)
   		(METHOD_DATA=
   			(DIRECTORY=wallet_location)
   	  	)
   	)
   SQLNET.WALLET_OVERRIDE = TRUE

   Note:

   The parameter WALLET_LOCATION is deprecated for use with Oracle Database 23ai for the Oracle Database server. It is not deprecated for use with the Oracle Database client.

   For Oracle Database server, Oracle recommends that you use the WALLET_ROOT system parameter instead of using WALLET_LOCATION.

10.1.4 Enabling Access Control

Use the RULE_LIST parameter to control client access to designated database servers in a TCP/IP environment. By entering filtering rules under this parameter, you can allow or restrict specific clients access to a database server.

The following procedure describes how to configure access control:

1. Open the cman.ora file with a text editor.

2. Update the RULE_LIST parameter using the following format:

          (RULE_LIST=
           (RULE=(SRC=source_host) 
                 (DST=destination_host) 
                 (SRV=service) 
                 (ACT=accept | reject | drop)))
   

   See Also:

   Table 10-1

10.1.5 Configuring Clients for Oracle Connection Manager

To route clients to the database server through Oracle Connection Manager, configure the tnsnames.ora file with a connect descriptor that specifies the protocol address of Oracle Connection Manager. This address enables clients to connect to the Oracle Connection Manager computer. The connect descriptor looks similar to the following:

sales=
  (DESCRIPTION=
    (ADDRESS=
      (PROTOCOL=tcp)
      (HOST=cman-pc)
      (PORT=1521))
    (CONNECT_DATA=
      (SERVICE_NAME=example.com)))

The following procedure describes how to configure a protocol address for Oracle Connection Manager:

1. Start Oracle Net Manager.

   See Also:

   "Using Oracle Net Manager to Configure Oracle Net Services"

2. In the navigator pane, select Service Naming from Directory or Local menus.

3. Click the plus sign (+) on the toolbar, or select Create from the Edit menu.

   The Welcome page of the Net Service Name wizard appears.

4. Enter a name in the Net Service Name field.

5. Click Next.

   The Protocol page appears.

6. Select the TCP/IP protocol for Oracle Connection Manager.

7. Click Next.

   The Protocol Settings page appears.

8. Specify the Oracle Connection Manager port and protocol. The default port number for Oracle Connection Manager is 1521, and the protocol is TCP/IP.

   See Also:

   Oracle Database Net Services Reference for protocol parameter settings

9. Click Next.

   The Service page appears.

10. Enter a service name in the Service Name field, and then select the connection type.

    See Also:

    "About Connect Descriptors" for additional information about setting the service name string

11. Click Next.

    Note:

    Do not click Test, because a connection cannot be tested at this point.

12. Click Finish to save your configuration and close the Net Service Name wizard.

    The new network service name and the Oracle Connection Manager protocol address is added to the Service Naming folder.

10.1.6 Configuring the Oracle Database Server for Oracle Connection Manager

Configuring the database server involves registering database information remotely with Oracle Connection Manager and, optionally, configuring the server for multiplexing.

Note:

If the database that you want to register with Oracle Connection Manager is located on a remote node, then you must configure the cman.ora parameter VALID_NODE_CHECKING_REGISTRATION to allow remote registration.

• Configuring Service Registration for Use with Oracle Connection Manager
  
• Enabling Session Multiplexing for Oracle Connection Manager
  

10.1.6.1 Configuring Service Registration for Use with Oracle Connection Manager

To enable the database server to communicate with Oracle Connection Manager, the tnsnames.ora file must include the service name entry, and the initialization parameter file (init.ora) must contain a descriptor that specifies the listening address of Oracle Connection Manager. The following procedure describes how to configure service registration:

1. Resolve the Oracle Connection Manager alias to a service name entry in the tnsnames.ora file as follows:

   cman_listener_address =
     (DESCRIPTION=
       (ADDRESS_LIST=
         (ADDRESS=(PROTOCL=tcp) (HOST=proxy_server_name)( PORT=1521))))
   

   For example, the alias listener_cman would be resolved to the following entry in the tnsnames.ora file:

   listener_cman=
    (DESCRIPTION=
     (ADDRESS_LIST=
      (ADDRESS=(PROTOCOL=tcp)(HOST=proxyserver1)(PORT=1521))))
   

2. Specify an alias for Oracle Connection Manager in the init.ora file as follows. This alias is the one specified in the tnsnames.ora file in step 1.

   REMOTE_LISTENER=cman_listener_address
   

   The alias must be specified because this address is TCP, port 1521 but it is not the default local listening address of TCP, port 1521 of the database server.

   For example, the alias for the Oracle Connection Manager listener running on host, proxyserver1, specified in step 1, might look like the following in the init.ora file:

   REMOTE_LISTENER=listener_cman
   

3. Configure REGISTRATION_INVITED_NODES in cman.ora if the database resides on a remote node. For example:

   (registration_invited_nodes=sales.us.example.com,10.245.129.60)

4. After the initialization parameter file is configured with the alias of Oracle Connection Manager, the Listener Registration (LREG) process can register database information with the Oracle Connection Manager listener. Use the following command to register the change:

   SQL> ALTER SYSTEM REGISTER

See Also:

"Registering Information with a Remote Listener"

10.1.6.2 Enabling Session Multiplexing for Oracle Connection Manager

To enable Oracle Connection Manager to take advantage of session multiplexing, set the DISPATCHERS parameter in the initialization parameter file (init.ora) with the attributes PROTOCOL and MULTIPLEX, similar to the following:

DISPATCHERS="(PROTOCOL=tcp)(MULTIPLEX=on)"

Table 10-2 lists the parameters to set different levels of multiplexing.

Table 10-2 Session Multiplexing Parameters

Attribute	Description
PROTOCOL	The network protocol for which the dispatcher generates a listening endpoint.
MULTIPLEX	This parameter is used to enable session multiplexing, as follows: If 1, on, yes, true, or both is specified, then multiplexing is enabled for both incoming and outgoing network sessions. If in is specified, then multiplexing is enabled for incoming network sessions from the client. If out is specified, then multiplexing is enabled for outgoing network sessions. If 0, off, no, or false is specified, then multiplexing is disabled for both incoming and outgoing network sessions.

See Also:

• Configuring a Shared Server Architecture for additional information about configuring shared servers

• Oracle Database Net Services Reference for a complete list of parameters and their default and allowed values

10.2 Configuring Oracle Connection Manager in Traffic Director Mode

Oracle Connection Manager in Traffic Director Mode is a proxy that is placed between the database clients and the database instances.

• About Using Oracle Connection Manager in Traffic Director Mode
  Oracle Connection Manager in Traffic Director Mode is a proxy that is placed between supported database clients and database instances.
• Configuring cman.ora File for Oracle Connection Manager in Traffic Director Mode
  You can set up Oracle Connection Manager in Traffic Director Mode using the TDM=YES setting in the cman.ora file.
• Configuring a Wallet for Oracle Connection Manager in Traffic Director Mode Proxy Authentication
  Oracle Connection Manager in Traffic Director Mode connects to the databases using the wallet that must be configured with cman.ora file.
• Configuring Databases for Oracle Connection Manager in Traffic Director Mode Proxy Authentication
  
• Configuring Service Registration with Oracle Connection Manager in Traffic Director Mode
  
• Configuring Proxy Resident Connection Pooling in Oracle Connection Manager in Traffic Director Mode
  You can configure PRCP either for each database service or for an entire PDB. By default, PRCP is configured in the per-service mode.
• Configuring Oracle Connection Manager in Traffic Director Mode for Unplanned Events
  
• Configuring Oracle Connection Manager in Traffic Director Mode for Planned Down Events
  
• Configuring Oracle Connection Manager in Traffic Director Mode for Service Affinity
  Configure Oracle Connection Manager in Traffic Director Mode to modify the default load distribution mechanism for routing incoming connection requests.
• Configuring Transport Layer Security on Oracle Connection Manager in Traffic Director Mode
  Create a wallet on the Oracle Connection Manager in Traffic Director Mode server (CMAN-TDM), and then specify the TCP/IP with Transport Layer Security (TLS) listening endpoint and wallet location in the cman.ora file.
• Oracle Connection Manager in Traffic Director Mode Restrictions
  These features are not supported with Oracle Connection Manager in Traffic Director Mode (CMAN-TDM) for all drivers.

10.2.1 About Using Oracle Connection Manager in Traffic Director Mode

Oracle Connection Manager in Traffic Director Mode is a proxy that is placed between supported database clients and database instances.

A current database OCI client or supported older version OCI client (Oracle Database 11g Release 2 (11.2) and later) can connect to Oracle Connection Manager in Traffic Director Mode. Oracle Connection Manager in Traffic Director Mode provides improved high availability (HA) (planned and unplanned), connection multiplexing support, and load balancing. This feature also provides an inband client notification mechanism to deliver planned shutdown for Oracle Connection Manager (CMAN) down and service down events to the OCI client. Additional CMAN parameters must be specified in the cman.ora configuration file to configure Oracle Connection Manager in Traffic Director Mode.

To configure CMAN to act as an Oracle Connection Manager in Traffic Director Mode, new parameters such as tdm and tdm_threading_model must be added in the cman.ora configuration file. Oracle Connection Manager (CMAN) is the standard Oracle Net proxy for both Oracle RAC and non-RAC databases.

The databases that Oracle Connection Manager in Traffic Director Mode connects to must have a user, for example,tdm with the CONNECT THROUGH privilege granted to connect as application users. Oracle Connection Manager in Traffic Director Mode uses proxy authentication and connects as this user.

• Connection Modes
  Oracle Connection Manager in Traffic Director Mode supports pooled and non-pooled modes of operation.
• Performance and Security
  Oracle Connection Manager in Traffic Director Mode allows client connections to be routed to databases, providing high availability and connection multiplexing capabilities. It also supports enhanced security features, and provides zero application downtime for planned and unplanned database outages.
• Database Links
  Oracle Connection Manager in Traffic Director Mode supports database links, which extends high availability and failover to databases.
• Per-Service and Per-PDB Connection Pools
  You can configure CMAN-TDM to establish either per-service or per-PDB pooled connections.
• Implicit Connection Pooling
  Client applications that do not use an application connection pool can leverage connection pooling capabilities without making any application-level change or calling the pooling APIs.

10.2.1.1 Connection Modes

Oracle Connection Manager in Traffic Director Mode supports pooled and non-pooled modes of operation.

• Pooled connection mode:

  Supports applications using the following database client releases:

  • OCI and Open Source Drivers (11.2.0.4 and later)

  • JDBC (12.1 and later)

  • ODP.NET (12.2 and later) 

  In addition, applications must be Database Resident Connection Pool (DRCP) aware. This means specifying (SERVER=POOLED) in the application's connect string.

• Non-pooled connection (or dedicated) mode:

  Supports applications using database client releases 11.2.0.4 and later. In this mode, some capabilities such as connection multiplexing are not available. 

10.2.1.2 Performance and Security

Oracle Connection Manager in Traffic Director Mode allows client connections to be routed to databases, providing high availability and connection multiplexing capabilities. It also supports enhanced security features, and provides zero application downtime for planned and unplanned database outages.

Transparent Performance and Connection Multiplexing

• Statement caching, rows prefetching and result set caching are auto-enabled for all mode of operations.

• Database connection multiplexing (pooled mode only) using Proxy Resident Connection Pooling (PRCP, a proxy mode of Database Resident Connection Pooling). PRCP uses the Oracle Call Interface (OCI) Session Pooling feature.

  PRCP provides connection services for a large number of client connections that are routed using a connection pool, which comprises a fewer number of server connections to target databases. PRCP reduces connection load (connection memory usage) on the database tier, and provides runtime load balancing between database and Oracle Connection Manager in Traffic Director Mode.

High Availability

• Multiple Oracle Connection Manager in Traffic Director Mode instances: Applications get increased scalability through client-side connect time load balancing or with a load balancer (BIG-IP, NGINX, and others).

• Rolling upgrade of Oracle Connection Manager in Traffic Director Mode instances.

• Closure of existing connections from client to Oracle Connection Manager in Traffic Director Mode for planned outages.

• In-band notifications to Oracle Database release 18c and later clients. For earlier release clients, notifications are sent with the response of the current request.

Security and Isolation

• Database proxy supporting TCP/TCPS and protocol conversion.

• Firewall based on IP address, service name, and TLS wallets.

• Tenant isolation in a multitenant environment.

• Protection against denial-of-service and fuzzing attacks. 

• Secure tunneling of database traffic across on-premises database and Oracle Cloud.

Zero Application Downtime

• Planned database maintenance or pluggable database (PDB) relocation:

  • In a pooled mode, Oracle Connection Manager in Traffic Director Mode responds to Oracle Notification Service (ONS) events for planned outages and redirects work. The connections are drained from the pool on Oracle Connection Manager in Traffic Director Mode when the request completes. It also supports service relocation.

    Oracle Connection Manager in Traffic Director Mode responds to in-band notifications when a PDB is relocated, even when ONS is not configured (for server only).

  • In a non-pooled or dedicated mode, no request boundary information is received from the client. Oracle Connection Manager in Traffic Director Mode supports planned outage for many applications (as long as only simple session state and cursor state need to be preserved across the request or transaction boundaries). This involves the following:

    • Stop Service or PDB at a transaction boundary or leverage Continuous Application Availability to stop service at a request boundary.

    • Oracle Connection Manager in Traffic Director Mode leverages TAF Failover Restore to reconnect and restore simple states.

• Unplanned database outages:

  For both pooled and non-pooled (dedicated) modes, Oracle Connection Manager in Traffic Director Mode supports unplanned outage for read–mostly applications by leveraging TAF Failover Restore to restore simple session state or cursor state and replay SELECT statements and first DML statement.

10.2.1.3 Database Links

Oracle Connection Manager in Traffic Director Mode supports database links, which extends high availability and failover to databases.

Starting with Oracle Database 21c, Oracle Connection Manager in Traffic Director Mode (TDM) supports the following types of database links:

• Fixed User: The user connects to the remote database using the username and password specified during the creation of the database link.
• Connected User: The user connects to the remote database using the credentials of the user accessing the database link. These credentials can either be a username and password, or external, such as Kerberos ticket.

You can use database links with Traffic Director Mode in the following scenarios:

• Scenario 1:

  When a client connects directly to the database

  In this scenario, both fixed user and connected user database links work.

• Scenario 2:

  When a client connects to the database through the Traffic Director Mode

  In this scenario, only fixed user database link works. The connected user database link does not work as the session between TDM and the database is a proxy user session. Proxy user sessions are not allowed over a database link for security reasons.

  Note:

  For the database links to work with TDM, the TDM should not be running in Proxy Resident Connection Pool (PRCP) mode for the particular database service.

10.2.1.4 Per-Service and Per-PDB Connection Pools

Proxy Resident Connection Pooling (PRCP) provides connection pools on the Oracle Connection Manager in Traffic Director Mode (CMAN-TDM) server. You can configure CMAN-TDM to establish either per-service or per-PDB pooled connections.

Per-Service PRCP

In per-service PRCP, CMAN-TDM creates a single, dedicated pool for the requested database service based on the SERVICE_NAME parameter specified in the connect string. When a client application requests a new connection, CMAN-TDM establishes a pooled connection from this service pool. Every time the application requests a connection to this service, CMAN-TDM returns a matching connection from its service pool.

For example, for incoming connection requests with the specified service names as Service1_PDB1 and Service2_PDB1, CMAN-TDM creates PRCP_for_Service1_PDB1 to support the Service1_PDB1 connections and PRCP_for_Service2_PDB1 to support the Service2_PDB1 connections.

Per-PDB PRCP

Per-PDB PRCP works in the same manner as per-service PRCP. In this mode, when a client application requests a new connection, CMAN-TDM again establishes a pooled connection to the requested service based on the SERVICE_NAME parameter value specified in the connect string. However, instead of creating a dedicated pool for this service, it creates a multi-service PDB pool that supports connections across all services registered with that PDB. Any available Oracle Connection Manager Gateway (CMGW) can accept a connection request to a service or PDB, based on load balancing.

For example, for incoming connection requests to Service1_PDB1 and Service2_PDB1 (both running on PDB1), CMAN-TDM creates PRCP_for_PDB1 to support the Service1_PDB1 and Service2_PDB1 connections.

Per-PDB PRCP has the following advantages over per-service PRCP:

• Reduces the number of connection pools on CMGW by consolidating multiple service pools into a single PDB pool. This helps in optimizing the database performance.

• Dynamically determines and refreshes the maximum size of a PDB pool based on the TDM_PERPDB_PRCP_CONNFACTOR value and the OCPU count allocated to each PDB.

  The per-PDB PRCP configuration is especially useful in multitenant environments like Autonomous Databases, where PDB administrators can configure and monitor PRCP on the database side instead of having to access CMAN-TDM hosts for PRCP configuration.

Oracle does not recommend switching between the per-service and per-PDB modes. If you do so, then the changes are applied only to the gateways that start after the reconfiguration.

Pool Size Configuration Settings

• For per-service PRCP, CMAN administrators specify the <session_pool> MAX_SIZE value in the oraaccess.xml on the CMAN-TDM host during the initial PRCP configuration.

• In the per-PDB PRCP mode, pool sizing is more autonomous. CMAN administrators specify a connection factor in the cman.ora file using the TDM_PERPDB_PRCP_CONNFACTOR parameter.

  The per-PDB PRCP setting determines the maximum size of a per-PDB PRCP pool based on the TDM_PERPDB_PRCP_CONNFACTOR parameter value and the Oracle Compute Unit (OCPU) count allocated to each PDB automatically. A background process automatically fetches these values and resizes the pool. This derived maximum size value overrides the <session_pool> MAX_SIZE parameter configured in the oraaccess.xml file.

  You must set the sqlnet.ora parameter TCP.ALLOWED_PROXIES on the Oracle Database server to list the allowed CMAN instances that can fetch the OCPU count.

V$TDM_STATS View

In the per-PDB PRCP mode, PDB administrators can query the V$TDM_STATS view on the database to display usage statistics for CMAN-TDM. In this view, you can analyze an aggregated data for all inbound connections, such as the number of client requests that have retrieved a session in the pool, the number of active client connections, the number of busy and free server connections, the maximum number of connections reached, and so on. This view helps in the monitoring and tuning of CMAN-TDM.

A separate background thread fetches the statistical data from each CMGW and uploads to PDB at regular intervals. You can configure this time interval using the cman.ora parameter TDM_STATS_FREQUENCY.

10.2.1.5 Implicit Connection Pooling

Client applications that do not use an application connection pool can leverage connection pooling capabilities without making any application-level change or calling the pooling APIs.

Overview

Starting with Oracle Database 23ai, Proxy Resident Connection Pooling (PRCP) supports implicit connection pooling. This feature enables the automatic assignment of PRCP servers to and from an application connection at runtime when the application starts and finishes database operations, even if the application does not explicitly release the connection.

With implicit connection pooling, a database session from PRCP automatically gets mapped to and unmapped from an application connection without the explicit session pool API calls from the client. PRCP implicitly detects an end of request boundary (statelessness of the session) and releases the session back to the connection pool. For example, for a transaction, the application can implicitly use or reuse an available session from a pool of stateless sessions and then release the session back to the pool after the transaction is complete.

Implicit connection pooling helps in reducing the size of PRCP pools required. It provides better scalability and an efficient use of database resources for applications that do not use connection pools, such as Oracle Call Interface (OCI) Session Pool or Java Database Connectivity (JDBC) Oracle Universal Connection Pool (UCP).

Statement and Transaction Boundaries

Implicit connection pooling uses time boundaries to release a session back to the connection pool. A time boundary is a point in time in the life-cycle of the application when an application session is released back to the pool.

You can enable implicit connection pooling by setting the POOL_BOUNDARY parameter in the connect string, Easy Connect syntax, or tnsnames.ora file. Using this parameter, you specify one of these time boundaries:

• Statement Boundary: To release a session back to the PRCP pool when the session is implicitly stateless.

• Transaction Boundary: To release a session back to the PRCP pool when a transaction ends implicitly or explicitly, or when a transaction is not available and the session is stateless.

Note:

A session is implicitly stateless when all open cursors in a session have been fetched through to completion and there are no active transactions, temporary tables, or temporary LOBs. The release to the pool closes any active cursors, temporary tables, and temporary LOBs.

10.2.2 Configuring cman.ora File for Oracle Connection Manager in Traffic Director Mode

You can set up Oracle Connection Manager in Traffic Director Mode using the TDM=YES setting in the cman.ora file.

Sample cman.ora configuration for Oracle Connection Manager in Traffic Director Mode

CMAN_1=
	(CONFIGURATION=
		(ADDRESS_LIST=
		      (ADDRESS=(PROTOCOL=tcp)(HOST=TDMHOST)(PORT=1522))
		)
		(RULE_LIST=
		      (RULE=(SRC=*)(DST=*)(SRV=*)(ACT=accept))
		)
    	  	(PARAMETER_LIST=
		      (TDM=YES)
		      (TDM_THREADING_MODE=DEDICATED)
		      (MAX_GATEWAY_PROCESSES=8)
		      (MIN_GATEWAY_PROCESSSES=3)
		)
	 )
wallet_location =
	(SOURCE=
		(METHOD=File)
		(METHOD_DATA=
			(DIRECTORY=wallet_location)
		)
	)
SQLNET.WALLET_OVERRIDE = TRUE

Note:

The parameter WALLET_LOCATION is deprecated for use with Oracle Database 23ai for the Oracle Database server. It is not deprecated for use with the Oracle Database client.

For Oracle Database server, Oracle recommends that you use the WALLET_ROOT system parameter instead of using WALLET_LOCATION.

10.2.3 Configuring a Wallet for Oracle Connection Manager in Traffic Director Mode Proxy Authentication

Oracle Connection Manager in Traffic Director Mode connects to the databases using the wallet that must be configured with cman.ora file.

This wallet has the user name and the password information for the tdm user used by Oracle Connection Manager in Traffic Director Mode for proxy authentication. This tdm user must exist on all the databases that the Oracle Connection Manager in Traffic Director Mode connects to.

The following setting causes all outbound connections from Oracle Connection Manager in Traffic Director Mode to use the credentials in the wallet at the specified location for proxy authentication:

WALLET_LOCATION=
	(SOURCE=
		(METHOD=FILE)
		(METHOD_DATA=
			(DIRECTORY=wallet_location)
		)
 	)
SQLNET.WALLET_OVERRIDE=TRUE

Note:

The parameter WALLET_LOCATION is deprecated for use with Oracle Database 23ai for the Oracle Database server. It is not deprecated for use with the Oracle Database client.

For Oracle Database server, Oracle recommends that you use the WALLET_ROOT system parameter instead of using WALLET_LOCATION.

The wallet must be configured for each service. If a new service is added, then you must supply the credentials for the new service using the same wallet.

Note:

Whenever a new service is added and the credentials for the new service are added to the wallet, the Oracle Cloud Traffic Manager should be restarted for the changes to take effect.

• Enabling Oracle Connection Manager in Traffic Director Mode to Use External Password Store
  Steps involve creating an Oracle wallet and creating database connection credentials in that wallet for each database service.

10.2.3.1 Enabling Oracle Connection Manager in Traffic Director Mode to Use External Password Store

Steps involve creating an Oracle wallet and creating database connection credentials in that wallet for each database service.

Step 1: Create a wallet on Oracle Connection Manager in Traffic Director Mode by using the following syntax at the command line:

mkstore -wrl wallet_location -create

wallet_location is the path to the directory where you want to create and store the wallet.

This command creates an Oracle wallet with the auto-login feature enabled at the specified location:

orapki wallet create -wallet wallet_location -auto_login
Enter password: password
Enter password again: password

The auto-login feature enables Oracle Connection Manager in Traffic Director Mode to access the wallet contents without supplying a password.

Step 2: Create database connection credentials in the wallet by using the following syntax at the command line:

mkstore -wrl wallet_location -createCredential db_service_name username password

wallet_location is the path to the directory where you created the wallet in Step 1. The db_service_name is the service name used by the application in its connect string while connecting to Oracle Connection Manager. The username and password are the tdm user name and password.

Note:

The mkstore wallet management command line tool is deprecated with Oracle Database 23ai, and can be removed in a future release.

To manage wallets, Oracle recommends that you use the orapki command line tool.

Repeat this step for each database service that must be accessed by using Oracle Connection Manager in Traffic Director Mode.

For TCP/IP with TLS (TCPS) configuration, Oracle Connection Manager in Traffic Director Mode wallet is already created. In this case, you can skip Step 1 and specify wallet_location in mkstore as the same location used for TCPS configuration.

Note:

• The same tdm user can be used across all services for a given database. However, if required, a different tdm user can also be associated for each service.

• For pluggable database (PDB) services, there are two choices for setting up the tdm user:

  Common tdm user: tdm user can be a common user, in which case Oracle Connection Manager in Traffic Director Mode uses a single set of credentials for proxy authenticating users from different PDBs in a multitenant container database (CDB).

  Per PDB tdm user: tdm user can be a PDB–specific user, in which case Oracle Connection Manager in Traffic Director Mode uses PDB–specific proxy user for proxy authenticating users in a specific PDB.

10.2.4 Configuring Databases for Oracle Connection Manager in Traffic Director Mode Proxy Authentication

Every database to which an application connects through Oracle Connection Manager in Traffic Director Mode must have a user, for example, tdm. Oracle Connection Manager in Traffic Director Mode uses proxy authentication and connects to the database as the tdm user. All the users that must connect through Oracle Connection Manager in Traffic Director Mode must be granted CONNECT THROUGH tdm privilege as follows:

ALTER user SCOTT GRANT CONNECT THROUGH tdm

10.2.5 Configuring Service Registration with Oracle Connection Manager in Traffic Director Mode

See Configuring Service Registration for Use with Oracle Connection Manager.

10.2.6 Configuring Proxy Resident Connection Pooling in Oracle Connection Manager in Traffic Director Mode

Oracle Connection Manager in Traffic Director Mode (CMAN-TDM) supports Proxy Resident Connection Pooling (PRCP). You can configure PRCP either for each database service or for an entire PDB. By default, PRCP is configured in the per-service mode.

Optionally, you can enable implicit connection pooling with PRCP.

1. Configure either per-service or per-PDB PRCP.

   • Per-service PRCP:

     This is the default PRCP configuration. Specify the following <session_pool> parameters in the oraaccess.xml file (available in the TNS_ADMIN directory of the CMAN-TDM server). You can specify these parameters in the <default_parameters> section or in the <config_descriptions> section. When specified in the <default_parameters> section, the setting applies to all connection pools in the application.

     Parameter	Description
     <enable>	You must set <enable> to true to make the session pool configuration effective. This is a mandatory parameter, that means, if <session_pool> is configured, then <enable> must also be configured.
     <min_size>	Minimum number of connections in the pool. The default value is 0. CMAN-TDM is a heterogeneous pool scenario, so all other values are ignored.
     <max_size>	Maximum number of connections in the pool. The default value is 0. This is a mandatory parameter, that means, if <session_pool> is configured, then <max_size> must also be configured.
     <increment>	Amount of increase in the number of connections in the pool as the pool expands. The default value is 1.
     <inactivity_timeout>	Maximum time in seconds for which a connection stays idle in the pool, after which it is terminated. The default value is 0. It means that there is no limit.
     <max_use_session>	Maximum number of times a connection can be retrieved and released to the pool. The default value is 0. It means that there is no limit.
     <max_life_time_session>	Time, in seconds, a connection must stay after it has been created in the pool. The default value is 0. It means that there is no limit.

     The oraaccess.xml file allows you to configure a connection pool for each required connection service.

     The following example shows two groups of connection parameters associated with its respective config_alias, the sales_config and the hr_config, where each connection string that the application uses is mapped with its respective config_alias, thus providing two proxy resident connection pools.

     <oraaccess xmlns="http://xmlns.example.com/oci/oraaccess"
                 xmlns:oci="http://xmlns.example.com/oci/oraaccess"
                 schemaLocation="http://xmlns.example.com/oci/oraaccess
                 http://xmlns.example.com/oci/oraaccess.xsd">
       <default_parameters>
       </default_parameters>
         <!-- 
              Create configuration descriptions, which are  
              groups of connection parameters associated with
              a config_alias. 
         --> 
       <config_descriptions>
         <config_description>
           <config_alias> sales_config </config_alias> 
           <parameters>
              <session_pool>
                 <enable>true</enable>
                 <min_size> 10 </min_size>
                 <max_size> 100 </max_size>
                 <increment> 5 </increment>
              </session_pool>
           </parameters>
         </config_description>
         <config_description>
           <config_alias> hr_config </config_alias> 
           <parameters>
              <session_pool>
                <enable>true</enable>       
               <max_size> 10 </max_size>
              </session_pool>
           </parameters>
         </config_description>
       </config_descriptions>
       <!--   
              Now map the connection string used by the application 
              with a config_alias.  
       --> 
       <connection_configs>
         <connection_config>
           <connection_string>sales.us.example.com</connection_string> 
           <config_alias>sales_config</config_alias> 
         </connection_config>
         <connection_config>
           <connection_string>hr.us.example.com</connection_string> 
           <config_alias>hr_config</config_alias> 
         </connection_config>
       </connection_configs>
     </oraaccess>
     

   • Per-PDB PRCP:

     Instead of creating a single dedicated pool for each requested service, you can configure a multi-service PDB pool to support connections across all services registered with the PDB.

     Based on the specified connection factor and the Oracle Compute Unit (OCPU) count allocated to your PDB, PRCP dynamically computes the maximum pool size. This maximum size value overrides the MAX_SIZE value configured in the oraaccess.xml file.

     1. On the database server, set the sqlnet.ora parameter TCP.ALLOWED_PROXIES to specify one or more CMAN instances (IP addresses or host names) that you want to allow for fetching the OCPU count.

        For example:

        TCP.ALLOWED_PROXIES=(10.1.1.1/24,cmanhost1.example.com)

     2. On the CMAN-TDM host, set the cman.ora parameter TDM_PERPDB_PRCP_CONNFACTOR to the required connection factor value.

        Any value equal to or greater than 1 enables per-PDB PRCP.

        For example:

        TDM_PERPDB_PRCP_CONNFACTOR=10

        Note:

        Ensure that you set the connection factor value within the maximum connections limit defined by the cman.ora parameter MAX_CONNECTIONS.

     3. To monitor the behavior of these pools, you can query the dynamic database view V$TDM_STATS. To do so, first enable statistics upload by setting the cman.ora parameter TDM_STATS_FREQUENCY to the required time interval value.

        Any value equal to or greater than 1 (up to the defined maximum value) enables statistics upload.

        For example:

        TDM_STATS_FREQUENCY=300

        Based on the specified frequency, CMAN-TDM fetches the data from each CMAN-TDM gateway and uploads to PDB.

2. (Optional) To enable implicit connection pooling with either per-service or per-PDB PRCP, on the client side, set the POOL_BOUNDARY parameter in the tnsnames.ora file, Easy Connect syntax, or directly as part of the command-line connect string.

   Implicit connection pooling automatically performs session mapping or unmapping based on the session state. This can help maximize the pooled server usage and reduce the server resource usage.

   Specify one of these time boundaries to release the session back to the PRCP pool:

   • STATEMENT: To release the session when the session is implicitly stateless.

     For example:

     inst1=
         (DESCRIPTION=
             (ADDRESS=(PROTOCOL=tcp)(HOST=sales-server)(PORT=1521))
             (CONNECT_DATA=
                 (SERVICE_NAME=sales.us.example.com)
                 (SERVER=POOLED)
                 (POOL_BOUNDARY=STATEMENT))
         ) 

   • TRANSACTION: To release the session when a transaction ends implicitly or explicitly, or when a transaction is not available and the session is stateless.

     For example:

     inst1=
         (DESCRIPTION=
             (ADDRESS=(PROTOCOL=tcp)(HOST=sales-server)(PORT=1521))
             (CONNECT_DATA=
                 (SERVICE_NAME=sales.us.example.com)
                 (SERVER=POOLED)
                 (POOL_BOUNDARY=TRANSACTION))
         ) 

   The release to the pool closes any active cursors, temporary tables, and temporary LOBs.

   Note:

   You must set the POOL_BOUNDARY parameter along with the SERVER=POOLED setting. Otherwise, implicit connection pooling is disabled and the POOL_BOUNDARY directive is ignored.

10.2.7 Configuring Oracle Connection Manager in Traffic Director Mode for Unplanned Events

Oracle Connection Manager in Traffic Director Mode implicitly subscribes to Fast Application Notification (FAN) events. For this events must be enabled in oraaccess.xml.

Use DBMS_SERVICE or SRVCTL (for an Oracle RAC database) to specify COMMIT_OUTCOME for this specific service.

See Also:

• Oracle Database PL/SQL Packages and Types Reference for information about DBMS_SERVICE

• Oracle Clusterware Administration and Deployment Guide for information about SRVCTL

10.2.8 Configuring Oracle Connection Manager in Traffic Director Mode for Planned Down Events

Oracle Connection Manager in Traffic Director Mode implicitly subscribes to Fast Application Notification (FAN) events. For this events must be enabled in oraaccess.xml.

For planned down events, use DBMS_SERVICE or SRVCTL to configure the service and set failover_mode to select, commit_outcome to TRUE, and failover_restore to LEVEL1.

See Also:

• Oracle Database PL/SQL Packages and Types Reference for information about DBMS_SERVICE

• Oracle Clusterware Administration and Deployment Guide for information about SRVCTL

10.2.9 Configuring Oracle Connection Manager in Traffic Director Mode for Service Affinity

Configure Oracle Connection Manager in Traffic Director Mode to modify the default load distribution mechanism for routing incoming connection requests.

By default, Oracle Connection Manager in Traffic Director Mode uses service affinity to select a gateway for routing incoming connection requests. All new connection requests are routed to the gateways associated with database services.

Use the cman.ora parameter SERVICE_AFFINITY to modify the default behavior and set the parameter to ON or OFF.

When using Proxy Resident Connection Pooling (PRCP), Oracle recommends that you set the SERVICE_AFFINITY parameter to OFF for better performance and resource utilization of gateway processes.

10.2.10 Configuring Transport Layer Security on Oracle Connection Manager in Traffic Director Mode

Create a wallet on the Oracle Connection Manager in Traffic Director Mode server (CMAN-TDM), and then specify the TCP/IP with Transport Layer Security (TLS) listening endpoint and wallet location in the cman.ora file.

Note:

Starting with Oracle Database 23ai, the Oracle Wallet Manager (OWM) is desupported.

Oracle recommends using the orapki command line tool to replace OWM.

1. Confirm that a wallet has been created and that it has a certificate:
   1. Log in to the Oracle Connection Manager in Traffic Director Mode server where the wallet resides.
   2. Run the following command using the orapki command-line tool:

      orapki wallet display -wallet wallet_location

      Where, wallet_location is the path to the directory where the wallet is stored.

      If your wallet directory contains the cwallet.sso file (auto-login wallet) and it contains a user certificate, then this command displays a user certificate without asking for a password.

      Ensure that cwallet.sso contains a user certificate. If the wallet does not contain a user certificate, create a wallet that contains a user certificate, and then run the following command to create cwallet.sso in your wallet directory:

      orapki wallet create -wallet wallet_location -auto_login

2. In the cman.ora file, create a listening endpoint that uses TCP/IP with TLS (TCPS) and set the WALLET_LOCATION parameter to specify the wallet location on the CMAN-TDM side.

   For example, this is a sample cman.ora file configured with the TCPS protocol address and WALLET_LOCATION parameter settings:

   CMAN_1=
   	(CONFIGURATION=
       		(ADDRESS_LIST=
   		      (ADDRESS=(PROTOCOL=tcps)(HOST=proxysvr)(PORT=1522))
   		      (ADDRESS=(PROTOCOL=tcp)(HOST=proxysvr)(PORT=1523))
   		)
   		(RULE_LIST=
   		      (RULE=(SRC=*)(DST=*)(SRV=*)(ACT=accept))
   		)
       		(PARAMETER_LIST=
   		      (MAX_GATEWAY_PROCESSES=8)
   		      (MIN_GATEWAY_PROCESSSES=3)
       		)
   	 )
   WALLET_LOCATION= 
   	(SOURCE=
   		(METHOD=File)
   		(METHOD_DATA=
   			(DIRECTORY=wallet_location)
   	  	)
   	)
   SQLNET.WALLET_OVERRIDE = TRUE

   Note:

   The parameter WALLET_LOCATION is deprecated for use with Oracle Database 23ai for the Oracle Database server. It is not deprecated for use with the Oracle Database client.

   For Oracle Database server, Oracle recommends that you use the WALLET_ROOT system parameter instead of using WALLET_LOCATION.

10.2.11 Oracle Connection Manager in Traffic Director Mode Restrictions

These features are not supported with Oracle Connection Manager in Traffic Director Mode (CMAN-TDM) for all drivers.

• Java Database Connectivity (JDBC) objects for Transparent Application Continuity (TAC)

• Advanced Queuing (AQ)

• Database Links

• Database Startup or Database Shutdown calls

• Sharding (or Oracle Globally Distributed Database)

• SQL Translation

• Dual session proxy authentication

• OS authentication

• Authentication as SYSDBA, SYSOPER, and so on

• SSL external authentication (such as DN) without explicitly passing user name and password

• Object REF

• Session switching

• Session migration

• OCIObject* calls for navigational access

• OCIPickerImage* calls

• OCIAnyData* calls

• OCISubscription* calls: Client-side subscriptions for Application Continuity (AC), TAC, Runtime Load Balancing (RLB), and Fast Application Notification (FAN)

• OCILCR*, OCIXStream* calls

• OCIStmtExecute:

  • Server-side scrollable cursor support

  • Implicit Results

• Change Notification (CQN)

• Client Result Cache

• Database Resident Connection Pool (DRCP): Multi-property tag and PLSQL callback

• OCIConnectionPool

• Real Application Security (only in Java)

• Bulk Copy (ODP.Net only)

• Self-Tuning (ODP.Net only)

• MultiThreadedServer (MTS) distributed transactions (ODP.Net only)

• Oracle Advanced Security (ASO) encryption and supported algorithms (ASO only)

In addition, the following tasks are not supported:

• Using SID instead of SERVICE_NAME in application-provided connect strings

• Pipelining statement executions

• Altering table's metadata

  This is because statements are always cached by CMAN-TDM.

• Changing password with Proxy Resident Connection Pool (PRCP) connections

• Application Continuity with Implicit Connection Pooling

  When connected to a TAC or AC service using PRCP or DRCP with Implicit Connection Pooling enabled, CMAN-TDM internally disables support for Application Continuity.

10.3 Configuring Oracle Connection Manager in Tunneling Mode for Reverse Connection

Oracle Connection Manager in tunnelling mode establishes tunnel connections between server CMAN and client CMAN. Clients can make reverse connections over tunnels by connecting to server cman.

Complete the tasks in the following topics to configure Oracle Connection Manager in tunneling mode:

• Configure cman.ora for Oracle Connection Manager in Server Tunneling Mode
  Use the tunneling parameter to set up Oracle Connection Manager in server tunnelling mode.
• Configure cman.ora for Oracle Connection Manager in Client Tunnelling Mode
  You must set the tunnel_address parameter in the cman.ora file to set up Oracle Connection Manager in client tunnelling mode.
• Configure Clients to Make Reverse Connection
  When connecting to the server CMAN, the clients must specify client CMAN identifier.
• Configure Rules in Server CMAN for Tunnel Registration and Client Access
  The client CMAN connects to the server CMAN using tunnel service.
• Configure Oracle Database Server for Client Oracle Connection Manager
  You must register the database with client Oracle Connection Manager.

10.3.1 Configure cman.ora for Oracle Connection Manager in Server Tunneling Mode

Use the tunneling parameter to set up Oracle Connection Manager in server tunnelling mode.

Set the tunneling parameter to ON in the cman.ora file.

A sample cman.ora configuration for Oracle Connection Manager in server tunnelling mode.

CMAN_SERVER=
    (CONFIGURATION =
	(ADDRESS= (PROTOCOL=TCP)(HOST=SERVERCMAN)(PORT=1522))
       (RULE_LIST=
         (RULE=(SRC=*)(DST=*)(SRV=*)(ACT=accept))
       )
       (PARAMETER_LIST=
	  (TUNNELING=ON)
	  (GATEWAY_PROCESSES=16)
	  (NON_TUNNEL_GATEWAYS=8)
	  (TUNNEL_CAPACITY=32)
	  (TUNNEL_PROBE_INTERVAL=7)
       )
     )

10.3.2 Configure cman.ora for Oracle Connection Manager in Client Tunnelling Mode

You must set the tunnel_address parameter in the cman.ora file to set up Oracle Connection Manager in client tunnelling mode.

A sample cman.ora configuration for Oracle Connection Manager in client tunnelling mode.

CMAN_CLIENT=
 (CONFIGURATION=           
   (TUNNEL_ADDRESS=                       
     (DESCRIPTION=
       (ADDRESS=(PROTOCOL=TCP)(HOST=SERVERCMAN)(PORT=1522))                       
       (CONNECT_DATA=(TUNNEL_ID=south))
     )
    )
    (ADDRESS=(PROTOCOL=TCP)(HOST=CLIENTCMAN)(PORT=1523))            
    (RULE_LIST=                       
      (RULE=(SRC=*)(DST=*)(SRV=*)(ACT=accept))
     )
    (PARAMETER_LIST=                       
       (MAX_TUNNELS=2)                       
       (GATEWAY_PROCESSES=16)                       
       (NON_TUNNEL_GATEWAYS=8)
    )
  )

The default name for tunnel_id is RC.

10.3.3 Configure Clients to Make Reverse Connection

When connecting to the server CMAN, the clients must specify client CMAN identifier.

Use the TUNNEL_SERVICE_NAME parameter to specify the client CMAN identifier.

A sample tnsnames.ora configuration for client.

SOUTH_SALES_DB= 
	(DESCRIPTION=
	 (ADDRESS=(PROTOCOL=TCP)(HOST=SERVERCMAN)(PORT=1522))
	 (CONNECT_DATA =
	   (TUNNEL_SERVICE_NAME=south)
   	   (SERVICE_NAME=SALES)
	 )
	)

Note:

source_route is not supported for reverse connection.

10.3.4 Configure Rules in Server CMAN for Tunnel Registration and Client Access

The client CMAN connects to the server CMAN using tunnel service.

The tunnel ID of client CMAN is registered as a service in server CMAN.

• Configure Rules in Server CMAN using rule_list Syntax
  You must add a rule for each client CMAN as source, and service as tunnel. To allow client connections to a client CMAN, add a rule for service that identifies the client CMAN.
• Configure Rules in Server CMAN Using rule_group Syntax
  Add a group for each tunnel ID. The rule list in the group grants access to the required source addresses.

10.3.4.1 Configure Rules in Server CMAN using rule_list Syntax

You must add a rule for each client CMAN as source, and service as tunnel. To allow client connections to a client CMAN, add a rule for service that identifies the client CMAN.

You must set destination as * or localhost.

A sample cman.ora configuration for server Oracle Connection Manager in tunnelling mode using rule_list.

CMAN_SERVER=
   (CONFIGURATION=
     (ADDRESS=
        (PROTOCOL=TCP)(HOST=SERVERCMAN)(PORT=1522))            
        (RULE_LIST=                       
          (RULE=(SRC=CLIENTCMAN)(DST=*)(SRV=tunnel)(ACT=accept))                       
          (RULE=(SRC=CLIENTHOST)(DST=*)(SRV=south)(ACT=accept))
        )            
      (PARAMETER_LIST=                       
          (TUNNELING=ON)                       
          (GATEWAY_PROCESSES=16)                       
          (NON_TUNNEL_GATEWAYS=8)                       
          (TUNNEL_CAPACITY=32)                       
          (TUNNEL_PROBE_INTERVAL=7)
      )
   )

10.3.4.2 Configure Rules in Server CMAN Using rule_group Syntax

Add a group for each tunnel ID. The rule list in the group grants access to the required source addresses.

You must set destination as * or localhost.

A sample cman.ora configuration for server Oracle Connection Manager in tunnelling mode using rule_group.

CMAN_SERVER=
    (CONFIGURATION=
	(ADDRESS=(PROTOCOL=TCP)(HOST=SERVERCMAN)(PORT=1522))
       (RULE_GROUP=
         (GROUP=
           (DESCRIPTION=(NAME=south))
           (RULE_LIST=(RULE=(SRC=CLIENTCMAN)(DST=*)(SRV=*)(ACT=accept)))
	    (RULE_LIST=(RULE=(SRC=CLIENTHOST)(DST=*)(SRV=*)(ACT=accept)))
	  )
         (GROUP=
           (DESCRIPTION=(NAME=cmon))
           (RULE_LIST=(RULE=(SRC=*)(DST=*)(SRV=*)(ACT=accept)))
          )
       )
       (PARAMETER_LIST=
	    (TUNNELING=ON)
	    (GATEWAY_PROCESSES=16)
	    (NON_TUNNEL_GATEWAYS=8)
	    (TUNNEL_CAPACITY=32)
	    (TUNNEL_PROBE_INTERVAL=7)
        )
     )

10.3.5 Configure Oracle Database Server for Client Oracle Connection Manager

You must register the database with client Oracle Connection Manager.

Section Configuring the Oracle Database Server for Oracle Connection Manager of this guide explains how to register the database with Oracle Connection Manager.

Note:

Static routing is not supported by Oracle connection manager in tunnelling mode.

10.4 Using Oracle Connection Manager as a Bridge for IPv4 and IPv6

In some database connection environments, a client and database may use different versions of the IP protocol so that complete connectivity does not exist. In this case, at least two hops in the connection use different versions of the IP protocol.

For example, a request passes from an IPv4 source to an IPv6 destination, from an IPv6 source to an IPv4 destination, or from IPv6 to IPv6 through an IPv4 network.

You can use Oracle Connection Manager as a network bridge between IPv4 and IPv6. To serve as a bridge, Oracle Connection Manager must run on a dual-stack host configured with at least one IPv4 interface and at least one IPv6 interface.

Use the Oracle Connection Manager filtering feature to filter based on an IPv6 address. You can base rules on complete or partial IP addresses. The following figure shows the format of an IPv6 address:

Figure 10-1 IPv6 Address Format

Description of "Figure 10-1 IPv6 Address Format"

The numbers at the top of the diagram indicate the number of bits in the address. Each hexadecimal character in an IPv6 address represents 4 bits. Bits 4-16 are the Top-Level Aggregation Identifier (TLA ID) portion of the address. Bits 25-49 are the Next-Level Aggregation Identifiers (NLA ID).

For example, in the address 2001:0db8::203:BAFF:FE0F:C74B, the binary representation of the first four hexademical characters (2001) is as follows:

0010000000000001

Thus, the first 3 bits in the address are 001. The TLA ID portion of the address is 0000000000001.

The following procedure describes how to create a rules filter for IPv6 address:

1. Navigate to the cman.ora file located in the ORACLE_BASE_HOME/network/admin directory.

   If the cman.ora file is not present in the ORACLE_BASE_HOME/network/admin directory, then check for the file in the ORACLE_HOME/network/admin directory.

2. Open the cman.ora file with a text editor.
3. Create a RULE in the RULE_LIST based on IPv6 address format.

   For example, assume that the source host is an IPv6-only host with address 2001:0db8::203:BAFF:FE0F:C74B, whereas the destination is an IPv4-only host named SALESL1593. You configure Oracle Connection Manager as an IPv6-to-IPv4 bridge by creating one of the following rules:

   Type of Rule	Description	Example
   Filter based on subnet ID	Filtering is based on the 64 bits up to and including the subnet ID	(RULE = (SRC = 2001:0db8::203:BAFF:FE0F:C74B/64) (DST = SALESL1593) (SRV = SALES) (ACT = ACCEPT) (ACTION_LIST = (AUT=ON)(MOCT=10)(MIT=30)(CONN_STATE=YES)) )
   Filter based on NLA ID	Filtering is based on the 48 bits up to and including the NLA ID	(RULE = (SRC = 2001:0db8::203:BAFF:FE0F:C74B/48) (DST = SALESL1593) (SRV = SALES) (ACT = ACCEPT) (ACTION_LIST = (AUT=ON)(MOCT=10)(MIT=30)(CONN_STATE=YES)) )
   Filter based on TLA ID	Filtering is based on the 16 bits up to and including the TLA ID	(RULE = (SRC = 2001:0db8::203:BAFF:FE0F:C74B/16) (DST = SALESL1593) (SRV = SALES) (ACT = ACCEPT) (ACTION_LIST = (AUT=ON)(MOCT=10)(MIT=30)(CONN_STATE=YES)) )
   Filter based on number of bits	Filtering is based on the first 60 bits of the address	(RULE = (SRC = 2001:0db8::203:BAFF:FE0F:C74B/60) (DST = SALESL1593) (SRV = SALES) (ACT = ACCEPT) (ACTION_LIST = (AUT=ON)(MOCT=10)(MIT=30)(CONN_STATE=YES)) )

10.5 Using Oracle Connection Manager to Prevent Denial-of-Service Attacks

You can enforce a limit on the number of client connections that Oracle Connection Manager (CMAN) can handle from an IP address in a specific time interval.

Malicious clients can send excessive connection requests to the server node. This can saturate the capacity of CMAN to handle new connections per second, and thus cause denial-of-service (DoS) attacks on your database. Using the IP rate limit feature, you can limit the maximum number of new connections allowed from an IP address. This helps to prevent DoS attacks by detecting malicious clients early and rejecting those connections.

To enforce IP rate limit, set the IP_RATE_COUNT parameter in the cman.ora configuration file. This parameter specifies the number of connections that are allowed from a single IP address. The specified IP rate limit is enforced at the CMAN endpoint level.

If required, you can also set the following optional parameters in the cman.ora file:

• IP_RATE_INTERVAL: Specifies the time interval, in seconds, for which IP_RATE_COUNT connections are accepted from the IP address.

• IP_RATE_BLOCK: Specifies the duration, in minutes, for which the IP address is blocked after exceeding the specified IP rate limit.

If a connection exceeds the IP_RATE_COUNT per IP_RATE_INTERVAL limit, then CMAN rejects the IP address and blocks it for IP_RATE_BLOCK minutes. CMAN records an IP rate limit enforced for ip address error message in the Oracle Connection Manager log file.

10.6 Starting and Stopping Oracle Connection Manager

After configuring Oracle Connection Manager, you can start and administer it using the Oracle Connection Manager Control (CMCTL) utility.

At the operating system command line, the basic syntax for this utility is:

cmctl [command] [argument1 . . . argumentN] [-c instance_name]

The -c parameter specifies the Oracle Connection Manager instance that you want to administer. Instances are defined in the cman.ora file.

Note:

The use of password access to Oracle Connection Manager parameters is desupported in Oracle Database 23ai.

Oracle provides an enhanced connection method, Local Operating System Authentication" (LOSA), which permits only the user who started CMAN to perform admin operations. This method is consistent with other operating system authentication methods used with Oracle Database. If you are currently using password access to CMAN, then Oracle recommends that you remove the CMAN password, and instead rely on LOSA.

To start and stop Oracle Connection Manager using the Oracle Connection Manager Control utility:

1. Create the cman.ora file.
   A sample file is located in the ORACLE_BASE_HOME/network/admin/samples directory after installation of Oracle Connection Manager.
2. Start Oracle Connection Manager using one of the following methods:
   • At the command line:

     Run the STARTUP command. For example:

     cmctl STARTUP -c [cman_example_instance]

     The command starts the listener, Connection Manager Administration (CMADMIN), and gateway processes for an instance named cman_example_instance.

   • At the CMCTL prompt:

     At the command line, enter cmctl with no arguments to obtain the CMCTL prompt, and then run the ADMINISTER and STARTUP commands. For example:

     cmctl
     CMCTL> ADMINISTER [cman_example_instance]
     CMCTL> STARTUP
     

3. Stop a running instance of Oracle Connection Manager using one of the following methods:
   • At the command line:

     Run the SHUTDOWN command. For example:

     cmctl SHUTDOWN -c [cman_example_instance]

   • At the CMCTL prompt:

     At the command line, enter cmctl with no arguments to obtain the CMCTL prompt, and then run the ADMINISTER and SHUTDOWN commands. For example:

     cmctl
     CMCTL> ADMINISTER [cman_example_instance]
     CMCTL> SHUTDOWN
     

10.7 About CMCTL REST Interface

CMCTL REST interface helps you manage Oracle Connection Manager (Oracle CMAN) instance from remote machines using REST interface. A client that supports HTTPS can issue CMCTL equivalent commands. Each REST API call must have WWW-Authenticate HTTPS header with Basic authentication method.

• Configuring CMCTL REST Interface
  Use the cman.ora REST_ADDRESS parameter to configure REST endpoint hostname and port. The CMCTL REST interface authentication uses user name and password available in an Oracle CMAN wallet.
• REST APIs for CMCTL Commands
  Use CMCTL REST interface to automate CMAN tasks in cloud deployments. This functionality is similar to the CMAN cmctl control utility.

10.7.1 Configuring CMCTL REST Interface

Use the cman.ora REST_ADDRESS parameter to configure REST endpoint hostname and port. The CMCTL REST interface authentication uses user name and password available in an Oracle CMAN wallet.

1. Add the REST_ADDRESS attribute under the parameters section of the cman.ora file.
2. Create an Oracle wallet.
   An Oracle wallet is a file that stores certificates and authentication credentials. Use the orapki utility to create an Oracle wallet.
   You can import a certificate from a recognized authority into an Oracle Wallet or you can create your own authorized and signed certificate and use it with CMAN Oracle wallet. You can also use a self-signed Oracle wallet.
   For example, to create a wallet with a self-signed certificate, run the following commands:

   $ORACLE_HOME/bin/orapki  wallet create -wallet wallet directory
   $ORACLE_HOME/bin/orapki wallet add -wallet wallet directory -dn ‘cn=root_test, c=US’ -keysize 2048   -self_signed    -validity 365

   Where wallet directory is the file system directory location where the wallet is created.

   Note:

   Ensure that this directory is not readable by any group or other users.
3. Add CMAN REST client user name to the wallet.
   CMCTL REST interface process supports only HTTPS protocol. HTTP protocol is not supported. This wallet file must not have read permission to any group or other users. It should have read permissions only to the user owning the CMAN instance.
   Use the mkstore utility to store user name and password in an Oracle CMAN wallet.
   For example:

   mkstore -wrl wallet_directory -createEntry myusername my_password

   Note:

   The mkstore wallet management command line tool is deprecated with Oracle Database 23ai, and can be removed in a future release.

   To manage wallets, Oracle recommends that you use the orapki command line tool.

4. Create an auto-login wallet.
   Oracle CMAN requires auto-login wallet to start HTTPS endpoint. Run the following command to create an auto-login wallet:

   $ORACLE_HOME/bin/orapki wallet create -wallet wallet_location -auto_login

   where wallet_location is the directory where you have created the CMAN wallet.

   Note:

   Oracle has introduced a new auto-login wallet version (7) with Oracle Database 23ai. Version 6 of the Oracle local auto-login wallet is deprecated.

   You can update your local auto-login wallet by modifying it with orapki.

5. Specify the wallet location in the cman.ora file. Update the cman.ora file with wallet directory outside of cman alias:

   CMAN=
     (CONFIGURATION=
         .. .. 
       (RULE_LIST=
          . . . )
       (PARAMETER_LIST=
         
         . . . ))
   Wallet_location= … 

   For example:

   WALLET_LOCATION=
     (SOURCE=(METHOD=FILE) 
        (METHOD_DATA=
            (DIRECTORY=wallet directory))
      )

   Note:

   The parameter WALLET_LOCATION is deprecated for use with Oracle Database 23ai for the Oracle Database server. It is not deprecated for use with the Oracle Database client.

   For Oracle Database server, Oracle recommends that you use the WALLET_ROOT system parameter instead of using WALLET_LOCATION.

10.7.2 REST APIs for CMCTL Commands

Use CMCTL REST interface to automate CMAN tasks in cloud deployments. This functionality is similar to the CMAN cmctl control utility.

CMCTL REST interface uses local operating system authentication between REST interface process and Oracle CMAN listener.

After you start an Oracle CMAN instance with REST configuration, you can make a REST call with HTTPS basic authentication.

Use the curl command line tool to verify CMAN REST API. For example to list the services that are running, use the following command:

Note:

The curl command is used for testing and verification purposes only.

curl -X GET -u username:password https://cmanhostname:rest_port/show/services

10.8 Migrating CMAN Sessions During Patching

You can migrate the established client/server sessions from one Oracle Connection Manager (CMAN) instance to another Oracle CMAN instance during a planned upgrade or patching of Oracle CMAN with zero downtime.

You can migrate live sessions with data in-transit without disrupting the service. Any operations that are running either on a client or on a server continue to run seamlessly during the migration without loss of service. You can also add new client connections during the migration.

Perform the following steps to migrate client/server sessions:

You must have either upgraded Oracle CMAN to the latest release or applied the latest patch.

1. Install the upgraded Oracle CMAN or the patched Oracle CMAN in a new ORACLE_HOME.
2. Use the same cman.ora file that you used for configuring Oracle CMAN to configure the new Oracle CMAN instance.
3. Start the new Oracle CMAN instance from the new ORACLE_HOME in migration mode. Use the following command:

   cmctl startup –migrate -c cman_alias

   This command starts a new Oracle CMAN instance and initiates migrating of sessions from old Oracle CMAN instances. An old Oracle CMAN instance will exit as soon as the migration is complete or after 7 minutes timeout.

   The address of the old Oracle CMAN instance is added in the cman.ora file with the alias, cman_alias_old. You can use this alias to control and check the status of old Oracle CMAN instance during migration.

You can migrate sessions in the following scenarios:

• If both client to Oracle CMAN and Oracle CMAN to server use TCP.
• If either a client or a server uses TCPS (TLS) on one end and TCP on the other end. You must install Oracle Database 21c or later on both, the client using TCPS and the server using TCPS.

Unsupported connections remain connected till the timeout duration.

Note:

• Session migration is supported only for Oracle CMAN in regular mode and not for Oracle CMAN in Traffic Director Mode.
• If both client to Oracle CMAN and Oracle CMAN to server use TCPS, then migration is not supported.
• Currently, session migration is not supported on Microsoft Windows.

10.9 Oracle Connection Manager Enhancements

Oracle Connection Manager proxies and screens request for Oracle Database Server.

• Oracle Connection Manager provides a more secure access to the server by supporting the Transport Layer Security (TLS) protocol. With this support, the database client can communicate to the server through Oracle Connection Manager over TCPS protocol. You can also configure the Oracle Connection Manager to have TLS connection on one side and non-TLS connection on the other side. This also acts as a secure way to hide the internal database servers for the outside clients connecting from the internet.

  Multiplexing: If the gateway already has the TCPS connection to the endpoint requested by the database client, then it multiplexes the new connect request on the same connection.

• It can listen on multiple protocol addresses. With multiple listening endpoints, Oracle Connection Manager is now able to support both TCP and TCPS at the same time. The existing single protocol address configuration is still supported. For example:

  CMAN_ALIAS=
   (configuration=
   (address_list=
   (address=(protocol=TCP)(host=a.b.c.d)(port=12522))
   (address=(protocol=TCPS)(host=a.b.c.d)(port=12523))
  )
  ..
  )
  

• It has the addition of network data compression facility to improve network throughput and make data transfer faster between the Oracle Database Client and the Oracle Database Server. This is done in different ways according to the database client, database server, and the next hop compression ability. Compression is enabled between any two nodes if it is negotiated by them

  If more than two consecutive nodes support and negotiate compression, such case is handled in a way that the intermediate node just relays the compressed data to the next node without performing decompression.

  Compression is supported between the Oracle Connection Manager and the server, even if the Oracle Database Client is earlier than the Oracle Database 12c release and cannot support compression.

• It supports up to 2 MB SDU enabling the Oracle Database Client and the Oracle Database Server to negotiate higher SDU when establishing connection through Oracle Connection Manager.

• Starting with this release, valid node checking for registration is enabled by default in Oracle Connection Manager. By default, only the databases on local node are allowed to register with Oracle Connection Manager. The databases on remote node can be permitted or denied to register with Oracle Connection Manager through the use of parameters REGISTRATION_INVITED_NODES and REGISTRATION_EXCLUDED_NODES.

• Starting with Oracle Database 21c, you can manage distribution of bandwidth across services using Oracle Connection Manager.

  Oracle Connection Manager has the following enhancements:

  • REST APIs for CMCTL Commands
  • GROUP syntax for rules
  • BANDWIDTH in bytes per second at service level