10 Configuring Oracle Connection Manager

Oracle Connection Manager is a proxy server that forwards connection requests to databases or other proxy servers. It operates on the session level. It usually resides on a computer separate from the database server and client computers. Oracle Connection Manager is available for installation with Oracle Database 12c Enterprise Edition. It is a custom installation option on the Client disk.

The primary functions of Oracle Connection Manager are:

  • Access control: To use rule-based configuration to filter user-specified client requests and accept others.

  • Session multiplexing: To funnel multiple client sessions through a network connection to a shared server destination.

This chapter describes how to configure Oracle Connection Manager features. This chapter contains the following topics:

See Also:

About the cman.ora File

You configure the computer that hosts Oracle Connection Manager by setting parameters in the cman.ora file. The cman.ora file resides on the computer that hosts Oracle Connection Manager, and is located in the 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, /27 represents a subnet mask that comprises 27 left-most bits. Only the first 27 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

Configuring Oracle Connection Manager

In order to configure Oracle Connection Manager you must configure the proxy server, database, and clients. The following tasks describe the general procedure:

Task 1   Configure the cman.ora file on the Oracle Connection Manager computer.

The cman.ora file specifies the listening endpoint for the server, access control rules, and Oracle Connection Manager performance parameters.

"Configuring the cman.ora file for the Oracle Connection Manager Host" explains how to perform this task.

Task 2   Configure the clients with the protocol address of the Oracle Connection Manager listener.

"Configuring Clients for Oracle Connection Manager" explains how to perform this task.

Task 3   Configure the database server for session multiplexing. This task is optional.

"Configuring the Oracle Database Server for Oracle Connection Manager" explains how to perform this task.

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_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). The protocol TCPS is not 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.

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, "Rule-Level Parameters in cman.ora File"

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.

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.

This section contains the following topics:

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 listeners_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. 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"

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:

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. Figure 10-1 shows the format of an IPv6 address.

Figure 10-1 IPv6 Address Format

Description of Figure 10-1 follows
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_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))
)

See Also:

Using the Oracle Connection Manager Control Utility to Administer Oracle Connection Manager

The Oracle Connection Manager Control utility enables you to administer Oracle Connection Manager. When you issue commands from the operating system, the basic syntax for this utility is as follows:

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

In the preceding command, -c specifies the Oracle Connection Manager instance. You are prompted for the password if one has been set.

Caution:

There is an option to specify the password on the command line. However, this exposes the password on the screen, and is a potential security risk. Oracle recommends not using the password option (-p) on the command line.

For example, the following command starts the listener, Connection Manager Administration (CMADMIN), and gateway processes for an instance named cman1:

cmctl STARTUP -c cman1

You can also issue Oracle Connection Manager utility commands at the CMCTL prompt. To obtain the prompt, enter cmctl with no arguments at the operating system command line. The utility may prompt for a password if Oracle Connection Manager was installed with secure installation option. When you run CMCTL, the utility is started, and you can enter the necessary commands from the CMCTL prompt. The following is an example of the CMCTL prompt:

cmctl
CMCTL> STARTUP

Notes:

Before issuing the STARTUP command, do the following:

  • Create the cman.ora file. A sample file is located in the ORACLE_HOME/network/admin/samples directory after installation of Oracle Connection Manager.

  • Run the ADMINISTER command to choose an instance to start.

See Also: