4 Protocol Address Configuration

A network object is identified by a protocol address. When a connection is made, the client and the receiver of the request (listener or Oracle Connection Manager) are configured with identical protocol addresses.

The client uses this address to send the connection request to a particular network object location, and the recipient "listens" for requests on this address, and grants a connection based on its address information matching the client information.

This chapter contains these topics:

ADDRESSes and ADDRESS_LISTs
Protocol Parameters
Recommended Port Numbers
Port Number Limitations

ADDRESSes and ADDRESS_LISTs

Protocol address are comprised of ADDRESS and ADDRESS_LIST elements.

ADDRESS

Purpose

The ADDRESS parameter defines a protocol address.

Embed this parameter under an ADDRESS_LIST or DESCRIPTION parameter. A DESCRIPTION is used in a tnsnames.ora or a listener.ora file.

ADDRESS_LIST

Purpose

The ADDRESS_LIST parameter defines a list of protocol addresses that share common characteristics.

Example

(ADDRESS_LIST=
  (LOAD_BALANCE=on)
  (ADDRESS=
   (PROTOCOL=tcp)
   (HOST=sales-server)
   (PORT=1521))
  (ADDRESS=
   (PROTOCOL=tcp)
   (HOST=hr-server)
   (PORT=1521)))
 (ADDRESS_LIST=
  (ADDRESS=
   (PROTOCOL=tcp)
   (HOST=finance-server)
   (PORT=1521)))

Protocol Parameters

The listener and Oracle Connection Manager are identified by protocol addresses. Table 4-1, "Protocol-Specific Parameters" describes the parameters used by the Oracle protocol support.

Table 4-1 Protocol-Specific Parameters

Protocol	Parameter	Description
I PC	`PROTOCOL`	Specify `ipc` as the value.
	`KEY`	Specify a unique name for the service. Oracle Corporation recommends using the service name or the Oracle System Identifier (SID) of the service. Example: (PROTOCOL=ipc)(KEY=sales)
N amed Pipes	`PROTOCOL`	Specify `nmp` as the value.
	`SERVER`	Specify the name of the Oracle server computer.
	`PIPE`	Specify the pipe name you used to connect to the database server (the same `PIPE` keyword you specified on server with Named Pipes). This name can be any arbitrary name. Example: (PROTOCOL=nmp)(SERVER=sales)(PIPE=dbpipe0)
SDP	`PROTOCOL`	Specify `sdp` as the value.
	`HOST`	Specify the host name or IP address of the computer.
	`PORT`	Specify the listening port number. Example: (PROTOCOL=sdp)(HOST=sales-server)(PORT=1521) (PROTOCOL=sdp)(HOST=44.25.186.204)(PORT=1521) See Also: "Recommended Port Numbers"
T CP/IP	`PROTOCOL`	Specify `tcp` as the value.
	`HOST`	Specify the host name or IP address of the computer.
	`PORT`	Specify the listening port number. Example: (PROTOCOL=tcp)(HOST=sales-server)(PORT=1521) (PROTOCOL=tcp)(HOST=44.25.186.204)(PORT=1521) See Also: "Recommended Port Numbers"
T CP/IP with SSL	`PROTOCOL`	Specify `tcps` as the value.
	`HOST`	Specify the host name or IP address of the computer.
	`PORT`	Specify the listening port number. Example: (PROTOCOL=tcps)(HOST=sales-server)(PORT=2484) (PROTOCOL=tcps)(HOST=44.25.186.204)(PORT=2484) See Also: "Recommended Port Numbers"

Recommended Port Numbers

Table 4-2, "Recommended Port Numbers" lists the recommends the port numbers.

Table 4-2 Recommended Port Numbers

Port	Description
1521	Default listening port for client connections to the listener. In future releases, this port number may change to the officially registered port number of 2483 for TCP/IP and 2484 for TCP/IP with SSL.
1521	Default and officially registered listening port for client connections to Oracle Connection Manager
1830	Default and officially registered listening port for administrative commands to Oracle Connection Manager

Port Number Limitations

Oracle Corporation allows port numbers from 1 to 65535. Port numbers less than 1024 are reserved for use by privileged processes on many operating systems.

On certain operating systems, only privileged processes can listen for TCP connections on ports less than 1024. If you need to configure listener to listen on a port number less than 1024, follow these general steps. Your operating system may require different procedures.

Use Oracle Net Configuration Assistant or Oracle Net Manager to configure the listener with protocol addresses and other configuration parameters.

See Also:
Oracle Database Net Services Administrator's Guide
Log in as super user (root) and set file ownership and access permissions for the listener executable (tnslsnr) and the dependent shared libraries so that these files can be modified only by the super user.

Ensure that the permissions of the individual directories found in the path names to these files, starting with the root directory, are also modified in the same way.

Start the listener as root.

At the operating system prompt, enter tnslsnr with optional command line arguments. The usage is as follows:

tnslsnr [listener_name] [-user user] [-group group]

where:

Table 4-3 tnslsnr Utility Options

Option	Description
`listener_name`	Specify the name of the listener. If omitted, the default name `LISTENER` will be used.
`-user` `user`	Specify the user whose privileges the listener will use when super user (`root`) privileges are not needed. After performing the privileged operations, the listener will give up `root` privileges irreversibly.
`-group` `group`	Specify the group whose privileges the listener will use when super user (`root`) group privileges are not needed. After performing the privileged operations, the listener will give up `root` group privileges irreversibly.

The listener will temporarily switch to the provided user and group immediately after startup. All subsequent operations will be done with the specified user and group privileges, except the system calls necessary to listen on configured endpoints. The listener will revert to super user (root) for a short period of time to listen on reserved addresses, such as TCP ports less than 1024. After the listener starts listening on all of its endpoints configured in listener.ora, it will switch to the specified user and group irreversibly. Therefore, the listener will give up the root privilege that it initially had. In the current release, -user and -group command line arguments only accept user and group identifiers specified in numeric form.

For example, to execute a root listener called mylsnr and have it use privileges of a user identified as 37555 with a group identifier of 16, enter the following at the operating system command prompt. Note that 37555 could be the identifier for user oracle and 16 could be the identifier for the dba group.

tnslsnr mylsnr -user 37555 -group 16

After the listener has been started, you can administer it with the Listener Control utility.
Important Notes:
- Oracle Corporation recommends that the user under which the listener process runs be oracle, as described in the example in Step 3, or whichever user the listener process normally runs as on the operating system.
- Do not leave the listener process running as root because doing so is a security vulnerability.