5 Managing the Network Connections

5.1 Specifying Listener Ports and Addresses

The port that Oracle HTTP Server listens on when it is started depends on your installation type.

Table 5-1 contains information about Oracle HTTP Server ports.

If ports 7777 or 80, for example, are occupied, Oracle HTTP Server listens on the next available port numbers between a range of 7777-7877. Accordingly, it would listen on port 7778, and so on.

A file named setupinfo.txt is automatically generated in ORACLE_HOME/install on UNIX or ORACLE_HOME\install on Windows.It contains port information for Oracle HTTP Server. This file is generated at install time, and is not updated thereafter. If you restart Oracle HTTP Server, the information in this file becomes inaccurate.

You can change the Oracle HTTP Server listener port (SSL and non-SSL) after installation. If you make a port change, then you have to also update other components to use the new port number.

You can specify that the server listens on more than one port, selected addresses, or a combination. The Listen directive, located in the "Global Environment" of the httpd.conf file, specifies listener ports and addresses. Multiple Listen directives can be used to listen on multiple ports.

For example:

• Listen 7778

• Listen 12.34.56.78:80

  
  

  See Also: "Listen directive" in the Apache Server documentation.

  
  

5.2 Managing Interaction Between Server and Network

The following directives are used to specify how the server interacts with the network. They are located in the "Global Environment" of the httpd.conf file.

• ListenBackLog

• SendBufferSize

• TimeOut

  
  

  See Also: "httpd.conf File Structure"

  
  

5.3 Managing Connection Persistence

The following directives determine how the server handles persistent connections. They are located in the "Global Environment" of the httpd.conf file.

• KeepAlive

• KeepAliveTimeout

• MaxKeepAliveRequests

  
  

  See Also: Oracle Application Server Performance Guide "httpd.conf File Structure"

  
  

5.4 Obtaining Client IP Address

UseWebCacheIp is a global directive that enables Oracle HTTP Server to obtain IP address of a client. It can be set to "On" or "Off", and defaults to "Off". It is not set to "On" by default because it can open a security hole in some circumstances.

When OracleAS Web Cache acts as a reverse proxy in front of Oracle HTTP Server, the TCP connection from the client is terminated at OracleAS Web Cache. The TCP connection that Oracle HTTP Server sees actually originates at OracleAS Web Cache. Oracle HTTP Server gets the IP address of the client and uses it for various purposes, such as:

• Populating the REMOTE_ADDR CGI variable that can be used by applications in and behind Oracle HTTP Server to identify where the client came from.

• Evaluating mod_access allow/deny rules that allow the administrator to restrict access based on IP address.

Without the UseWebCacheIp directive, this functionality fails when OracleAS Web Cache is used in front of Oracle HTTP Server. This is because Oracle HTTP Server sees all connections coming from the same place, the IP address where OracleAS Web Cache is running.

With every request that OracleAS Web Cache forwards to Oracle HTTP Server, it sends a header that contains the IP address of the client connection that it received. If UseWebCacheIp is set to "On", then it directs Oracle HTTP Server to use the IP value from this header, instead of the value from the TCP connection as the client's IP address. This enables REMOTE_ADDR CGI variable to have the correct value, and allows mod_access to function correctly.

You should set this directive only if you are sure that the clients can only connect to Oracle HTTP Server through OracleAS Web Cache. If clients can connect directly to Oracle HTTP Server, then they have to find out the header that is used to transfer the client IP, and set it so that it would seem to have come from any IP address you want. In a typical set up, with a firewall and OracleAS Web Cache, the only port open through the firewall is the OracleAS Web Cache port. Hence, the only path from the client to Oracle HTTP Server goes through OracleAS Web Cache. In this case, it is safe to turn on UseWebCacheIp.

5.5 Configuring Reverse Proxies and Load Balancers

By default, Oracle Application Server installs using the local hostname as set up by ServerName directive in Oracle HTTP Server. Most Web sites tend to have a specific hostname or domain name for their Web or application server. However, this is not possible out of the box because with the ServerName directive, Oracle HTTP Server is instantiated with the local host.

Port 80 
Listen 7777 
Listen 80 
# Virtual Hosts 
# This section is mandatory for URLs that are generated by 
# the PL/SQL packages of the Oracle Portal and various other components 
# These entries dictate that the server should listen on port 
# 7777, but will assert that it is using port 80, so that 
# self-referential URLs generated specify www.oracle.com:80 
# This will create URLs that are valid for the browser since 
# the browser does not directly see the host server.oracle.com. 
NameVirtualHost 123.456.7.9:7777 
<VirtualHost server.oracle.com:7777> 
ServerName www.oracle.com 
Port 80 
</VirtualHost> 
# Since the previous virtual host entry will cause all links 
# generated by the Oracle Portal to use port 80, the server.company.com 
# server needs to listen on 80 as well since the Parallel Page 
# Engine will make connection requests to Port 80 to request the 
# portlets. 
NameVirtualHost 123.456.7.9:80 
<VirtualHost server.oracle.com:80> 
ServerName www.oracle.com 
Port 80 
<VirtualHost>