Reverse Proxy Administration of the WebSphere Caching Proxy

Abstract

This technote describes how to gain access to the Caching Proxy administration GUI when the proxy server is configured as a reverse proxy server.

Contents

Introduction

This technote describes how to gain access to the Caching Proxy administration GUI when the proxy server is configured as a reverse proxy server.

The Caching Proxy component of WebSphere Application Server Edge Components V6 is both a caching proxy server and a content filter. It can be used to provide a robust, efficient proxy server with an optional cache. The caching proxy server can be configured to operate as:

  • A forward proxy server for clients
  • A transparent proxy server for clients
  • A reverse proxy server for other back-end servers

The Caching Proxy is supported on AIX, HP-UX, Linux (Intel, z/390 zSeries, iSeries, or pSeries), Solaris, Windows 2000 Server, and Windows 2003 Server. For the purposes of this technote, the Caching Proxy is installed on a Windows 2000 Server system.

The Caching Proxy, when configured as a reverse proxy server, acts on behalf of one or many back-end servers. A reverse caching proxy intercepts client requests arriving from the Internet, forwards them to the appropriate back-end server content hosts, caches the returned data (if requested to), and delivers that data to clients across the Internet. The cached data can satisfy a request for the same pages at a later time. In this manner, a reverse proxy can reduce the amount of traffic and processing that a back-end server must perform to satisfy duplicate Internet requests for data, while at the same time improving the response time for those requests.

The Caching Proxy is administered using the browser-based Configuration and Administration forms GUI supplied with the Caching Proxy. These forms run CGI programs that edit the proxy server configuration file, ibmproxy.conf.

Default Caching Proxy installation

The Caching Proxy defaults to a forward proxy configuration when it is first installed. This default configuration includes a PASS directive in the ibmproxy.conf file that enables access to the Configuration and Administration forms. When a client browser requests the default home page from the caching proxy server, Frntpage.html is served. This page contains a hypertext link to the Configuration and Administration forms start page. For example, if the Caching Proxy server software is installed on a server named isicserver, when a client browser goes to the URL http://isicserver, the following page will be displayed.

Caching Proxy Frontpage.html

The following code example is a partial display of the ibmproxy.conf file as it exists after the Caching Proxy is first installed as a forward proxy. The highlighted PASS directive in the default ibmproxy.conf file enables access to Configuration and Administration forms.



.
.
Pass /wsApplet/* d:\IBM\edge\cp\server_root\admin-bin\webexec\*
Pass /errorpages/* d:\IBM\edge\cp\server_root\pub\en_US\errorpages\*
Pass /pac/* d:\IBM\edge\cp\etc
Pass /pacfiles/* d:\IBM\edge\cp\etc
#
# URL translation rules; If your documents are under
#
# NOTE: The installation defaults should be added below
# *** START NEW MAPPING RULES SECTION ***

# *** END NEW MAPPING RULES SECTION ***
Pass /* d:\IBM\edge\cp\server_root\pub\en_US\*
.
.



Configuring a reverse proxy

The Caching Proxy also includes a Configuration Wizard that enables you to configure an installed Caching Proxy to function as a reverse proxy (also referred to as a surrogate). To start the Configuration Wizard on a Windows system, click Start -> Programs -> IBM WebSphere -> Edge Components -> Caching Proxy -> Configuration Wizard. The Configuration Wizard allows you to:
  • Select the network port on which the proxy server will listen for HTTP requests.
  • Define the name of the back-end target content server.
  • Enter a user ID and password for the Caching Proxy server administrator.

The Configuration Wizard modifies only the essential directives in the ibmproxy.conf file that are required for a reverse proxy configuration. The following example is a partial display of the ibmproxy.conf file as it exists after the Configuration Wizard has been invoked to configure a reverse proxy. The highlighted PROXY directive in the modified ibmproxy.conf file enables the Caching Proxy to proxy client requests for a back-end server named RS600010 in domain ITSO.RAL.IBM.COM.



.
.
Pass /wsApplet/* d:\IBM\edge\cp\server_root\admin-bin\webexec\*
Pass /errorpages/* d:\IBM\edge\cp\server_root\pub\en_US\errorpages\*
Pass /pac/* d:\IBM\edge\cp\etc
Pass /pacfiles/* d:\IBM\edge\cp\etc
#
# URL translation rules; If your documents are under
#
# NOTE: The installation defaults should be added below
# *** START NEW MAPPING RULES SECTION ***

Proxy /* http://rs600010.itso.ral.ibm.com/* :80

# *** END NEW MAPPING RULES SECTION ***
Pass /* d:\IBM\edge\cp\server_root\pub\en_US\*
.
.



The PROXY directive added by the Configuration Wizard directs all client requests (those that have filtered through the previous PASS directives) to the back-end server named RS600010.ITSO.RAL.IBM.COM. In the following figure, the proxy server tried to redirect a client request to the RS600010 back-end server. The redirect was unsuccessful because that back-end server was unavailable.

Caching Proxy redirect to back-end server

Note that in the previous coding example the PROXY statement was added in the ibmproxy.conf file before the PASS statement that permits access to Configuration and Administrative forms. This placement of the PROXY directive disables browser access to Configuration and Administrative forms to manage the reverse proxy server.

To regain browser access to the Configuration and Administrative forms GUI, add the highlighted PASS directive to the ibmproxy.conf file, as shown in the following example.



.
.
Pass /wsApplet/* d:\IBM\edge\cp\server_root\admin-bin\webexec\*
Pass /errorpages/* d:\IBM\edge\cp\server_root\pub\en_US\errorpages\*
Pass /pac/* d:\IBM\edge\cp\etc
Pass /pacfiles/* d:\IBM\edge\cp\etc
#
# URL translation rules; If your documents are under
#
# NOTE: The installation defaults should be added below
# *** START NEW MAPPING RULES SECTION ***

Pass /pub/* d:\IBM\edge\cp\server_root\pub\en_US\*
Proxy /* http://rs600010.itso.ral.ibm.com/* :80

# *** END NEW MAPPING RULES SECTION ***
Pass /* d:\IBM\edge\cp\server_root\pub\en_US\*
.
.


Addition of this PASS directive re-enables access to Configuration and Administrative forms on the proxy server machine from a client browser. After this PASS directive has been added and the Caching Proxy restarted, type the following URL into a client browser to display the initial Configuration and Administrative form page: http://isicserver/pub/. Note that the ending forward slash (/) is required.

Caching Proxy Frntpage.html

Special Notices

This material has not been submitted to any formal IBM test and is published AS IS. It has not been the subject of rigorous review. IBM assumes no responsibility for its accuracy or completeness. The use of this information or the implementation of any of these techniques is a client responsibility and depends upon the client's ability to evaluate and integrate them into the client's operational environment.

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Publish Date
02 March 2005


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TIPS0536