SQL Server Magazine

Proxy servers provide security and performance benefits for your network. Netscape Proxy Server 3.5 turns your Windows NT server into a proxy server.

In this article, I first explain how to install Netscape Proxy Server. Then, I discuss how to configure proxy arrays and how you can use Netscape Proxy Server to provide reverse proxy services (and thus permit controlled external access to an internal Web site) and improve performance in a large organization that has multiple interconnected proxy servers.

Installation
You can install Netscape Proxy Server on an NT Server 4.0 or NT Workstation 4.0 system. The fast and simple installation process installs Netscape Administration Server, which you use to manage the proxy server and other Netscape servers on the system (e.g., the Enterprise Server computer, the Directory Server computer).

Netscape Proxy Server requires Netscape Navigator 4.0, which the installation CD-ROM includes. You use Navigator to access the Netscape Administration Server, which presents Netscape Proxy Server's Web interface. You can then restrict management access and use secure connections between Navigator and the proxy server. After you install Netscape Proxy Server's services, you must use Navigator to change Netscape Proxy Server's initial configuration.

If you install Netscape Proxy Server on a standalone server, the software requires minimal configuration. Typical configuration (e.g., for small sites where the server acts as a firewall between local Web browsers and the Internet) consists of dial-up access support and local cache support. You can usually set up a Netscape Proxy Server site in less than an hour. More complex configurations take more time, depending on the number of servers, the types of connections, and additional customization (e.g., mapping one URL to another).

Proxy Arrays
A proxy array is a group of proxy servers that share information. Proxy arrays let Web browsers access information through several routes depending on the information's location and how you connect the proxy servers.

A proxy server can obtain information directly from a Web site or indirectly through other proxy servers (standalone proxy servers or servers in an array). Figure 1 shows proxy servers accessing proxy arrays and other proxy servers. This configuration is appropriate if your connection speeds vary. For example, a corporate site might have a proxy array connected to a proxy server at a branch office via a low-speed ISDN connection. The branch office proxy server provides branch office users with cached access to the corporate site and the Internet via the corporate site.

A Netscape Proxy Server computer can forward information that a Web browser requests and that the computer obtains from a Web site directly to the Web browser. Alternatively, one or more Netscape Proxy Server computers can cache the information before forwarding it to the Web browser. The computer then uses the cache for subsequent requests for the information. Netscape Proxy Server supports the Internet Control Protocol. ICP lets adjacent proxy servers exchange information about cached data.

You configure proxy arrays after you install Netscape Proxy Server. You can set up links between proxy servers at any time, but for security reasons, you need to configure each array member at the member's computer. You must designate one of the members as the master proxy server; the master server is typically the first one you configure. The result of your configuration might be an array with local Web browsers accessing any of the proxy servers in the array. Netscape Proxy Server uses the Cache Array Routing Protocol (CARP) to link the proxy array.

You can configure arrays by using a text editor to modify configuration text files or through the Web interface that Screen 1 shows. The first method requires stopping and restarting the proxy server so that changes take effect. Configuration changes that you make via the Web interface can take effect immediately, or you can choose to have them take effect when the service restarts.

The Member List in Screen 1 shows part of the sibling list in a proxy array. You must add new members to the list at the member's site; the list doesn't include the server you're managing. You configure each member connection from the Member Configuration screen, taking security and bandwidth into account. Netscape Proxy Server supports SOCKS 5.0 for secure connections between servers. A secure configuration is useful when proxy servers at remote sites connect via the Internet or other unsecured communication links.

To set up proxy siblings or ICP neighbors, you must know the proxy server's name or IP address and port number. The array continues to operate even if one of the servers fails or you take a server offline.

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