Enabling Web Proxies

Primarily, Web proxies are enabled to improve the performance of requests made to external Web sites by Web users on your local network. Many of your users visit the same Web sites throughout the day. A Web proxy caches this external Web site content; Web browsers on your local network then read the cached content rather than use your potentially slower Internet connection. Recently, though, Web proxies have fallen out of favor as high-speed Internet connections have become commonplace.

To enable a Web proxy:

1.	Launch the Server Admin tool located in /Applications/Server, and authenticate as the administrator (Figure 9.75). Figure 9.75. Launch the Server Admin tool, and authenticate.
2.	Select the Web service for your server in the Computers & Services list (Figure 9.76). Figure 9.76. The Web service is selected in the Computers & Services list.
3.	Click the Settings button and then the Proxy tab . The Proxy pane displays your Web server's proxy settings (Figure 9.77). Figure 9.77. The Proxy pane lets you edit the Web server's proxy settings.
4.	Click the Enable Proxy check box.
5.	In the "Maximum cache size" field, set the maximum amount of space your Web server will use on the local hard drive for proxy cache files (Figure 9.78). Figure 9.78. Edit the "Maximum cache size" field.
6.	The default Web proxy cache folder is /var/run/proxy. To specify a different cache folder on the server's local drive, do either of the following: Enter the absolute path in the "Cache folder" field. Click the ellipsis button to use the browse dialog (Figure 9.79). Figure 9.79. Select the appropriate file on your server using the browse dialog.
7.	When you've finished making changes, click the Save button .

Tips

• When the cache reaches the maximum size, the oldest files are deleted from the cache folder.

• It's important to remember that proxy settings won't affect any of your Web site settings.

• In order for your clients to use the Web proxy, you must configure them to use it. Client computers aren't configured to use a Web proxy by default.

• If you have a slower Web server and a fast Internet connection, you may be better off without the Web proxy.

• The Server Admin tool should automatically restart the Web service when you click the Save button .

Configuring a Web Proxy on Clients

Configuring Web proxy usage on Mac OS X Client involves these steps:

1.	Open the Network System Preferences pane by opening System Preferences under the Apple menu and selecting the appropriate network location and port configuration (Figure 9.80). Figure 9.80. Configure a computer's network settings using the Network Preferences pane.
2.	Click the Proxies tab (Figure 9.81). Figure 9.81. Click the Proxies tab.
3.	Select the Web Proxy check box in the proxy list, and then enter the address to your proxy in the Web Proxy Server field (Figure 9.82). Figure 9.82. Enable and configure the Web proxy settings.
4.	When you've finished making changes, click the Apply Now button , and close the System Preferences application.

Configuring blocked Web sites

When you're using a Web proxy, all the Web traffic from your client computers must pass through the proxy server. You can take further advantage of this situation by creating a list of blocked Web site hosts. Doing so prevents your users from going to any Web site that you've defined in the list.

To block Web sites:

1.	Launch the Server Admin tool located in /Applications/Server, and authenticate as the administrator (Figure 9.83). Figure 9.83. Launch the Server Admin tool, and authenticate.
2.	Select the Web service for your server in the Computers & Services list (Figure 9.84). Figure 9.84. The Web service is selected in the Computers & Services list.
3.	Click the Settings button and then the Proxy tab . The Proxy pane displays your Web server's proxy settings (Figure 9.85). Figure 9.85. The Proxy pane lets you edit the Web server's proxy settings.
4.	If it isn't already selected, select the Enable Proxy check box.
5.	To add host names to the "Blocked hosts" list, do either of the following: Click the Add button , and enter the fully qualified host name (Figure 9.86). When you've finished entering the host name, press the Enter key. Figure 9.86. You can directly enter a fully qualified host name in the "Blocked hosts" list. Drag and drop a plain-text file listing the fully qualified host names separated by tabs or commas (Figure 9.87). Figure 9.87. You can drag and drop a text file into the "Blocked hosts" list.
6.	When you've finished making changes, click the Save button .

Tips

• When you're dragging a text file to the "Blocked hosts" window, make sure there is a carriage return at the end of the last host name in the file. Otherwise, the last host-name entry will be ignored.

• It's important to remember that proxy settings won't affect any of your Web site settings.

• Client computers aren't, by default, configured to use a Web proxy. See the sidebar "Configuring a Web Proxy on Clients" for more information.

• Once they're configured, you should verify that sites are indeed blocked to your users.

• Any client that isn't configured to use your proxy server can bypass your list of blocked hosts. The best way to prevent this is to use a network firewall that only allows your proxy server to access external Web sites.