For your Red Hat Linux proxy server to provide Web-browsing access (HTTP) to the Windows and Red Hat Linux client computers on your network, each client needs to do a bit of set up within the Web browser. The beauty of using proxy servers is in what your client computers don't need to know, such as the following:
Addresses of DNS servers
Telephone numbers of ISPs
Chat scripts to connect to the ISP
There are probably other things that clients don't need to know, but you get the idea. After the proxy server has a connection to the Internet and has allowed a client computer on the LAN access to that service, all the client needs to know is the following:
Host name — The name or IP address of the proxy server. (This assumes that the client can reach the proxy over the company's LAN or other IP-based network.)
Port numbers — The port number of the HTTP service (3128 by default). That same port number can be used for FTP and gopher services as well.
How you go about setting up proxy service on the client has more to do with the browser you are using than with the operating system you are using. Follow the procedures below for setting up Mozilla, Microsoft Internet Explorer, Mosaic, or Lynx browsers.
Normally, you would set up Mozilla to browse the Web over a TCP/IP connection to the Internet (over telephone lines or via a router on your LAN). Follow this procedure to change Mozilla to access the Web through your proxy server:
Choose Edit ? Preferences. The Preferences window appears.
Next to the Advanced category, click the plus sign and select Proxies.
Click Manual proxy configuration. The Proxies window appears as shown in Figure 16-3.
Figure 16-3: The Preferences window identifies proxy servers and port numbers in Mozilla.
Type the proxy server's name or IPaddress in the address boxes for HTTP, FTP, and Gopher services.
Type the port number for HTTP services on your proxy server (probably 3128) in the Port boxes for HTTP, FTP, and Gopher services.
The next time you request a Web address from Mozilla, it will contact the proxy server to try to obtain the content.
To configure Internet Explorer to use a proxy server to get to the Web, you need to change a few Internet options. Follow the procedure below:
Open the Internet Explorer window.
Choose View (or Tools) ? Internet Options. The Internet Options window appears.
Click the Connections tab.
Assuming you have a LAN already configured, click Local Area Network and then click LAN Settings. The Local Area Network Settings window should appear, as shown in Figure 16-4.
Figure 16-4: The Local Area Network Settings window lets you add proxies to Internet Options in Internet Explorer.
Click the Use a proxy server box so a check mark appears.
Type the address of the proxy server and the port number for HTTP services (probably 3128).
MS Internet Explorer assumes that the same ports are used for HTTP, Gopher, and FTP services. If this is not true, click Advanced and change the port numbers for each service accordingly.
Click OK (in the Local Area Network Settings window) and OK again (in the Internet Options window).
The next time you try to access the Web from Internet Explorer, it will try to do so through the proxy server you defined.
To have a Mosaic or Lynx browser use a proxy server to access the Internet, add an environment variable to the shell where the browser will run. Here's how you would set the environment variables for HTTP, Gopher, and FTP proxy services to a proxy computer named maple using a csh or tcsh shell:
setenv http_proxy http://maple:3128/ setenv gopher_proxy http://maple:3128/ setenv ftp_proxy http://maple:3128/
If you are using a ksh or bash shell, type the following:
export http_proxy=http://maple:3128 export gopher_proxy=http://maple:3128 export ftp_proxy=http://maple:3128
You can add any of these values to your start-up scripts. Or to make them available on a system-wide basis, you could add them to a system configuration file, such as /etc/profile or /etc/skel/.bash_profile.