Configuring Client Browsers

Squid supports both standard proxy caches and transparent caches. With a standard proxy cache, users will need to configure their browsers to specifically access the Squid server. A transparent cache, on the other hand, requires no browser configuration by users. The cache is transparent, allowing access as if it were a normal Web site. Transparent caches are implemented by IPtables using net filtering to intercept requests and direct them to the proxy cache (see Chapter 19).

With a standard proxy cache, users need to specify their proxy server in their Web browser configuration. For this they will need the IP address of the host running the Squid proxy server as well as the port it is using. Proxies usually make use of port 3128. To configure use of a proxy server running on the local sample network described in Chapter 5, you would enter the following. The proxy server is running on turtle.mytrek.com (192.168.0.1) and using port 3128.

192.168.0.1 3128

On Mozilla and Netscape, the user on the sample local network would first select the Proxy panel located in Preferences under the Edit menu. Then, in the Manual proxy configuration's View panel, enter the previous information. The user will see entries for FTP, Gopher, HTTP, and Security proxies. For standard Web access, enter the IP address in the FTP, Gopher, and Web boxes. For their port boxes, enter 3128.

For GNOME, select Network Proxy in the Preferences menu or window, and for Konqueror on the KDE Desktop, select the Proxies panel on the Preferences | Web Browsing menu window.

Here, you can enter the proxy server address and port numbers.

If your local host is using Internet Explorer (such as a Windows system does), you set the proxy entries in the Local Area Network settings accessible from the Internet Options window.

On Linux or Unix systems, local hosts can set the http_proxy, gopher_proxy and ftp_proxy shell variables to configure access by Linux-supported Web browsers such as lynx. You can place these definitions in your .bash_profile or /etc/profile file to have them automatically defined whenever you log in.

http_proxy=192.168.0.1:3128
ftp proxy=192.168.0.1:3128
gopher_proxy=192.168.0.1:3128
export http_proxy ftp_proxy gopher_proxy

Before a client on a local host could use the proxy server, access permission would have to be given to it in the server's squid.conf file, described in the later section "Security." Access can easily be provided to an entire network. For the sample network used here, you would have to place the following entries in the squid.conf file. These are explained in detail in the following sections.

acl mylan src 192.168.0.0/255.255.255.0
http_access allow mylan

Tip

Web clients that need to access your Squid server as a standard proxy cache will need to know the server's address and the port for Squid's HTTP services, by default 3128.