If you ever use your Mac on a large network such as at work, at a university or at a library, you will probably need to set up a proxy. Networks use proxies to control and limit access from unauthorized users to unauthorized content. In addition, proxies make network speeds faster because a proxy server stores information from previous visits to the cache. When that site is revisited, the proxy will compare the old information with the new information. Because the network does not have to reload each page fresh, the network will be faster. Because most large organizations use PCs, it is sometimes difficult to find an administrator who knows how set up a proxy on a Mac.
Open Network Preferences
To set up a proxy using Mac Leopard, open your system preferences and select "Network." Select "Internet Connection." Click on the network that you are using; it usually has a green circle next to it. Then, click on "Advanced..." Click on the "Proxies" tab.
Enter the Proxy Information
Change the "Configuration Proxies" drop-down box to "manually," unless you are using a PAC file. A PAC file is used to limit access to the Internet. For example, a business will limit what websites its employees can visit. In the box labeled "Select a protocol to configure," select the protocols that you want to use with the proxy or proxies. Then, configure each protocol by entering the "FTP Proxy Server" address and the password if required. Note that each protocol must be configured separately. Once the proxies are configured, you can enter sites that do not need the proxy settings by entering the hosts and domains in the box labeled "Bypass proxy setting for these Hosts & Domains." If you need to turn off the proxy server, simply deselect the protocol from the "Select a protocol to configure" box. The proxy server will remain configured in case you need to use the proxy later.