If your computer connects to the Internet through a network protected by a firewall, you may need to specify proxy servers to get to webpages and other Internet resources.
Before you begin, ask your network administrator to tell you which type of proxy server to specify (for example, a web proxy server), the IP address or DNS name for the server, and a port number.
Choose Safari > Preferences and click Advanced.
Click Change Settings.
The Network pane of System Preferences opens.
Use the information you got from your network administrator to change the proxy settings.
The server is called a “proxy” because Safari sends requests for webpages to the server instead of directly to the website.