Cisco Cisco Web Security Appliance S380 Guida Utente
C R E A T I N G A P A C F I L E F O R R E M O T E U S E R S
C H A P T E R 5 : W E B P R O X Y S E R V I C E S
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However, you can make PAC files more complex. For example, you can create a PAC file that
instructs the browser to connect directly to the website under certain conditions, such as
matching on a particular host name or IP address, and to use the proxy server in all other
cases. You can create a PAC file that instructs applications to go directly to the website for
servers on your intranet.
instructs the browser to connect directly to the website under certain conditions, such as
matching on a particular host name or IP address, and to use the proxy server in all other
cases. You can create a PAC file that instructs applications to go directly to the website for
servers on your intranet.
For more information about creating and using PAC files, see the following locations:
• http://en.wikipedia.org/wiki/Proxy_auto-config
• http://www.mozilla.org/catalog/end-user/customizing/enduserPAC.html
• http://wp.netscape.com/eng/mozilla/2.0/relnotes/demo/proxy-live.html
Note — Common convention is to use the .pac file extension for PAC file names.
Creating a PAC File for Remote Users
Some laptop users connect to the Internet both from inside your organization’s network and
outside the network. For these users, you can create a PAC file that informs the browser to
connect to the Web Proxy when they are on the network, and to connect directly to web
servers when they are not on the network.
outside the network. For these users, you can create a PAC file that informs the browser to
connect to the Web Proxy when they are on the network, and to connect directly to web
servers when they are not on the network.
To do this, make sure the PAC file is hosted on a web server that is DNS resolvable inside the
network, but not DNS resolvable outside the network. This works because when you enter a
URL for the PAC file location, the browser will always try to use the PAC file in the configured
location. If the browser cannot resolve the URL, such as when it is outside the network, it tries
to access all web sites directly instead. Then when the laptop connects to the network again,
the browser can access the PAC file and will use the Web Proxy to access web sites.
network, but not DNS resolvable outside the network. This works because when you enter a
URL for the PAC file location, the browser will always try to use the PAC file in the configured
location. If the browser cannot resolve the URL, such as when it is outside the network, it tries
to access all web sites directly instead. Then when the laptop connects to the network again,
the browser can access the PAC file and will use the Web Proxy to access web sites.
Specifying the PAC File in Browsers
To use a PAC file, you must publish the PAC file in a location that can be accessed by each
browser that needs to access it. When you configure a browser to use a PAC file, you can use
either of the following methods:
browser that needs to access it. When you configure a browser to use a PAC file, you can use
either of the following methods:
• Enter the PAC file location. See “Entering the PAC File Location” on page 85.
• Detect the PAC file location automatically. See “Detecting the PAC File Location
Entering the PAC File Location
You can configure a browser to use a PAC file by specifying the exact location of the file. You
might want to enter the exact PAC file location for laptop users who might need to use
different proxy servers depending on their current location.
might want to enter the exact PAC file location for laptop users who might need to use
different proxy servers depending on their current location.
You can place the PAC file in the following locations:
• Local machine. You can place the PAC file on each client machine and configure the
browsers to use it. You might want to use a local PAC file to test a PAC file before
deploying it to the entire organization. Enter the path in the browser configuration. The
path you enter depends on the browser type.
deploying it to the entire organization. Enter the path in the browser configuration. The
path you enter depends on the browser type.