Cisco Cisco Web Security Appliance S670 User Guide
Chapter 5 Web Proxy Services
Working with PAC Files
5-20
Cisco IronPort AsyncOS 7.1 for Web User Guide
OL-23207-01
When you use a PAC file, you only need to configure each browser once with the
PAC file information. Then, you can edit the PAC file multiple times to add,
delete, or change Web Proxy connection information without editing each
browser. This way you can configure the proxy information about your network
in a centralized location and update it easily.
PAC file information. Then, you can edit the PAC file multiple times to add,
delete, or change Web Proxy connection information without editing each
browser. This way you can configure the proxy information about your network
in a centralized location and update it easily.
Note
Once a browser has read a PAC file, it stores it in memory for the remainder of the
browser session.
browser session.
You might want to use a PAC file for the following reasons:
•
Centralized management. You can manage the PAC file in a single, central
location.
location.
•
Complex network environment. If the network of proxy servers is
complicated, you can create a PAC file to accommodate different server and
client needs.
complicated, you can create a PAC file to accommodate different server and
client needs.
•
Changing network environment. If your network environment is likely to
change in the future, you can easily add, edit, or delete proxy servers in the
PAC and have the changes automatically affect all browsers.
change in the future, you can easily add, edit, or delete proxy servers in the
PAC and have the changes automatically affect all browsers.
•
Failover. If you have multiple proxy servers, you can provide redundancy in
case of failure. You can either program the PAC file to be redundant, or if a
failure occurs, change the PAC file to use a different proxy server.
case of failure. You can either program the PAC file to be redundant, or if a
failure occurs, change the PAC file to use a different proxy server.
Note
Different browsers take different amounts of time to fail over to a
secondary proxy. For example, Internet Explorer takes about 25 seconds,
and Firefox takes about 50 seconds.
secondary proxy. For example, Internet Explorer takes about 25 seconds,
and Firefox takes about 50 seconds.
•
Load balancing. If you have multiple proxy servers, you can use the PAC file
to specify which requests go to which proxy server. For example, you might
want users on one subnet to use a particular proxy and users on a different
subnet to use a different proxy.
to specify which requests go to which proxy server. For example, you might
want users on one subnet to use a particular proxy and users on a different
subnet to use a different proxy.