Cisco Cisco Web Security Appliance S190 Guía Del Usuario
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Cisco IronPort AsyncOS 7.0 for Web User Guide
OL-23079-01
Chapter 5 Web Proxy Services
Working with PAC Files
•
Web server. You can place the PAC file on a web server that each client
machine can access. For example, you can place the PAC file on an Apache
or Microsoft IIS web server. Enter the URL in the browser configuration.
machine can access. For example, you can place the PAC file on an Apache
or Microsoft IIS web server. Enter the URL in the browser configuration.
•
Web Security appliance. You can place the PAC file on the Web Security
appliance. You might want to put the PAC file on the Web Security appliance
to verify every client machine can access it within the network. Enter the URL
in the browser configuration.
appliance. You might want to put the PAC file on the Web Security appliance
to verify every client machine can access it within the network. Enter the URL
in the browser configuration.
For more information about uploading PAC files to the Web Security
appliance, see
appliance, see
.
Detecting the PAC File Location Automatically
If a browser supports the Web Proxy Autodiscovery Protocol (WPAD), you can
configure it to automatically detect the PAC file location. WPAD is a protocol that
allows the browser determine the location of the PAC file using DHCP and DNS
lookups.
configure it to automatically detect the PAC file location. WPAD is a protocol that
allows the browser determine the location of the PAC file using DHCP and DNS
lookups.
Before fetching its first page, a web browser configured to automatically detect
the PAC file location tries to find the PAC file using DHCP or DNS. Therefore, to
use WPAD, you must set up either a DHCP server or a DNS server to direct web
browser requests to the PAC file on a network server. However, not all browsers
support DHCP to find the PAC file using WPAD.
the PAC file location tries to find the PAC file using DHCP or DNS. Therefore, to
use WPAD, you must set up either a DHCP server or a DNS server to direct web
browser requests to the PAC file on a network server. However, not all browsers
support DHCP to find the PAC file using WPAD.
This section includes some general guidelines for using WPAD with DNS “A”
records. For more detailed information, or for information about using WPAD
with DHCP, see the following locations:
records. For more detailed information, or for information about using WPAD
with DHCP, see the following locations:
•
http://en.wikipedia.org/wiki/Web_Proxy_Autodiscovery_Protocol
•
http://www.wpad.com/draft-ietf-wrec-wpad-01.txt
•
http://www.microsoft.com/technet/isa/2004/plan/automaticdiscovery.mspx
When you use WPAD with DNS, each domain on the network can only use one
PAC file for all users on a domain because only domain name can uniquely
identify a PAC file using DNS. For example, users on
host1.accounting.example.com and host2.finance.example.com can use different
PAC files.
PAC file for all users on a domain because only domain name can uniquely
identify a PAC file using DNS. For example, users on
host1.accounting.example.com and host2.finance.example.com can use different
PAC files.
To use WPAD with DNS:
Step 1
Rename the PAC file to wpad.dat.