Cisco Cisco Web Security Appliance S170 ユーザーガイド

All policy groups define which transactions apply to them. When a client sends a request to a server, the 
Web Proxy receives the request, evaluates it, and determines to which policy group it belongs. The Web 
Proxy applies the configured policy control settings to a client request based on the client request’s 
policy group membership. 

Transactions belong to a policy group for each type of policy that is enabled. If a policy type has no user 
defined policy groups, then each transaction belongs to the global policy group for that policy type.

Policy group membership for a Routing, Decryption, Access, Data Security, and External DLP Policies 
is based on an Identity and optional additional criteria. That means that the Web Proxy evaluates Identity 
groups before the other policy types. The Web Security appliance allows you to define some membership 
criteria at either the Identity level or the non-Identity policy level. For more information, see 

Suppose you define an Identity by subnet 10.1.1.0/24 and then create an Access Policy using that 
Identity. The Access Policy membership applies to all IP addresses specified in the Identity by default. 
You can then choose to configure the Access Policy membership so that it applies to a subset of the 
addresses defined in the Identity, such as addresses 10.1.1.0-15.

For more information defining membership for each policy type, see the following sections:

The Web Security appliance separates where it authenticates users from where it authorizes users. 

Authentication is the mechanism by which the Web Proxy securely identifies a user. It answers the 
following questions:

Who is the user? 

Is the user really whom he/she claims to be?

Authorization is the mechanism by which the Web Proxy determines the level of access the user has to 
the World Wide Web. It answers the following questions:

Is this user allowed to view this website?

Is this user allowed to connect to this HTTPS server without the connection being decrypted? 

Is this user allowed to directly connect to the web server, or must it connect to another proxy server 
first?

Is this user allowed to upload this data?

The Web Proxy can only authorize a user to access an Internet resource after it authenticates who the 
user is. The Web Proxy authenticates users when it evaluates Identity groups, and it authorizes users 
when it evaluates all other policy group types. What that means is the Identity group indicates who is 
making the request, but does not indicate whether that client is allowed to make the request.