Cisco Cisco Web Security Appliance S170 사용자 가이드

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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 “Policy Group Membership Rules and Guidelines” on 
page 115.
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:
Authenticating Users versus Authorizing Users
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?