Cisco Cisco Web Security Appliance S160 Guía Del Usuario
9-20
AsyncOS 8.8 for Cisco Web Security Appliances User Guide
Chapter 9 Classify URLs for Policy Application
Regular Expressions
Access Log File
The access log file records the URL category for each transaction in the scanning verdict information
section of each entry.
section of each entry.
Related Topics
•
•
.
Regular Expressions
The Web Security appliance uses a regular expression syntax that differs slightly from the regular
expression syntax used by other Velocity pattern-matching engine implementations. Further, the
appliance does not support using a backward slash to escape a forward slash. If you need to use a forward
slash in a regular expression, simply type the forward slash without a backward slash.
expression syntax used by other Velocity pattern-matching engine implementations. Further, the
appliance does not support using a backward slash to escape a forward slash. If you need to use a forward
slash in a regular expression, simply type the forward slash without a backward slash.
Note
Technically, AsyncOS for Web uses the Flex regular expression analyzer. For more detailed information
about how it reads regular expressions, see http://flex.sourceforge.net/manual/Patterns.html.
about how it reads regular expressions, see http://flex.sourceforge.net/manual/Patterns.html.
You can use regular expressions in the following locations:
•
Custom URL categories for Access Policies. When you create a custom URL category to use with
Access Policy groups, you can use regular expressions to specify multiple web servers that match
the pattern you enter.
Access Policy groups, you can use regular expressions to specify multiple web servers that match
the pattern you enter.
•
Custom user agents to block. When you edit the applications to block for an Access Policy group,
you can use regular expressions to enter specific user agents to block.
you can use regular expressions to enter specific user agents to block.
Note
Regular expressions that perform extensive character matching consume resources and can affect system
performance. For this reason, regular expressions should be cautiously applied.
performance. For this reason, regular expressions should be cautiously applied.
Related Topics
•
•
Policy: Protocols and User Agents, page 9-13
Forming Regular Expressions
Regular expressions are rules that typically use the word “matches” in the expressions. They can be
applied to match specific URL destinations or web servers. For example, the following regular
expression matches any pattern containing blocksite.com:
applied to match specific URL destinations or web servers. For example, the following regular
expression matches any pattern containing blocksite.com:
\.blocksite\.com
Consider the following regular expression example:
server[0-9]\.example\.com
In this example,
server[0-9]
matches
server0
,
server1
,
server2
, ...,
server9
in the domain
example.com
.