Cisco Systems ASA5515K9, ASA 5500 Configuring Regular Expressions

13-12
Cisco ASA 5500 Series Configuration Guide using the CLI
Chapter13 Configuring Objects
Configuring Regular Expressions
Feature History for Objects and Groups
Table 1 lists each feature change and the platform release in which it was implemented.
Configuring Regular Expressions
A regular expression matches text strings either literally as an exact string, or by using metacharacters
so that you can match multiple variants of a text string. You can use a regular expression to match the
content of certain application traffic; for example, you can match a URL string inside an HTTP packet.
This section describes how to create a regular expression and includes the following topics:
•Creating a Regular Expression, page13-12
•Creating a Regular Expression Class Map, page13-15
Creating a Regular Expression
A regular expression matches text strings either literally as an exact string, or by using metacharacters
so you can match multiple variants of a text string. You can use a regular expression to match the content
of certain application traffic; for example, you can match a URL string inside an HTTP packet.
Guidelines
Use Ctrl+V to escape all of the special characters in the CLI, such as question mark (?) or a tab. For
example, type d[Ctrl+V]?g to enter d?g in the configuration.
See the regex command in the command reference for performance impact information when matching
a regular expression to packets.
Note As an optimization, the ASA searches on the deobfuscated URL. Deobfuscation compresses multiple
forward slashes (/) into a single slash. For strings that commonly use double slashes, like “http://”, be
sure to search for “http:/” instead.
Table1 Feature History for Object Groups
Feature Name Releases Feature Information
Object groups 7.0(1) Object groups simplify access list creation and
maintenance.
We introduced or modified the following commands:
object-group protocol, object-group network,
object-group service, object-group icmp_type.
Objects 8.3(1) Object support was introduced.
We introduced or modified the following commands:
object-network, object-service, object-group network,
object-group service, network object, access-list
extended, access-list webtype, access-list remark.