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19-11
Cisco ASDM User Guide
OL-16647-01
Chapter 19 Adding Global Objects
Configuring Regular Expressions
• Build—Helps you build a regular expression using the Build Regular Expression dialog box.
• Test—Tests a regular expression against some sample text.
Modes
The following table shows the modes in which this feature is available:
Build Regular Expression
The Build Regular Expression dialog box lets you construct a regular expression out of characters and
metacharacters. Fields that insert metacharacters include the metacharacter in parentheses in the field
name.
Note As an optimization, the security appliance 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.
Fields
Build Snippet—This area lets you build text snippets of regular text or lets you insert a metacharacter
into the Regular Expression field.
• Starts at the beginning of the line (^)—Indicates that the snippet should start at the beginning of a
line, using the caret (^) metacharacter. Be sure to insert any snippet with this option at the beginning
of the regular expression.
• Specify Character String—Enter a text string manually.
char Character When character is not a metacharacter, matches the
literal character.
\r Carriage return Matches a carriage return 0x0d.
\n Newline Matches a new line 0x0a.
\t Tab Matches a tab 0x09.
\f Formfeed Matches a form feed 0x0c.
\xNN Escaped hexadecimal number Matches an ASCII character using hexadecimal (exactly
two digits).
\NNN Escaped octal number Matches an ASCII character as octal (exactly three
digits). For example, the character 040 represents a
space.
Table 19-1 regex Metacharacters (continued)
Character Description Notes
Firewall Mode Security Context
Routed Transparent Single
Multiple
Context System
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