Cisco ASA 5505 Configuration Manual page 321

Chapter 13 Configuring Objects
Building a Regular Expression
The Configuration > Global Objects > Regular Expressions > Add/Edit a Regular Expression > 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.
See
Detailed Steps
Build Snippet—This area lets you build text snippets of regular text or lets you insert a metacharacter
into the Regular Expression field.
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•
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OL-20339-01
Table 13-1 on page 13-11
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.
Character String—Enter a text string.
–
Escape Special Characters—If you entered any metacharacters in your text string that you want
–
to be used literally, check this box to add the backslash (\) escape character before them. for
example, if you enter "example.com," this option converts it to "example\.com".
Ignore Case—If you want to match upper and lower case characters, this check box
–
automatically adds text to match both upper and lower case. For example, entering "cats" is
converted to "[cC][aA][tT][sS]".
Specify Character—Lets you specify a metacharacter to insert in the regular expression.
Negate the character—Specifies not to match the character you identify.
–
Any character (.)—Inserts the period (.) metacharacter to match any character. For example, d.g
–
matches dog, dag, dtg, and any word that contains those characters, such as doggonnit.
Character set—Inserts a character set. Text can match any character in the set. Sets include:
–
[0-9A-Za-z]
[0-9]
[A-Z]
[a-z]
[aeiou]
[\n\f\r\t] (which matches a new line, form feed, carriage return, or a tab)
For example, if you specify [0-9A-Za-z], then this snippet will match any character from A to
Z (upper or lower case) or any digit 0 through 9.
Special character—Inserts a character that requires an escape, including \, ?, *, +, |, ., [, (, or ^.
–
The escape character is the backslash (\), which is automatically entered when you choose this
option.
Whitespace character—Whitespace characters include \n (new line), \f (form feed), \r (carriage
–
return), or \t (tab).
Three digit octal number—Matches an ASCII character as octal (up to three digits). For
–
example, the character \040 represents a space. The backslash (\) is entered automatically.
for more information about metacharacters.
Cisco ASA 5500 Series Configuration Guide using ASDM
Configuring Regular Expressions
13-13