Using Pattern-Matching Syntax in NPS

Updated: October 21, 2008

Applies To: Windows Server 2008, Windows Server 2008 R2

Network Policy Server (NPS) in Windows Server 2008 supports the use of regular expressions for pattern matching. You can use this syntax to specify the conditions of network policy attributes and Remote Authentication Dial-In User Service (RADIUS) realms.

You can use the following table as a reference source when creating regular expressions with pattern-matching syntax.

 

Character Description Example

\

Marks the next character as a character to match.

/n/ matches the character "n". The sequence /\n/ matches a line feed or newline character.

^

Matches the beginning of the input or line.

 

$

Matches the end of the input or line.

 

*

Matches the preceding character zero or more times.

/zo*/ matches either "z" or "zoo."

+

Matches the preceding character one or more times.

/zo+/ matches "zoo" but not "z."

?

Matches the preceding character zero or one times.

/a?ve?/ matches the "ve" in "never."

.

Matches any single character except a newline character.

 

( pattern )

Matches pattern and remembers the match. To match ( ) (parentheses), use "\(" or "\)".

 

x | y

Matches either x or y.

/z|food?/ matches "zoo" or "food."

{ n }

Matches exactly n times (n is a nonnegative integer).

/o{2}/ does not match the "o" in "Bob," but matches the first two instances of the letter o in "foooood."

{ n ,}

Matches at least n times (n is a nonnegative integer).

/o{2,}/ does not match the "o" in "Bob" but matches all of the instances of the letter o in "foooood." /o{1,}/ is equivalent to /o+/.

{ n , m }

Matches at least n and at most m times (m and n are nonnegative integers).

/o{1,3}/ matches the first three instances of the letter o in "fooooood."

[ xyz ]

Matches any one of the enclosed characters (a character set).

/[abc]/ matches the "a" in "plain."

[^ xyz ]

Matches any characters that are not enclosed (a negative character set).

/[^abc]/ matches the "p" in "plain."

\b

Matches a word boundary (for example, a space).

/ea*r\b/ matches the "er" in "never early."

\B

Matches a nonword boundary.

/ea*r\B/ matches the "ear" in "never early."

\d

Matches a digit character (equivalent to [0-9]).

 

\D

Matches a nondigit character (equivalent to [^0-9]).

 

\f

Matches a form feed character.

 

\n

Matches a line feed character.

 

\r

Matches a carriage return character.

 

\s

Matches any white space character including space, tab, and form feed (equivalent to [ \f\n\r\t\v]).

 

\S

Matches any non-white space character (equivalent to [^ \f\n\r\t\v]).

 

\t

Matches a tab character.

 

\v

Matches a vertical tab character.

 

\w

Matches any word character, including underscore (equivalent to [A-Za-z0-9_]).

 

\W

Matches any nonword character, excluding underscore (equivalent to [^A-Za-z0-9_]).

 

\ num

Refers to remembered matches (?num, where num is a positive integer). For example, \1 replaces what is stored in the first remembered match. This option can be used only in the Replace text box when configuring attribute manipulation.

 

/ n /

Allows the insertion of ASCII codes into regular expressions (?n, where n is an octal, hexadecimal, or decimal escape value).

 

The following examples describe the use of the pattern-matching syntax to specify network policy attributes:

  • To specify all phone numbers within the 899 area code, the syntax is:

    899.*

  • To specify a range of all IP addresses that begin with 192.168.1, the syntax is:

    192\.168\.1\..+

The following examples describe the use of the pattern-matching syntax to manipulate realm names for the User-Name attribute, which is located on the Attribute tab in the properties of a connection request policy.

  • To remove the realm portion of the User-Name attribute

    In an outsourced dial-up scenario in which an Internet service provider (ISP) routes connection requests to an organization NPS server, the ISP RADIUS proxy might require a realm name to route the authentication request. However, the NPS server might not recognize the realm name portion of the user name. Therefore, the realm name must be removed by the ISP RADIUS proxy before it is forwarded to the organization NPS server.

    • Find: @microsoft\.com

    • Replace:

  • To replace user@example.microsoft.com with example.microsoft.com\user

    • Find: (.*)@(.*)

    • Replace: $2\$1

  • To replace domain\user with specific_domain\user

    • Find: (.*)\\(.*)

    • Replace: specific_domain\$2

  • To replace user with user@specific_domain

    • Find: $

    • Replace: @specific_domain

You can create routing rules that forward RADIUS messages with a specified realm name to a set of RADIUS servers when an NPS server is used as a RADIUS proxy. Following is a recommended syntax for routing requests based on realm name.

 

NetBIOS name Pattern

WCOAST

^wcoast\\

In the following example, wcoast.microsoft.com is a unique user principal name (UPN) suffix for the Domain Name System (DNS) or Active Directory Domain Services (AD DS) domain wcoast.microsoft.com. Using the supplied pattern, the NPS proxy can route messages based on domain network basic input/output system (NetBIOS) name or UPN suffix.

 

NetBIOS name UPN suffix Pattern

WCOAST

wcoast.microsoft.com

^wcoast\\|@wcoast\.microsoft\.com$

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