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Q153545: How to Pass Unsafe Characters in a URL

Article: Q153545
Product(s): Internet Information Server
Version(s): 1.0,2.0,3.0,4.0
Operating System(s): 
Keyword(s): 
Last Modified: 20-FEB-2002

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The information in this article applies to:

- Microsoft Internet Information Server versions 1.0, 2.0, 3.0, 4.0 
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SUMMARY
=======

It is possible to pass unsafe characters in a URL by encoding the characters
using the following syntax:

  % HEX

where HEX is the hexadecimal value of the unsafe character, for example, %2B.

MORE INFORMATION
================

For example: ASCII TABLE

+-----------------------+
| ASCII | HEX | ENCODED | 
+-----------------------+
| +     | 2B  | %2B     | 
+-----------------------+
| ?     | 3F  | %3F     | 
+-----------------------+

  + URL: http://server/scripts/script.idc?Param=2+2
  ENCODED URL: http://server/scripts/script.idc?Param=2%3F2

  ? URL: http://server/scripts/script.idc?Param=Who?
  ENCODED URL: http://server/scripts/script.idc?Param=Who%2B

RFC 1738 discusses "unsafe characters" in more detail below.

Unsafe:

  Characters can be unsafe for a number of reasons. The space character is
  unsafe because significant spaces may disappear and insignificant spaces may
  be introduced when URLs are transcribed or typeset or subjected to the
  treatment of word-processing programs. The chevron characters, < and >,
  are unsafe because they are used as the delimiters around URLs in free text;
  the quotation mark (""") is used to delimit URLs in some systems. The
  character # is unsafe and should always be encoded because it is used in
  World Wide Web and in other systems to delimit a URL from a fragment/anchor
  identifier that might follow it. The character % is unsafe because it is used
  for encodings of other characters. Other characters are unsafe because
  gateways and other transport agents are known to sometimes modify such
  characters. These characters are {, }, |, \, ^, ~, [, ], and `.

  All unsafe characters must always be encoded within a URL. For example, the
  character # must be encoded within URLs even in systems that do not normally
  deal with fragment or anchor identifiers, so that if the URL is copied into
  another system that does use them, it will not be necessary to change the URL
  encoding.

Additional query words: iis encode dangerous unsafe url HREF

======================================================================
Keywords          :  
Technology        : kbiisSearch kbiis400 kbiis300 kbiis200 kbiis100
Version           : :1.0,2.0,3.0,4.0
Issue type        : kbhowto

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