Export (0) Print
Expand All

MIME Types in ISA Server 2004

Multipurpose Internet Mail Extensions (MIME) is a standard covered in RFC 822, RFC 1521, and RFC 1522. MIME types (also known as content types or media types) instruct a Web browser or mail application how to handle files received from a server. MIME provides a mechanism for sending a variety of file types as a part of an e-mail message, or attached to an e-mail message. To open and read such an attached file, an application installed on the receiving operating system must be associated with the file type (extension). For example, when a Web browser requests an item on a server, it also requests the MIME type of the object. Some MIME types, like graphics, can be displayed inside the browser. Others, such as word processing documents, require an external application to be displayed.

Content types in Microsoft Internet Security and Acceleration (ISA) Server 2004 specify MIME types and file name extensions. When you create an access rule, you can define it so that it applies to specific content types. This enables you to configure granular security policies by limiting access to specific types of content.

Content Types

Link Translation and Content Types

Appendix A: Default MIME Type Associations for IIS

Additional Resources

When you use content types in ISA Server access rules, content type parameters specified in a rule are only applied to Hypertext Transfer Protocol (HTTP) and tunneled File Transfer Protocol (FTP) traffic that passes through ISA Server. Content types do not apply to any other protocol, such as HTTPS. HTTP and FTP tunneled traffic is processed as follows:

  • When a client requests HTTP content, ISA Server sends the request to the Web server. When the Web server returns the object, ISA Server checks the object's MIME type or its file name extension, depending on the header information returned by the Web server. ISA Server determines if a rule applies to a content type that includes the requested file name extension, and processes the rule accordingly.
  • When a client requests FTP content, ISA Server checks the file name extension of the requested object. ISA Server determines if a rule applies to a content type that includes the requested file name extension, and processes the rule accordingly.

Creating Content Types

ISA Server provides predefined content types, including:

  • Application
  • Application data files
  • Audio
  • Compressed files
  • Documents
  • HTML documents
  • Images
  • Macro documents
  • Text
  • Video
  • VRML

You can create your own content types. Common content types you may want to add include:

  • Common Windows media types:
    • .wma (Windows media audio)
    • .wmv (Windows media video)
    • .asf (either audio or video)
  • Potentially dangerous files:
    • .jse (encoded JScript)
    • .vbe (encoded VBScript)
    • .wsf (Windows Script file)
    • .reg (Windows registry file)
    • .pl (PERL script)
    • .com (executable)

When you create content types, we recommend that you specify the content's MIME type and file name extension. For example, to include all directory files in a content type, select the following file name extensions and MIME types:

  • .dir
  • .dxr
  • .dcr
  • application/x-director

When you configure a content type and specify the MIME type, you can use an asterisk (*) as a wildcard character. For example, to include all application types, enter application/*. The asterisk wildcard character can be used only with MIME types (and not with file extensions). The asterisk can be specified only once, at the end of the MIME type after the slash mark (/).

Depending on the Web server, different MIME types are associated with different file name extensions. A list of the default associations for Internet Information Services (IIS) is provided in Appendix A.

To create a content type, use the following steps.

  1. In the console tree of ISA Server Management, click Firewall Policy.
  2. In the task pane, on the Toolbox tab, click Content Types.
  3. On the toolbar beneath Content Types, click New to open the New Content Type Set dialog box.
  4. In Name, type the name of the content type.
  5. (Optional) In Description, type a description for the content type.
  6. In Available types, do one of the following:
    • To select an existing content type, select a file name extension or MIME type from the drop-down list, and then click Add.
    • To add a new content type, type a new file name extension or a MIME type, and then click Add.
    Note:
    You can use an asterisk (*) as a wildcard character. For example, to include all application types, enter application/*.To remove a file name extension or MIME type from the content type, in Selected types, click the file name extension or MIME type, and then click Remove.

Some published websites may include references to internal computer names. Because only ISA Server is available to external clients, and not computers on the Internal network, these references will appear as broken links. ISA Server has a link translation Web filter that enables you to create a dictionary of definitions for internal computer names that map to publicly known names. When you enable link translation for a Web publishing rule, a link translation dictionary is automatically created. You can add more entries to this default dictionary if required.

The link translation filter checks the Content-type header of the request response to determine whether it needs to perform translation on the body of the message. By default, link translation only operates on the HTML documents content group, but you can specify other groups. If no Content-type header is present, the filter will look for a Content-location header to perform translation. If neither header is present, the filter will look at the file name extension of the requested URL.

Note:
When the Outlook Web Access server or the ISA Server computer listens for requests on nonstandard ports, and the configured bridging mode is Secure connection to mail server, you must enable link translation for a content type that includes the following:
  • application/x-javascript
  • text/css
  • text/x-component
  • text/xml
  • .eml
  • .css

You must create a new content type, or modify an existing content type, to include these file and MIME types.

Depending on the Web server, different MIME types are associated with different file name extensions. The following table lists the Internet Information Services (IIS) default associations.

File name extension MIME type

.hta

application/hta

.isp

application/x-internet-signup

.crd

application/x-mscardfile

.pmc

application/x-perfmon

.spc

application/x-pkcs7-certificates

.sv4crc

application/x-sv4crc

.bin

application/octet-stream

.clp

application/x-msclip

.mny

application/x-msmoney

.p7r

application/x-pkcs7-certreqresp

.evy

application/envoy

.p7s

application/pkcs7-signature

.eps

application/postscript

.setreg

application/set-registration-initiation

.xlm

application/vnd.ms-excel

.cpio

application/x-cpio

.dvi

application/x-dvi

.p7b

application/x-pkcs7-certificates

.doc

application/msword

.dot

application/msword

.p7c

application/pkcs7-mime

.ps

application/postscript

.wps

application/vnd.ms-works

.csh

application/x-csh

.iii

application/x-iphone

.pmw

application/x-perfmon

.man

application/x-troff-man

.hdf

application/x-hdf

.mvb

application/x-msmediaview

.texi

application/x-texinfo

.setpay

application/set-payment-initiation

.stl

application/vndms-pkistl

.mdb

application/x-msaccess

.oda

application/oda

.hlp

application/winhlp

.nc

application/x-netcdf

.sh

application/x-sh

.shar

application/x-shar

.tcl

application/x-tcl

.ms

application/x-troff-ms

.ods

application/oleobject

.axs

application/olescript

.xla

application/vnd.ms-excel

.mpp

application/vnd.ms-project

.dir

application/x-director

.sit

application/x-stuffit

.*

application/octet-stream

.crl

application/pkix-crl

.ai

application/postscript

.xls

application/vnd.ms-excel

.wks

application/vnd.ms-works

.ins

application/x-internet-signup

.pub

application/x-mspublisher

.wri

application/x-mswrite

.spl

application/futuresplash

.hqx

application/mac-binhex40

.p10

application/pkcs10

.xlc

application/vnd.ms-excel

.xlt

application/vnd.ms-excel

.dxr

application/x-director

.js

application/x-javascript

.m13

application/x-msmediaview

.trm

application/x-msterminal

.pml

application/x-perfmon

.me

application/x-troff-me

.wcm

application/vnd.ms-works

.latex

application/x-latex

.m14

application/x-msmediaview

.wmf

application/x-msmetafile

.cer

application/x-x509-ca-cert

.zip

application/x-zip-compressed

.p12

application/x-pkcs12

.pfx

application/x-pkcs12

.der

application/x-x509-ca-cert

.pdf

application/pdf

.xlw

application/vnd.ms-excel

.texinfo

application/x-texinfo

.p7m

application/pkcs7-mime

.pps

application/vnd.ms-powerpoint

.dcr

application/x-director

.gtar

application/x-gtar

.sct

text/scriptlet

.fif

application/fractals

.exe

application/octet-stream

.ppt

application/vnd.ms-powerpoint

.sst

application/vndms-pkicertstore

.pko

application/vndms-pkipko

.scd

application/x-msschedule

.tar

application/x-tar

.roff

application/x-troff

.t

application/x-troff

.prf

application/pics-rules

.rtf

application/rtf

.pot

application/vnd.ms-powerpoint

.wdb

application/vnd.ms-works

.bcpio

application/x-bcpio

.dll

application/x-msdownload

.pma

application/x-perfmon

.pmr

application/x-perfmon

.tr

application/x-troff

.src

application/x-wais-source

.acx

application/internet-property-stream

.cat

application/vndms-pkiseccat

.cdf

application/x-cdf

.tgz

application/x-compressed

.sv4cpio

application/x-sv4cpio

.tex

application/x-tex

.ustar

application/x-ustar

.crt

application/x-x509-ca-cert

.ra

audio/x-pn-realaudio

.mid

audio/mid

.au

audio/basic

.snd

audio/basic

.wav

audio/wav

.aifc

audio/aiff

.m3u

audio/x-mpegurl

.ram

audio/x-pn-realaudio

.aiff

audio/aiff

.rmi

audio/mid

.aif

audio/x-aiff

.mp3

audio/mpeg

.gz

application/x-gzip

.z

application/x-compress

.tsv

text/tab-separated-values

.xml

text/xml

.323

text/h323

.htt

text/webviewhtml

.stm

text/html

.html

text/html

.xsl

text/xml

.htm

text/html

.cod

image/cis-cod

.ief

image/ief

.pbm

image/x-portable-bitmap

.tiff

image/tiff

.ppm

image/x-portable-pixmap

.rgb

image/x-rgb

.dib

image/bmp

.jpeg

image/jpeg

.cmx

image/x-cmx

.pnm

image/x-portable-anymap

.jpe

image/jpeg

.jfif

image/pjpeg

.tif

image/tiff

.jpg

image/jpeg

.xbm

image/x-xbitmap

.ras

image/x-cmu-raster

.gif

image/gif

To learn more about MIME types on Microsoft.com, see the following resources:

Was this page helpful?
(1500 characters remaining)
Thank you for your feedback
Show:
© 2014 Microsoft