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Use ISA/TMG to distribute your custom WPAD configuration file

November 16th, 2011 No comments

In ISA 2006 SP1 and TMG RTM it’s possible to configure ISA/TMG to distribute
your own custom WPAD configuration file. This can be quite handy if you already
did write your own WPAD configuration file, which had been distributed on a
separate server, or if you want to use the ISA/TMG provided WPAD configuration
file as baseline for some changes, e.g. configure your clients to connect to the
NLB IP instead of using the Client CARP mechanism, which is used by ISA/TMG by
design.

To configure ISA/TMG to use your custom WPAD configuration file, you need to
follow these steps:

1. Please download the compressed file from http://www.isatools.org/tools/KB953293.zip
(Thanks Jim!)

2. Copy & Unzip die File on your ISA/TMG Server.

3. Copy the WPAD configuration file you want to distribute with your ISA/TMG
server to the ISA/TMG local hard drive.

4. Before you proceed importing the WPAD configuration file in your ISA/TMG
configuration, you have to make sure, that there are no non-ASCII Characters in
your WPAD configuration file, as the import process won’t import the complete
file if there are any non-ASCII characters included.

Note: if you use a WPAD configuration file which had been
distributed by ISA 2006, the file will most likely include non-ASCII Characters
at the end of the file.
To remove those characters you have to
delete this part:

function HashString(str, h){
for(var i=0; i<str.length; i++){
var c = str.charAt(i);
if(c
==’:’ || c == ‘/’) break;
c =
CharToAscii(c.toLowerCase());
h = (h
>>> 4) ^ h_tbl[(h ^ c) & 15];
h = (h >>> 4) ^ h_tbl[(h ^ (c>>>4)) & 15]; h
= MakeInt(h); } return h; }

and replace this part with those lines:

function HashString(str, h){
var hashstr=str.toLowerCase();
for(var i=0; i< hashstr.length; i++){
var c = hashstr.charAt(i);
if(c ==’:’ || c == ‘/’) break;
c = hashstr.charCodeAt(i);
h
= (h >>> 4) ^ h_tbl[(h ^ c) & 15];
h = (h >>> 4) ^ h_tbl[(h ^ (c>>>4)) & 15]; h
= MakeInt(h); } return h; }

afterwards you have to delete this line:

var Chars =”
!\”#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~€???????????Ž????????????ž?
¡¢£¤¥¦§¨©ª«¬¬®¯°±²³´µ¶•¸¹º»¼½¾¿ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõö÷øùúûüýþ
“; function CharToAscii(c){ return Chars.indexOf(c) + 32; }

5. After you prepared your WPAD configuration file, use the script attached
to import the file to the ISA/TMG configuration, e.g. by executing this command:

to operate on the current array, use ‘.’ as the array name or omit this
option:

cscript kb953293.wsf /array:. /net:internal /script:<FullPathToScript>

For a full list of options please refer to the readme.txt provided in the ZIP
file.

Remark: Please be aware, that any changes you configure in the ISA/TMG
UI will not be applied to the WPAD configuration file after you submit the
custom WPAD configuration file to your configuration. If you want to apply
changes to your WPAD configuration file once you’ve imported it to your
configuration, you have to manually edit the WPAD file and reimport it using the
script again.

If you want to stop using your custom WPAD configuration file and go back
using the ISA/TMG script you have to execute the following command:

cscript kb953293.wsf /array:arrayname /net:internal /del

Hope that helps!

Author

Philipp Sand
Microsoft CSS Forefront Security Edge Team

Technical Reviewer

Frank Heilmann
Microsoft CSS Forefront Security Edge Team

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