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WPAD issue - 14.Feb.2006 3:00:17 PM

zdgcook

Posts: 7
Joined: 14.Feb.2006
Status: offline

Hello

I am attempting to setup DHCP auto configuration with ISA server 2004 using just the WEB proxy client. I have sucessfully reached the point where my DHCP server is supplying the correct URL for the wpad.dat file, but when IE makes the call to download the file it is stripping the last character off of file name in the get request. I have confirmed this with a sniffer trace and see the get request as "get /wpad.da HTTP/1.1" instead of get/wpad.dat HTTP/1.1". I have confirmed in the sniffer trace that the DHCP server has the correct text string and is providing it to the client in the DHCP ACK. I have been searching for information if this is a known issue with some versions of IE, but have not found any information on the issue yet. The version of IE I am testing with is 6.0 sp2. I did my initial testing on ISA server 2004 SP1 running on Windows server 2003 SP1 and have upgraded to ISA server 2004 SP2 with the same results. Is anyone else experiencing this issue or know of a fix or work around. Thank you.

Dave

Post #: 1

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RE: WPAD issue - 14.Feb.2006 3:04:39 PM

LLigetfa

Posts: 2184
Joined: 10.Aug.2004
From: fort frances.on.ca
Status: offline

Can you post your option 252 *exactly* the way you entered it?
If you enter that exact URL in your browser, what do you get?

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(in reply to zdgcook)

Post #: 2

RE: WPAD issue - 14.Feb.2006 3:14:57 PM

zdgcook

Posts: 7
Joined: 14.Feb.2006
Status: offline

I have tried using the internal publish ability of my test ISA server with a host name of ointps06 with the following 252 option:

http://ointps06.owens-ill.com:80/wpad.dat

And have now setup a web server on a seperate 2003 SP1 server using the following 252 option:

http://oints046.owens-ill.com:80/wpad.dat

On both configurations I can directly access the wpad file by pasting the above URLs in the browser. Also if I paste either of the above URLs in the "use automatic configuration script" area of IE's browser settings they work correctly. It only fails when IE is using the Automatically detect settings feature.

Thanks for your reply.

(in reply to LLigetfa)

Post #: 3

RE: WPAD issue - 14.Feb.2006 3:35:27 PM

ClintD

Posts: 1833
Joined: 26.Jan.2001
From: Keller, TX
Status: offline

Can you post the HTTP portion of the capture? That's really weird... I wonder if Stefaan ever ran into this when he made his WPAD articles?

I'd think it's more of an IE problem than anything else...

(in reply to zdgcook)

Post #: 4

RE: WPAD issue - 14.Feb.2006 4:13:14 PM

zdgcook

Posts: 7
Joined: 14.Feb.2006
Status: offline

I tend to think an IE issue as well. Here is the clip from the sniffer trace:

Hypertext Transfer Protocol
GET /wpad.da HTTP/1.1\r\n
   Request Method: GET
   Request URI: /wpad.da
   Request Version: HTTP/1.1
Accept: */*\r\n
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; win32)\r\n
Host: oints046.owens-ill.com\r\n
\r\n

Also I have copied my wpad.dat file on my IIS server and created a second file of just wpad.da. With this in place IE finds the second file with the truncated extension and the process completes using this file.

(in reply to ClintD)

Post #: 5

RE: WPAD issue - 14.Feb.2006 8:41:53 PM

spouseele

Posts: 12782
Joined: 1.Jun.2001
From: Belgium
Status: offline

Hi Dave,

are you using a Microsoft DHCP server?

I never saw that behavior but I've heard about it. As far as I can remember it has something to do with the way the DHCP option 252 is or should be encoded. If I look at my captures I see that the string is NULL terminated and that the length includes the NULL character.

HTH,
Stefaan

(in reply to zdgcook)

Post #: 6

RE: WPAD issue - 14.Feb.2006 9:07:16 PM

zdgcook

Posts: 7
Joined: 14.Feb.2006
Status: offline

Hello

It is not a Windows DHCP server. I am using VitalQIP version 6.0 SP1. Its on a Windows 2003 server, but is running the DNS and DHCP services from Lucent's VitalQIP. I did contact Lucent and upgraded to the latest version of their DHCP service with no change in the issue. I will try a configuration with the Windows DHCP server to see if that does the trick. Thanks for your input.

Dave

(in reply to spouseele)

Post #: 7

RE: WPAD issue - 14.Feb.2006 9:12:46 PM

spouseele

Posts: 12782
Joined: 1.Jun.2001
From: Belgium
Status: offline

Hi Dave,

aha... what happens if you just add an extra character to the string in the 252 option in the Lucent's VitalQIP DHCP service?

HTH,
Stefaan

(in reply to zdgcook)

Post #: 8

RE: WPAD issue - 14.Feb.2006 9:31:55 PM

zdgcook

Posts: 7
Joined: 14.Feb.2006
Status: offline

Adding an extra character in the QIP configuration results in the extra character being truncated at the browser and leaving us with the correct URL string. I have a limited number of workstation configurations to test with and was concerned that this approach might prevent other versions of the browser from connecting if they happened to received the full string. The environment that this will eventually serve has a mix of IE versions from 5.0 through 6. Is there a character that can be used that will be ignored if a browser gets the full string?

(in reply to spouseele)

Post #: 9

RE: WPAD issue - 14.Feb.2006 9:38:27 PM

spouseele

Posts: 12782
Joined: 1.Jun.2001
From: Belgium
Status: offline

Hi Dave,

yes, the NULL character (x'00').

HTH,
Stefaan

(in reply to zdgcook)

Post #: 10

RE: WPAD issue - 14.Feb.2006 10:43:11 PM

zdgcook

Posts: 7
Joined: 14.Feb.2006
Status: offline

That seems to correct the issue. To accomplish the null character, QIP's text parser required the entire URL to be entered as a quoted string with a space at the end. Thanks for all of your help.

Dave

(in reply to spouseele)

Post #: 11

RE: WPAD issue - 14.Feb.2006 10:56:28 PM