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Some clients don't get wpad.dat file

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Some clients don't get wpad.dat file - 13.Feb.2007 9:00:15 AM   
Nik007

 

Posts: 23
Joined: 25.Aug.2006
From: Belgium
Status: offline
Setup: ISA Server2004 Edge firewall SP2 (just went live with the following problem). We use Web Proxy clients via wpad.dat provided by DHCP (windows 2003).

Problem: On some clients the wpad.dat file is not downloaded and they are not able to surf. I have this on XP SP2 and W2K SP4 clients.  Users are administrator of their PC.  As test I've put them also in the New. Config. Op. group but  still the same problem.

 
A work-around is to clear the "Automatically detect settings" check box in IE and to check it again (strange?).
 
Because I need a "real"-solution in our live envirnment I've checked the following doc http://www.microsoft.com/technet/isa/2004/ts_wpad.mspx section "Latest wpad.dat Information Is Not Being Applied"
 
The command "Autoproxutil /f:3" seems to solve this but where can I find this command tool? 

Are there other solutions to solve this because e.g. I'm not able to apply a logon scritp for visitors.

 
Thx

< Message edited by Nik007 -- 14.Feb.2007 4:24:01 AM >
Post #: 1
RE: Some clients don't get wpad.dat file - 17.Feb.2007 5:08:21 AM   
spouseele

 

Posts: 12830
Joined: 1.Jun.2001
From: Belgium
Status: offline
Hi Nik007,

check out the following links:
- Understanding the Web Proxy and Firewall Client Automatic Configuration
- Jan 13th, 2006 - Update to Understanding the Web Proxy and Firewall Client Automatic Configuration article
- Feb 13th, 2006 - Update to Understanding the Web Proxy and Firewall Client Automatic Configuration article

HTH,
Stefaan

(in reply to Nik007)
Post #: 2
RE: Some clients don't get wpad.dat file - 20.Feb.2007 10:06:31 AM   
Nik007

 

Posts: 23
Joined: 25.Aug.2006
From: Belgium
Status: offline
Stefaan,
 
The docs you mention describe a delay problem. For me it's not a delay problem.  After the ISA was implemented, on most clients, the first time they tried to access the Internet it failed (isa denied access).  I have a rule based on user authentication to access the Internet.
 
After investigation I found out that the client clients don't receive the wpad.dat at all.  A quick solution is to clear the "Automatically detect settings" check box in IE and to check it again it (strange) and they receive the wpad.dat file and are able to surf.  This setting is applied by a gpo.  After this everything is ok for a client even after a restart.
 
The command "Autoproxutil /f:3" seems to solve this, do you have this command tool, see http://www.microsoft.com/technet/isa/2004/ts_wpad.mspx  instead of clearing the setting and re-enabling it manually the first time
 
Are there other solutions to solve this because e.g. I'm not able to apply a logon scritp for visitors.
 
Thx already for the feedback.
 
 
 

< Message edited by Nik007 -- 20.Feb.2007 10:26:12 AM >

(in reply to spouseele)
Post #: 3
RE: Some clients don't get wpad.dat file - 20.Feb.2007 3:38:03 PM   
spouseele

 

Posts: 12830
Joined: 1.Jun.2001
From: Belgium
Status: offline
Hi Nik007,

quote:

The docs you mention describe a delay problem.

Not entirely true. That article explains in depth how the automatic configuration stuff really works. The updates to the article are indeed about the DHCP delay problem seen.

I never have to apply a GPO or whatsoever to get automatic configuration working with IE. Just use the default IE settings and it works!

HTH,
Stefaan

(in reply to Nik007)
Post #: 4
RE: Some clients don't get wpad.dat file - 21.Feb.2007 5:19:08 AM   
Nik007

 

Posts: 23
Joined: 25.Aug.2006
From: Belgium
Status: offline
Stefaan,

Sorry to come back on the subject but it creates some work-load (calls) for our helpdesk.  Imagine you have about 1000 clients.

Even if it's a default setting (autonatically detect settings checked),
I need to make sure that this settings is checked because it could be un-checked for wathever reason. Else users are not able to access the Internet, call the helpdesk, ...

In one of our GPO I configure user settings - windows settings - ie maintenance - connection - automatic browser config - checked automatic detect config settings.

A client which has this problem has this setting checked, so normally it should work.  Strange enough when I than clear the setting and check it again it works.  Also after a restart the problem is gone. 

Do you know where I can find the "Autoproxutil"command tool?

Other workaround I've read in the document is to delete the following HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections registry key entries:
- DefaultConnectionSettings. This entry specifies the configuration of the default connection used by Internet Explorer.
- SavedLegacySettings. This entry is a copy of DefaultconnectionSettings, and specifies the configuration used by network connections other than the default connection.

When Internet Explorer is launched and gets the Wpad.dat file, it flags the value DefaultconnectionSettings at the offset 59 with the value 05. This offset is designed to indicate that Internet Explorer should send a DHCP Inform to get the Wpad.dat file, and changes the offset 59 of the value DefaultConnectionSettings to 05. To force Internet Explorer to get the new URL to the Wpad.dat file, the offset 59 should be set to 01. The Autoproxutil tool is used to do this. To run the Autoproxutil tool, execute the command:
Autoproxutil /f:3

This command forces Internet Explorer to send a DHCP Inform the next time it is launched.

Other workarounds:
Clear or select the Automatically detect settings option.
Execute the Autoproxutil tools in a logon script.
Delete the DefaultConnectionSettings and SavedLegacySettings registry keys.

< Message edited by Nik007 -- 21.Feb.2007 5:43:44 AM >

(in reply to spouseele)
Post #: 5
RE: Some clients don't get wpad.dat file - 21.Feb.2007 2:27:23 PM   
spouseele

 

Posts: 12830
Joined: 1.Jun.2001
From: Belgium
Status: offline
Hi Nik007,

what happens if you use the DNS method for wpad instead of the DHCP method?

HTH,
Stefaan

(in reply to Nik007)
Post #: 6
RE: Some clients don't get wpad.dat file - 16.Mar.2007 9:30:07 AM   
Nik007

 

Posts: 23
Joined: 25.Aug.2006
From: Belgium
Status: offline
Stefaan,

I'm not able to test this in our live-environment.  We are WW (we=EMEA, US, ASIA) connected by a private network and have 1 domain e.g. abc.com.  If I configure it via the DNS method, users in other offices e.g. US will get the wrong gateway and are going via our Internet connection in EMEA (Belgium).  That's is the reason why I configured it via dhcp.  Besides the ww private network has every office his own Internet access.  In our case protected by ISA.

Nik

(in reply to spouseele)
Post #: 7
RE: Some clients don't get wpad.dat file - 16.Mar.2007 5:57:12 PM   
spouseele

 

Posts: 12830
Joined: 1.Jun.2001
From: Belgium
Status: offline
Hi Nik007,

any chance you can provide us a NetMon trace of a good and bad wpad DHCP session.

HTH,
Stefaan

(in reply to Nik007)
Post #: 8

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