The default DNS after connecting (the one that NSLOOKUP identifies) is a
server on the client network's in the client's AD domain, which has a
completely different set of authentication credentials - different from my
local domain, and different from the VPN gateway.

 

Just to re-cap...

 

1. I authenticate to my local domain first on logging into Windows.

2. Then I authenticate to the remote VPN gateway server via the VPN
connection.

3. Then I authenticate to the remote Windows servers by supplying a 3rd set
of credentials on the NET USE command line.

 

If anything, I'd expect that the more recent credentials - from item (3) -
would be attempted for re-authentication to my local domain.   But no, it's
the ones from the VPN connection (2), that get tried.

 

So I'm highly doubtful of a DNS issue, but there's one scenario I haven't
tried in attempt to prove it, and that would be to map a drive using the
local server's IP address and see if that also goes away when the ones
mapped by name go away.  I will give that a try ASAP...

 

Carl

 

From: John Gwinner [mailto:[EMAIL PROTECTED] 
Sent: Wednesday, December 10, 2008 3:57 PM
To: NT System Admin Issues
Subject: RE: Lose access to local domain servers when connected w/VPN to
remote / different Windows domain

 

Is it a default gateway issue?  ISA 2004 can force you to use the default
gateway on the remote side.

 

Also, is it a DNS issue?  When you connect to a VPN, even one that forces
default gateway behavior, the DNS order might be wrong.  Apparently it's a
50/50 issue which DNS server will reply first.

 

I have this problem on my own side, my internal servers have 'corp.com' DNS
settings that resolve to 192.168.x.x. numbers, but when you connect to the
VPN, you get a 66.150.x.x number - outside the firewall, even though you are
on the VPN.  If this is the problem, maybe your DNS gets confused and your
local DC suddenly gets reached via a public IP, which is blocked.

 

I assume the subnets are separate, i.e. you aren't both using 192.168.0.X.

 

           == John ==
 

From: Carl Houseman [mailto:[EMAIL PROTECTED] 
Sent: Wednesday, December 10, 2008 12:30 PM
To: NT System Admin Issues
Subject: RE: Lose access to local domain servers when connected w/VPN to
remote / different Windows domain

 

No, the usernames and passwords are different, and they must remain that
way.

 

Carl

 

From: Steve Ens [mailto:[EMAIL PROTECTED] 
Sent: Wednesday, December 10, 2008 2:35 PM
To: NT System Admin Issues
Subject: Re: Lose access to local domain servers when connected w/VPN to
remote / different Windows domain

 

You do have a local account on the remote server....same username and
password I presume?

On Wed, Dec 10, 2008 at 1:28 PM, Carl Houseman <[EMAIL PROTECTED]> wrote:

This problem has bothered me a long time, and happens daily.  It's so
bothersome, I'll send some Dale & Thomas popcorn to the first person who can
come up with a solution or a tip that quickly (without many hours of effort
on my part) leads to a solution.  Advice such as "call Microsoft" does not
qualify for the popcorn!

 

Past history:  The problem was seen for Windows XP but seems to be worse
under Vista.  In fact I wrote about it in reference to XP to this list a
year or two ago without any resolution.  Certainly what I'm doing here can't
be that unique, aside from relying on Microsoft-based VPN solutions...
(kindly withhold comments on the worthiness of those solutions).

 

Goes like this:

 

In my local office, there are two 2003 servers - member and domain
controller.  My everyday Vista SP1 is joined to that domain.  I have drives
mapped to both servers.

 

I use an L2TP/IPSEC VPN connection to connect to a client's network.   The
client's VPN gateway is ISA 2006, joined to the client's Windows domain, but
I authenticate for the purpose of the VPN connection using a local username
on the ISA server.  We'll call the ISA server "ISAVPN" in further
discussion.

 

What happens:  Sooner or later I will be unable to access the drives mapped
to my local domain's servers (UNC references to those servers also fail).
The error returned when just trying to do anything at the CMD prompt
defaulted to a mapped drive on either server is:

 

Logon failure: unknown user name or bad password.

 

Once I disconnect from ISAVPN, at the very same CMD prompt, I again and
immediately have access to files on my local servers.

 

This seems to affect access to the member server a short time after
connecting to ISAVPN.  Access to files on the domain controller usually
keeps working much longer, but eventually I lose it as well.  This behavior
has guaranteed repeatability 100% of the time.

 

I should note that the domain controller's mapped drive is "available
offline" but Vista does not switch to offline because of this problem. 

 

Looking in the security event log of the server, I see events 529 and 680
(source Security), in pairs, related to the login failure, with the 529
having the most information:

 

Logon Failure:

            Reason:            Unknown user name or bad password

            User Name:       local_username_on_ISAVPN

            Domain:            ISAVPN

            Logon Type:     3

            Logon Process: NtLmSsp 

            Authentication Package:            NTLM

            Workstation Name:                    MYVISTAPC

 

My take on it:  At some point, SMB access has to re-authenticate and is
using the more recent credentials from the VPN connection to talk to my
local servers.  I'm guessing binding order somewhere is the problem, but
where can I find and fix this binding order?  A permanent one-time solution
would be nice, but it's OK if I have to fix it every time after making the
VPN connection.

 

thanks all,

Carl

 

 

 

 

 

 

 

 

 

 

 

 

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