[vpn-help] DNS fails any time proxy is running even if not connected

Linwood Ferguson lferguson at thenewsgroup.com
Wed Jan 20 05:41:09 CST 2010


Problem: 
 
Suddenly I was unable to resolve names with DNS while NOT connected via VPN.   This occurred with no apparent change, after working for several weeks flawlessly.   So far the problem is only on a wireless connection.
 
Software version: 
 
Windows 7 64 bit (fully patched)
VPN client 2.1.5 release, and also 2.1.6 beta 3
 
Hardware: 
 
Dell E6500 laptop, clean Windows 7 install (Ultimate - legal) 
Current firmware, and both original and latest wifi card drivers tested
 
Scenario: 
 
WithOUT the VPN connection running, but with the "Shrewsoft DNS Proxy" service running, DNS requests fail.  A network trace shows no DNS request hits the network itself.  Stop the service - works fine.  Start again, fails.
 
I saw the TRAC report about VM issues, and resume from suspend.  This problem may be related but it does continue after a reboot without a suspend, and no VM is involved.   
 
I de-installed 2.1.5 and DNS worked fine afterwards (no service so that was expected).
 
I installed 2.1.6 beta three which I see may (eventually) address the bug report that seemed related - no change.  I tried enabing a log for debug from the DNS servce, but all I get is a banner and copyright.
 
This system was very stable with the software for serveral weeks (roughly from the 2.1.5 release which was the first installed on it).  I was travelling, it worked one day all day, the next day on first use it failed.  No software was installed (at least knowingly), no config changes made (again, at least knowingly).  It is now 100% failing (but equally 100% fixable by stopping the service).  
 
It is working on the wired NIC (though I cannot try the VPN connection itself as I do not have a wired nic outside of our company network at this location - only wireless internet).
 
I have tested it on two different wifi setups, unrelated (one my company, one a hotel), no change (and again, a sniffer shows no DNS packets being exchanged -- it is not getting off the laptop).
 
And with the service stopped, I cannot establish a VPN connection.
 
I repeated the de-install, wiped the main software registry, and re-installed -- even before importing any PCF files, DNS was failing, i.e. never once made an attempt at a VPN connection.
 
Any suggestions appreciated.
 
Below is a simple example of the failure from a command prompt.  VPN is not up during this, it was immediately after a fresh boot of the machine.
 
Below that is the only possibly relevant event log I see. However, this only appears on a STOP of the service.  It does not appear while running or during a START of the service, so I am not sure it is relevant.
 
 
Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.
C:\Windows\system32>nslookup google.com
DNS request timed out.
    timeout was 2 seconds.
Server:  UnKnown
Address:  10.10.84.1
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to UnKnown timed-out
C:\Windows\system32>net stop "Shrewsoft DNS Proxy Daemon"
.
The ShrewSoft DNS Proxy Daemon service was stopped successfully.

C:\Windows\system32>nslookup google.com
Server:  wireless.colubris.com
Address:  10.10.84.1
Non-authoritative answer:
Name:    google.com
Addresses:  74.125.95.105
          74.125.95.104
          74.125.95.106
          74.125.95.99
          74.125.95.147
          74.125.95.103
 
 
Faulting application name: dtpd.exe, version: 0.0.0.0, time stamp: 0x4b1aa514

Faulting module name: ntdll.dll, version: 6.1.7600.16385, time stamp: 0x4a5be02b

Exception code: 0xc0000374

Fault offset: 0x00000000000c6cd2

Faulting process id: 0x7b4

Faulting application start time: 0x01ca99c18c6b0c3b

Faulting application path: C:\Program Files\ShrewSoft\VPN Client\dtpd.exe

Faulting module path: C:\Windows\SYSTEM32\ntdll.dll

Report Id: ed0533f1-05b4-11df-8269-00242cb7bf08

 
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