Category: Windows

TeamViewer (sometimes) doesn’t work with DNSSEC enabled

Update (2022-12-06): It looks like TeamViewer fixed their DNS config (before and after).

Update (2022-11-12): I tested again after Frankie in the comments noted that it works on his machine, and indeed it does for me, too, even with DNSSEC turned back on. My only explanation is that it’s an intermittent issue.

I couldn’t figure out why TeamViewer was perpetually stuck in the ‘Not ready. Please check your connection’ state, and the help article didn’t give any clues (port 5938 was already open for outbound connections).

The dreaded ‘Not ready. Please check your connection’

The log files (/opt/teamviewer/logfiles/TeamViewer15_Logfile.log in Fedora) gave a hint:

The host would cycle from router1.teamviewer.com to router16.teamviewer.com, but none of them would resolve. Long story short, DNSSEC is broken for these TeamViewer domains, and the application won’t work if none of them can be reached.

Sadly, this problem was reported years ago but nothing has changed.

Workarounds

Neither of these is good! I recommend contacting TeamViewer and letting them know about this issue (particularly if you’re a paying customer).

Hard code an IP address in hosts

Adding an IP address for router1.teamviewer.com to hosts seems to make the application functional.

I just picked the first IPv4 address and added it to /etc/hosts:

These IP addresses are of course liable to change.

Disable DNSSEC

Note: DNSSEC exists for a reason – don’t disable it unless absolutely necessary.

The nuclear option is to turn off DNSSEC checks entirely, or switch to using DNS servers that don’t support it in the first place (I recommend neither).

On Fedora 36 with systemd-resolved, this means editing /etc/systemd/resolved.conf and adding DNSSEC=no under [Resolve].

Beware of the MiniNT registry key

As of Windows 10 Version 1511, ReFS isn’t available by default as an option when formatting drives that aren’t part of a Storage Space. It’s easy, however, to enable this functionality by adding a DWORD named AllowRefsFormatOverNonmirrorVolume under the Registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MiniNT (an example guide can be found here).
Unfortunately, the presence of MiniNT Registry key causes various Windows components to think they’re running in the Windows Preinstallation Environment. Significantly, the presence of the key breaks the Event Viewer – attempt to open any log and you’ll be greeted with the following very unhelpful error message:

Event Viewer cannot open the event log or custom view. Verify that Event Log service is running or query is too long. The request is not supported (50)

If this weren’t enough, apparently Windows PowerShell remoting will stop working, too.
TL;DR: Delete HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MiniNT as soon as you’re done formatting your drive with ReFS.

I bet somebody got a really nice bonus for that feature: The 'Get Windows 10' notification area icon

As the great Raymond Chen once wrote:

I often find myself saying, “I bet somebody got a really nice bonus for that feature.”

“That feature” is something aggressively user-hostile, like forcing a shortcut into the Quick Launch bar or the Favorites menu, like automatically turning on a taskbar toolbar, like adding an icon to the notification area that conveys no useful information but merely adds to the clutter, or (my favorite) like adding an extra item to the desktop context menu that takes several seconds to initialize and gives the user the ability to change some obscure feature of their video card.

The ‘Get Windows 10’ application that Microsoft deployed to Windows 7 and 8.1 machines earlier this year as a recommended – not even optional – update (KB3035583) sure fits this bill.

In short, every eligible Windows 7 and Windows 8.1 user ends up with this icon in their notification area: Get Windows 10 Icon

Apart from looking fairly ugly (that top edge in particular is a blurry mess), there’s no way to close it even temporarily, short of killing GWX.exe in the Task Manager – note also that no-one thought to give it a descriptive name; it’s just ‘GWX’.

I understand Microsoft’s desire to have users promptly upgrade to Windows 10 (even if I wish they would delay its release by a year or so), but this kind of approach just destroys goodwill.

Fixing error 0xC190010C when attempting to update the Windows 10 Technical Preview

My Hyper-V virtual machine running the Windows 10 Technical Preview kept displaying the error code 0xC190010C when I attempted to update to the latest build (from 9841 to 9860).

I was able to resolve this issue by clearing the Windows Update cache as described here. Briefly:

net stop wuauserv
rmdir /s %WinDir%\SoftwareDistribution
net start wuauserv

Enabling the compatibility property sheet for (almost) all programs in Windows 8/8.1

Windows 8 and 8.1 hide the compatibility property sheet for certain programs (namely programs included with Windows, like Notepad, and those on a whitelist of programs known to run correctly on Windows 8/8.1 – defined in %WinDir%apppatchpcamain.sdb). In some cases, one can still run the ‘troubleshoot compatibility’ wizard by right-clicking on the file, which just presents compatibility settings in a novice-friendly, poweruser-unfriendly way.

The compatibility property sheet and context menu are defined in acppage.dll. By patching this DLL, we can enable the compatibility property sheet for (almost) all programs, including programs like Notepad and those whitelisted in pcamain.sdb.

Patching Windows system DLL files is probably a bad idea, and I take no responsibility if your computer explodes after you take the following steps.

I’ll write a tool to automate this process at some point, but for now, here are the manual steps if you’re feeling adventurous:

  1. Make a backup of acppage.dll from %WinDir%System32
  2. Take ownership of acppage.dll in %WinDir%System32:
  3. Grant administrator users full control over acppage.dll:
  4. Using your favourite hex editor (I like XVI32), overwrite the two bytes at the relevant address to 0x31 0xC0:

    • Windows 8.1 64-bit: 5A92 (the original bytes should be 0x8B 0xC7)
    • Windows 8.1 32-bit: 4B26 (the original bytes should be 0x8B 0xC6)
    • Windows 8 64-bit: 4DBB (the original bytes should be 0x8B 0xC3)
    • Windows 8 32-bit: 3D44 (the original bytes should be 0x8B 0xC6)

    Warning: If the existing bytes don’t match with what I’ve written above, don’t overwrite them! The addresses change with patches to Windows. The above addresses were current as of 2013-09-04.

  5. Restart explorer.exe

Voilà – the compatibility property sheet will appear for most programs now (I’ve noticed that it doesn’t show up for File Explorer):

Screenshot of Notepad.exe and the Compatibility property sheet

How does this actually work?

These two bytes are in the CLayerUIPropPage::Initialize function – this basically does a bunch of checks to determine whether the property sheet should be displayed or not. The original code (0x8B …) sets the return value (the EAX register) to the result of these checks – a non-zero result means the sheet won’t be displayed. We modify the function to always return 0 by using the instruction xor eax, eax (0x31 0xC0).

Windows 8.1 Impressions

Windows 8.1 is done, though Microsoft is apparently worried enough about driver and application support that not even loyal MSDN and TechNet subscribers will get it until October 17 this year. To no-one’s surprise, the RTM ISOs were promptly leaked, which leaves us in the odd situation where the only way to test your programs against the latest version of Windows is to download disc images from shady websites.

My impressions of Windows 8.1 don’t differ much from what I wrote earlier this year when it was still ‘Windows Blue’: no-one who hates Windows 8 is going to be swayed by Windows 8.1, but if you love Windows 8, you’ll probably love Windows 8.1.

For all that’s been written about the return of the Start Button, there are very few concessions towards desktop users in Windows 8.1. Including ‘boot to desktop’ and ‘use desktop background on Start Screen’ as options makes the overall user experience slightly less jarring, but it’s really nothing to get excited about. I highly recommend StartIsBack to restore the Windows Vista/7-style Start Menu. Start Menu programs abound (what does that tell you?), but StartIsBack really feels like it’s part of Windows, not a third-party program.

The biggest change that Windows 8.1 brings to the desktop is improved high DPI support – Windows now supports per-monitor DPI, and no longer requires users to log off in order to change their DPI settings. I’m sceptical about how many applications will bother supporting this functionality, but it’s a nice feature to have.

Given that Windows 8.1 doesn’t offer much to desktop users like me, I might as well write about annoyances introduced with this version.

New annoyances

  • Microsoft has made it hard to create a local account when installing Windows (as opposed to using a Microsoft account to sign in). Windows 8 strongly encouraged you to use a Microsoft account, but Windows 8.1 is worse – the only methods I’ve found to avoid this are to disable network connections or to type in a bogus email address – only then will Windows offer to create a local user account.
  • SkyDrive is now integrated with Windows, but apparently only if you sign in with a Microsoft account (see above). I guess I won’t be using the desktop SkyDrive client anymore.
  • Libraries are hidden by default, and even when they’re turned on, the navigation pane in File Explorer is polluted with shortcuts to the ‘Desktop’, ‘Documents’, ‘Downloads’, ‘Music’, ‘Pictures’ and ‘Videos’ folders (not libraries), as is the main ‘This PC’ (formerly ‘Computer’ – who decided changing that was a good idea?).
  • Unlike some, I don’t hate the default background images (though I question the choice of the orange default image), but the JPEG compression is horrendous. I’m shocked that Microsoft included such low-quality images in Windows.

None of these are show-stoppers, but coupled with the fact that Windows 8.1 offers almost nothing new for desktop users, it’s hard to get excited about this update.

Warning: Simple Storage Spaces in Windows 8 can’t be dismantled

A new feature in Windows 8 is ‘storage spaces’, a kind of software RAID, similar to the drive extender functionality found in the defunct Windows Home Server. Unlike Windows Home Server, however, Windows 8 provides no means of removing hard drives from simple (no resiliency) storage spaces, even when there’s adequate free space. Deleting the storage space will remove all your data, so you’ll need to copy everything to other storage devices first. If all your hard drives are being used by the storage space, this can be tricky.

My home server has recently decided to reset itself at random intervals (no errors to speak of), possibly due to an incompatibility between some piece of hardware and Windows 8 (or possibly just a failing piece of hardware). I’d like to try re-installing Windows 8 to see if that helps, and try Windows 7 if it doesn’t, but first I need to find a way to transfer about 8TB of data from my storage space.

Moral of the story: don’t use simple storage spaces if you ever plan to dismantle them.

Theme Colours in Windows ‘Blue’

As I noted in my earlier post, the method for selecting theme (‘accent’) colours in Windows ‘Blue’ build 9364 has changed from Windows 8 RTM. I’m not going to bother looking too closely at the updates to the functions in UxTheme.dll this early in the development process, but I did notice two new registry values in the key HKCUSoftwareMicrosoftWindowsCurrentVersionExplorerAccent: ‘AccentColor’ and ‘StartColor’. These are DWORD values that store the accent colour and background colour, respectively. The format is 0xAABBGGRR. The old ‘ColorSet_Version3’ value from Windows 8 is gone for obvious reasons. ‘AccentId_v8.00’ from Windows 8 is now ‘MotionAccentId_v1.00’, but it seems to serve the same purpose – indicating which background image is selected.

Native Tooltips in WPF (Part 2)

View source on GitHub.

In part 1 of this article I looked at the differences between WPF tooltips and ‘native’ (Win32) tooltips. In this part I present a sample WPF application that displays native tooltips. I’d planned to walk through some of the code here, but that turned out to be a bit tedious, so you’ll have to make do with the comments in the sample.

NativeToolTip.7z
11,271 bytes; SHA-1: 4ABD39CE46F5386E6D2DFF4A788AC3231DFA8765

Limitations:

  • ToolTipService.Placement must be set to ‘Mouse’ (the default). Custom positioning is not available. (You could implement it with a tracking tooltip, but that’s easier said than done.)
  • Native tooltip content is limited to simple strings.

Remarks:

  • TTM_POPUP doesn’t work if the ‘rect’ field of the TOOLINFO isn’t set. This had me stumped for a while.