Month: September 2016

WinPE manage-bde –protectors –disable C: unexpectedly enables encryption

Final update – my BIOS configuration script had a command to temporarily disable BitLocker in case configuration was applied from already deployed OS. Good old manage-bde –protectors –disable C:

However this command unexpectedly applied BitLocker to FAT32 boot volume. When querying status with manage-bde -status there is no encryption. However volume is actually encrypted. Booting to WinPE on next start would clear encryption so it only showed up when using Linux live media. Duh!

Why would it do that? Don’t know. In the end HP BIOS boots just fine and does not require ESP partition. I edited title to reflect on the actual issue.

Hold your horses! All information below is irrelevant as HP desktop BIOS seems to have a bug. It will not properly enumerate UEFI boot drives after mode switch. It may boot sometimes but not consistently. Currently only workaround is to boot to PXE after mode switch and restart TS.

So I was looking at this great guide on conversion from BIOS to UEFI boot in SCCM TS.

However my BIOS/UEFI configuration is more locked down and HP professional desktops flat out refuse to boot from plain FAT32 partitions with some options set. I’m guessing it’s because of Removable Media Boot: Disable. But still I needed to work around that. After some tinkering I discovered that boot worked fine if partition was set as EFI boot partition. However this caused WinPE to not mount it at boot. No mount, no task sequence data, fail.

So I created 2 partitions, first for EFI boot, second for WinPE. Then I configured BCD to point to second partition and set first as EFI boot partition. Boom, it works!

Notes:

  • As always, could be more efficient but good enough…
  • My configuration is a bit different. I have both x86 and amd64 WinPE data in one package (in subfolders) to support both 32bit and 64bit UEFI implementations in one package and I select relevant boot set with %PROCESSOR_ARCHITECTURE% variable. Package download size is bigger but that’s not an issue for me. This also implies that PXE WinPE image must be the same as target architecture.
  • In “Format and Partition Disk” step create 2 Primary partitions. First must be smaller than the second one (for example 2GB and 4GB). This is necessary as TS data is stored on the larger partition and EFI partition will not be mounted on next boot. Set first partition variable to EfiDrive and second to BootDrive
  • Call WinPE deployment script as 
    


    copy.cmd %EfiDrive% %BootDrive%

Modified copy.cmd




@ECHO OFF
set efidrive=%1
::S:
set bootdrive=%2
::C:
XCOPY %~dp0%PROCESSOR_ARCHITECTURE%\* /s /e /h %bootdrive%\

::https://technet.microsoft.com/en-us/library/hh265131%28v=ws.10%29.aspx

xcopy %bootdrive%\EFI\* %efidrive%\EFI\* /cherkyfs
copy %bootdrive%\windows\boot\EFI\*.efi %efidrive%\EFI\Microsoft\Boot\*
del %efidrive%\EFI\Microsoft\Boot\BCD /f

bcdedit -createstore %efidrive%\EFI\Microsoft\Boot\BCD

bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -create {bootmgr} /d "Boot Manager"
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -create {globalsettings} /d "globalsettings"
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -create {dbgsettings} /d "debugsettings"
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -create {ramdiskoptions} /d "ramdiskoptions"
for /f "Tokens=3" %%A in ('bcdedit /store %efidrive%\EFI\Microsoft\Boot\BCD /create /application osloader') do set PEStoreGuid=%%A

bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD /default %PEStoreGuid%

bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {bootmgr} device partition=%efidrive%
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {bootmgr} path \EFI\Microsoft\Boot\bootmgfw.efi
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {bootmgr} locale en-us
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {bootmgr} timeout 10

bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {Default} device ramdisk=[%bootdrive%]\sources\boot.wim,{ramdiskoptions}
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {Default} path \windows\system32\winload.efi
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {Default} osdevice ramdisk=[%bootdrive%]\sources\boot.wim,{ramdiskoptions} 
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {Default} systemroot \windows
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {Default} winpe yes
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {Default} nx optin
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -set {Default} detecthal yes
bcdedit -store %efidrive%\EFI\Microsoft\Boot\BCD -displayorder {Default} -addfirst

diskpart /s "%~dp0diskpartefiboot.txt"




diskpartefiboot.txt





select disk 0
select partition 1
set id=c12a7328-f81f-11d2-ba4b-00a0c93ec93b




Voilà! It boots!


…occasionally on some systems fastfat driver doesn’t load. It’s load type is 3 – manual (ondemand). Partitions are shown as RAW and TS will fail as data cannot be loaded. Investigating.

Deduplication, offline files and Microsoft Office don’t mix

There’s a bug in the way that dedup, offline files (Client Side Cache – CSC) and Microsoft Office interact. My guess is that problem relies in CSC but lets get into details.

Scenario:

  • SMB share stored on deduplicated volume on WS2012R2 (2012R1 probably as well) server
  • Windows 7 or Windows 8.1 client (not tested on Windows 10)
  • Share or files on share are set as available offline
  • Client stores a 32kB+ Office file (doc, docx etc…) on share
  • File gets deduplicated and obtains reparse point (important) attribute
  • Changed attributes get synced to client
  • Client is working offline (disconnected or with always offline policy)
  • Client attempts to save changes to file in Microsoft Office

Boom, error! Gotcha! Why is this a problem? Let’s go over details.

  • CSC downloads actual files contents from server and stores them in flat files without metadata.
  • ACLs and attributes get stored in some separate database. I haven’t bothered to go deeper but flat files don’t have relevant ACLs nor attributes in actual backing file system. Maybe extended attributes or ADS…? I’ve never noticed anything similar to a “CSC.db”.
  • CSC presents files with relevant attributes to applications. Eg ACLs (mostly, not going into details) work and serverside attributes get presented to applications, including hidden read-only file system specific ones.
  • Microsoft Office is being smart and trying to enumerate reparse point data (probably for cases such as https://blogs.msdn.microsoft.com/oldnewthing/20051128-10/?p=33193). Remember we’re working offline.

Now things go wrong

  • Querying reparse information fails because…
  • CSC only masks reparse point attribute on stack without actual metadata.
  • Data on backing disk files is not actually a reparse point.
  • Client does not have dedup filter driver anyways.
  • Boom, query fail, no saving for you today.

Most other applications (in fact MSO is the only case I’ve found) just don’t care about reparse point and write to file just fine. For example Notepad doesn’t check attributes and just works. In my case, I was using always offline policy for folder redirection (online performance is awful on slow links) and it destroyed user productivity as users had to always save changes into new files.

It took me about a year to get through Microsoft support and get this issue confirmed. A hotfix was promised after April 2016 but so far it doesn’t seem to have been fixed.

Workaround is to exclude all and any file types from deduplication that you expect Microsoft Office users to modify and then rehydrate all those files server-side. If you have tons of these, your storage requirements will blow up, especially if you’ve come to depend on dedup. But end-users are happy and don’t constantly have to save edited data into new files.

Outlook Auto-Mapping and delegation to groups

As discussed here, Outlook doesn’t auto-load delegated mailbox if delegation target is a group.

In the backend, Exchange populates msExchDelegateListLink attribute for for delegated mailbox user that is linked to delegated users based on DN. However, it is not populated for groups as Exchange is not directly aware of group membership changes. As a workaround, you can do it yourself as a scheduled job. Here’s a script for that.

Notes:

  • It adds group member DNs msExchDelegateListLink to attribute and also cleans up removed members (both direct and group members)
  • Logging and internal comments have been removed
  • Script is quite expensive (resource-time wise), in my environment it takes 2-3 minutes to run.
  • I have scheduled it to run every 2-3 hours, adjust to your requirements.
    Outlook should pick up changes in a few minutes after run.
  • Run visible mailbox size checker first so you don’t blow user’s default 50GB OST limit.
  • I’m running Exchange 2016 but 2010 SP1 and up should work.
  • This script will directly write to your AD, understand and test script first, understand the risks.
  • You need to load Exchange PowerShell snap-in or remote management sessioon first.
Function Populate-msExchDelegateListLink {
	$MailboxList = get-Mailbox -ResultSize Unlimited
	ForEach ($Mailbox in $MailboxList) {
		$mailboxpermissions = get-mailboxpermission -identity $mailbox.name | where isinherited -EQ $false | where accessrights -EQ 'FullAccess'
		$UserMembers = @()
		$GroupMembers = @()
		ForEach ($MailboxPermission in $mailboxpermissions) {
			$NormalizedName = $mailboxpermission.user.ToString().split('\')[1]
			#This is dumb but... it works!
			$CheckIfGroup = $(Try {Get-AdGroup -Identity $NormalizedName} Catch {$null})
			$CheckIfUser = $(Try {Get-Aduser -Identity $NormalizedName} Catch {$null})
			If ($CheckIfGroup) {
				$GroupMembers += $CheckIfGroup.DistinguishedName
			} ElseIf ($CheckIfUser) {
				$UserMembers += $CheckIfUser.DistinguishedName
			}
		}
		Foreach ($GroupMember in $GroupMembers) {
			$GroupMemberShip = (Get-ADGroupMember -Identity $GroupMember -Recursive | Where-Object 'ObjectClass' -EQ 'user' | Where-Object 'DistinguishedName' -NE $mailbox.DistinguishedName).DistinguishedName
			$GroupMemberShip | % {$Usermembers += $_}
		}
		$MailboxDelegateList = (Get-ADUser -Identity $Mailbox.DistinguishedName -Properties msExchDelegateListLink).msExchDelegateListLink
		ForEach ($MailboxDelegateListEntry in $MailboxDelegateList) {
			If ($UserMembers -notcontains $MailboxDelegateListEntry) {
				Set-ADUser -Identity $Mailbox.DistinguishedName -Remove @{msExchDelegateListLink="$MailboxDelegateListEntry"}
			}
		}
		ForEach ($UserMember in $UserMembers) {
			If ($MailboxDelegateList -notcontains $UserMember) {
				Set-ADUser -Identity $Mailbox.DistinguishedName -Add @{msExchDelegateListLink="$UserMember"}
			}
		}
	}
}

Porting System Center Operations Manager Management Pack to Zabbix

Figuring out performance counter discovery inspired me to investigate possibility of porting SCOM MP to Zabbix. I’ve spent a few days playing with the idea and Windows Server MP and I think that fairly similar experience can be achieved. My objectives:

  • Minimal configuration on the target server – only allow server commands and increase command timeout.
  • Minimal dependencies on target server – PowerShell only
  • No scripts must be deployed on target server
  • Multi-instance items are auto-discovered
  • Functionally similar alerts and gathered data

After few days of tinkering, there have to be compromises:

  • 255 character key limit implies a lot of compromises
  • Some counters have to be changed because of that (Processor vs Processor Information)
  • SCOM MP has some huge scripts with extended error checking and data collection that cannot be fully re-implemented due to key limitations
  • Due to that there will be compatibility and support issues
  • Scripts use different interfaces based on operating system version and edition (full or core) to work around bugs and issues. This cannot be faithfully emulated. Workarounds might be version-edition based templates or flipping discoveries on-off manually. I don’t think you can automatically flip discoveries based on other queries.
  • Edge cases might be missed naturally
  • Pretty much everything requires custom LLD script as agent discovery is useless
  • Item prototypes across discoveries have to be unique even though generated items are guaranteed to be unique. This again runs into problems with key length on some objects.
  • Some items have to be discovered multiple times due to subtle differences between interfaces. For example Network Adapter performance counters and MSFT_NetAdapter have different interface names due to some characters not being supported in perfmon (various brackets are changed, # gets changed to _). Another example is LogicalDisk perfmon that uses disk letter (where possible) or object manager name (for example boot volume). However volume metadata cannot be queried using object manager name so you must rediscover volume GUIDs.
  • Unit monitors and rules might use the same counters but Zabbix doesn’t allow duplicate items/keys. So far the best solution is to use “perf_counter[counter]” for unit monitors/triggers and averaged “perf_counter[counter,interval]” for rules. There might be fewer alerts as measurements are short but at least historical data collection is more accurate. It’s really one or the other way…
  • Many triggers need anti-flap measures as Zabbix has no global solution for that.
  • Key limit means that realistically only one macro or data value (or two in some cases) can be collected per LLD or item. Some metadata is lost, especially in Event Logs.
  • Event Log based rules may have to be split over multiple items as XPath queries are fairly long. They can be gathered under single trigger though.
  • I haven’t decided whether to go for discovery based Event Log processing or simple item based. Discovery based means that multiple items-triggers-alerts could be generated for distinct events, however I’m concerned that I’ll hit key length limitations and this would be abusing LLD functionality. Simple item based however is much simpler but you only get indication that something is wrong that requires more investigation.
  • As maximum agent timeout is 30 seconds, some long checks are likely to time out, such as defrag analyze or readonly chkdsk.

I’m halfway done so I guess I’ll publish on GitHub or something when I have something useful. Some community cooperation would be nice for some cases. Some analysis/compromises might change as I find workarounds to problems.

Update 6.9.2016

Monitors and rules are pretty much all implemented. I’m still polishing the scripts to put as much logic as possible in LLD keys but I’ve worked around some issues. I guess I’ve also spotted some bugs in MP. Current notes list:

  • It turns out that I’m an idiot and some LLD discoveries do work out better with ConvertTo-JSON. I can avoid expensive double quotes this way (expensive as 1 double quote results in 6 characters in final LLD key string if square brackets are also involved), allowing more logic and more item macros to be returned if necessary. This implies PS/WMF 3.0 but I think that’s a reasonable compromise.
  • Some LLD queries get “Not supported” error on some servers for no apparent reason, must debug.
  • I’m working on applications. So far it’s a mess but I guess I’ll stick to 3 applications (Collection, Alert, Monitor) per category (Logical Disk, Operating System…)
  • I haven’t touched views to graphs much but some issues:
    • You can’t create horizontal graphs (for example add counter X for each LLD discovered item X to one graph) for LLD items without ugly server-side scripted workarounds.
    • As some views reference items that I’ve discovered under different LLD queries. No reasonable way to add them to single graph.
  • No overrides for most items for most triggers. I did a few for items that regularly hit thresholds in my environment but macros are really uncomfortable to use so I skipped over that.
  • Event Log based items check for events in last 24 hours. Anything more would take forever for alerts to clear. It’s quite simple to implement and works reasonably well.
  • Some Event Log rules in MP specify plain wrong event sources (eg quota events are from NTFS, not Disk). Some sources have different names but I can’t test them all as I have no samples.
  • Most event log rules can’t be tested as I have no samples to collect.
  • Checks are not consistent. Some return number of events, some full message from last event, some an attribute from last event. It depends on how I thought it’d work best.
  • I’ve added a few extra checks that MP itself doesn’t cover. For example
    • Agent ping to detect downtime.
    • .NET assemblies get updated (ngen update) daily as some scripts require libraries to be up-to-date and compiled for maximum performance to fit in timeout window.
    • Defrag analyze gets invoked daily. It surprisingly mostly fits gets done in 30 seconds, unless volume is really badly fragmented. VSS dedicated volumes trigger an alert (I guess you can’t defrag VSS snapshot data)without reasonable way to automatically exclude but you can always disable problematic trigger on host.
    • ChkDsk and Defrag (if over threshold, regardless of previous analyze result) get invoked daily as maximum update interval is 24 hours. So far it seems to work well. Items report errors because of timeout but as WMI keeps running on client, jobs actually complete. I’m not sure if ChkDsk sets dirty flag if read-only ChkDsk finds issues but I hope it does so another item can detect an issue.
  • Support for non-English locales are not an issue for me so I will not likely implement that. I’m currently using English strings for Perfmon, looking up registry ke6 for each item… maybe later.
  • I decided that there is little reason to distinguish between system volume and others when monitoring free disk space. An extra macro in LLD would do but catch-all seems like a better idea.
  • Currently I copied KB article contents to item descriptions. I guess it sounds like a copyright issue so I have to remove them again.

I also peeked around File Server MP. Checking firewall port rule seems like a good idea but a compact implementation looks next to impossible…