Windows Server 2016 – Blacklist Mobile devices on WIFI network

June 21, 2019

Let’s assume you have 2 WIFI networks. 1 for the Office users and 1 for the Guests on a separate VLAN.

Now you don’t want to have all the Office users using there mobile device to log on to the local LAN.

Most challenging is that if you apply MAC address filtering on the Access Point.

It will block the device on both WIFI networks Sad smile

PREQUISITES :

On your DHCP server you need to activate the BLOCK MAC address filtering

Open the DHCP console and enable the DENY LIST using the FILTERS Tab

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Now you can add the BLOCKED Mac ADDRESSES in the DENY section

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Tip :

You can also use WILDCARDS like this :

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Solution :

Windows 2008r2 :

You can use the NETSH command to block MAC addresses on your local LAN.

netsh dhcp server v4 add filter deny 00-0c-29-fe-dd-60 "Mary's PC"

If you need to automate this on a Windows 2008r2 server you need to apply some regular expressions to grab the  MAC address ,-)

Took me more then a day to figure that out how to make it work Sad smile

Windows 2012r2 and higher :

You can use the DHCP Powershell cmdlets

Get-DhcpServerv4Scope -cn YourServer

Set-DhcpServerv4FilterList -ComputerName "YourServer" -Allow $False -Deny $True

Get-DhcpServerv4FilterList

Add-DhcpServerv4Filter -List Allow -MacAddress "F0-DE-F1-7A-00-5E" -Description "Laptop 09"

Remove-DhcpServerv4Filter -MacAddress "F0-DE-F1-7A-00-5E","F0-DE-F1-7A-00-5E"

See also here how to build a Blacklist for PUBLIC IP addresses.

Enjoy !

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Windows Server 2016 – How to Blacklist Public IP Addresses, Alert Event ID 20271

June 21, 2019

If you notice unauthorised attacks on you network in your event viewer Event ID 20271 Remote Access

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SOLUTION :

Create a BLACKLIST rule using Windows Firewall

Open Windows Firewall with Advanced Security by running wf.msc

On the left, select Inbound Rules, then under the Action menu, choose New Rule

On the Rule Type page, choose Custom.

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On Program, choose “All programs”

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On Protocol and Ports, leave the default of Any

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On Scope, select “These IP addresses” in the remote addresses section and add the problematic IP address in the Add dialog

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On Action, choose “Block the connection”

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On Profile, leave the defaults of everything checked.

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Finally, on Name give the rule a name like “Blacklisting”, and optionally a description.

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See here on how to automate this using PowerShell Event Viewer Scanning & Firewall rules

1. First check if the DENY property is set on your DHCP server

Get-DhcpServerv4FilterList

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If not you can activate it like this

Set-DhcpServerv4FilterList -ComputerName "YourDHCPServer" -Allow $False -Deny $True

Next you can list all IP’s

Get-DhcpServerv4Filter

And check if they exist as blocked.

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If you need to add extra you can use this Cmd

Add-DhcpServerv4Filter -List Deny -MacAddress "F0-DE-F1-7A-00-5E" -Description "iphone 09"

 

See here on how to Blacklist based on MAC Address

 

Safety First …

Done !


Write cache enabled Event ID 32 Error

March 11, 2019

After physical to Virtual conversion, we get this event ID 32 Error on a regular basis..

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The driver detected that the device \Device\Harddisk0\DR0 has its write cache enabled. Data corruption may occur.

Solution :

See here : https://support.microsoft.com/en-ca/help/324805/how-to-manually-turn-disk-write-caching-on-or-off
Turn Disk Write Caching On or Off
  1. Right-click My Computer, and then click Properties.
  2. Click the Hardware tab, and then click Device Manager.
  3. Expand Disk Drives.
  4. Right-click the drive on which you want to turn disk write caching on or off, and then click Properties.
  5. Click the Policies tab.
  6. Click to select or clear the Enable write caching on the disk check box as appropriate.
  7. Click OK.
For Windows Server 2008
  1. Right-click Computer, and then click Properties.
  2. Click the Device Manager link under Tasks.
  3. Expand Disk Drives.
  4. Right-click the drive on which you want to turn disk write caching on or off, and then click Properties.
  5. Click the Policies tab.
  6. Click to select or clear the Enable write caching on the disk check box as appropriate.
  7. Click OK.

To find out the DISK number relation use this SysInternal tool, diskext.exe :

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\Device\Harddisk0\DR0 = C drive

If you see the yellow exclamation mark saying you are not allowed to change the caching …

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See here for more Information :

http://techgenix.com/hyper-v-optimization-tips-part1/

Enjoy!


Windows Server 2016 – Windows Update Center closes immediately

March 10, 2019

Opening the Windows Update Center closes immediately … ?

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The main reason is that the Windows 2016 Software Distribution has become corrupted.

SOLUTION :

Clean the C:\Wndows\SoftwareDistribution folder…

See here for the procedure

https://www.windowscentral.com/how-clear-softwaredistribution-folder-windows-10

After this cleanup everything was back to normal

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Windows Server 2016 – CleanUp Stale Devices – DeviceSetupManager Event ID 121

February 1, 2019

How to cleanup stale devices on your servers …

On one of our servers that is running as a Hyper-V Host and using a non windows backup software to backup the VM’s I see a lot of VSS copies hanging around …. ?

When looking at the HIDDEN devices

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I saw a lot of Generic volume Shadow Copies

See here to know why this is occurs

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And as well INACTIVE Storage volumes

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The know why this is happening see here

Solution :

1. CleanUp all stale devices and registry related entries

Download the DriveCleanup Tool here

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You can run this command to run in TEST MODE

drivecleanup -t > dc-output.txt

You can see this detailed output

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In my case it suggest these entries to be removed.

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I could see a clear relationship between the Event ID 121 Errors and output of the drivecleanup tool

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To delete the stale devices and Registry Keys you need to use the Admin Privileges

Make sure you have good backups before removing anything !

2. Remove all VSS copies

Run this command to cleanup

vssadmin list shadows

vssadmin delete shadows /all

Check again the Event logs after the next backups.

And in my case all disk errors where gone. Smile

Enjoy !


Windows Server 2016 – ServerEssentials DesignatedActiveDirectoryServerDown Event ID 1280 Error

December 20, 2018

After removing a DC and cleaning up the metadata I still got errors relating to DesignatedActiveDirectoryServerDown ?

I rechecked all settings and had still some references in the DNS.

But even after removing all of this it was still complaining ?

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Solution :

Open the registry and go to :

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Server\ADContext

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Key ConnectedDc was pointing to old DC server.

Correct the value and pointed the key to current  DC :

Correct the registry entry by overwriting with the proper value of the local server.

Restart the dashboard for the change to take effect.

Next go on searching for more references in the registry

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https://support.microsoft.com/en-us/help/332199/domain-controllers-do-not-demote-gracefully-when-you-use-the-active-di

If there is an entry for Src Root Domain Srv, right-click the value and then click Delete.

This value must be deleted so that the domain controller sees itself as the only domain controller in the domain after promotion.

Remove these registry key

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\NTDS\Parameters\Src Root Domain Srv 
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Services\NTDS\Parameters\Src Root Domain Srv 
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTDS\Parameters\Src Root Domain Srv 
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\NTDS\Parameters\Src Srv objectGuid 
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Services\NTDS\Parameters\Src Srv objectGuid 
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTDS\Parameters\Src Srv objectGuid
Reboot the server and check again.

Enjoy!


Windows Server 2016 – Disk Event ID 153 Errors

December 18, 2018

I got a lot of Disk Errors Event ID 153 every day when using Windows Backup. Every day at the same time more or less.

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Analysis :

First we need to find out which one is Disk 4 ?

Open the registry and go to : HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\disk\Enum

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You will see that I had 4 Disk, of which the number 4 is a USB Memory card storage…

It will match up with the Server Manager Disks

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Next start the Command Line using Admin Privileges

And run this command

set DEVMGR_SHOW_NONPRESENT_DEVICES=1

devmgmt.msc

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Go to Portable Devices and see check the Drive letters

In my case it is G: drive ?

On the GENERAL tab you can read that the device is NOT ENABLED

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Using WMIC to get more info on the Event ID PDO name Device\00000xxx ID

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Use this command to get all drivers detailed information :

 

wmic /output:c:\temp\drivers.txt path Win32_PnPSignedDriver

And look for the device number in the column PDO

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If you don’t find it, it means it is a STALE device that can be removed.

See here on how to…

Solution :

In our case we had to disable the INTERNAL SD Card Slot using the BIOS.

Use these steps on an HP server :

UEFI System Utilities and Shell Command Mobile Help for HPE ProLiant Gen9 Servers and HPE Synergy

Going to System Utilities – by pressing F9

Enabling or disabling the Internal SD Card Slot

Procedure :

1. From the System Utilities screen, select System Configuration > BIOS/Platform Configuration (RBSU) > System Options > USB Options > Internal SD Card Slot and press Enter.

2. Select a setting and press Enter:

a. Enabled—The server can access the internal SD card slot.

b. Disabled—The server cannot access the internal SD card slot.

3. Press F10.

Enjoy!