Category: Windows


How can I see what OS version my Azure VM is running?


I wanted to check what OS version I had deployed on a server in Azure, but I couldn’t remember if it was 2012 R2 or 2016.

I checked the server object in Azure and it gave me this

Hmmm…. that didn’t really answer my question (yes I could connect via RDP, but some times you can’t)

I know there are several scripts you can run to get information (that will need a connection, running scripts and so on, not everyone has this access, so they should be able to view this without scripts)

So I decided to check the disk connected to the server, and that gave me a better answer ūüôā

There I can see it was a 2012 R2 DC based on the image 4.127….

 

So in the Resource group (or on VM) find the disk for the server, and you will see the Disk info in the Overview.

Enjoy

Get system uptime


We all have our own ways of finding a servers / computers uptime.
But I thought I’d share my favorite way:

 

function Get-SrvUptime
{
$operatingSystem = Get-WmiObject Win32_OperatingSystem
[Management.ManagementDateTimeConverter]::ToDateTime($operatingSystem.LastBootUpTime)
}


Restarting a service with Task Scheduler


Some times you need to scheduler a restart of services on servers or computers, and I used to do this via a batch job, that I called from Task Scheduler, but..

I found a much easier way of doing this,  just create a new task, and add the Actions like bellow.

NET as the program, and START/STOP “SERVICENAME” as the argument

and¬†voila, there it is ūüôā


HTTP 400 IIS Token Bloat


An old “friend” keeps keeps showing up in different environments. So since my old Blog is gone, I will add this again.
But this time I’ll just copy the info from Microsoft’s website.

Thank you Microsoft:¬†https://support.microsoft.com/en-us/help/2020943/-http-400—bad-request-request-header-too-long-error-in-internet-info

 

HTTP 400 – Bad Request (Request Header too long)” error in Internet Information Services (IIS)

Symptoms

A domain user attempts to browse to a website hosted on Internet Information Services (IIS) 6.0 or higher by using Internet Explorer 6.0 or later.  The website is configured to use Kerberos authentication.  Instead of receiving the expected web page, the user is presented with an error message similar to the following:

HTTP 400 – Bad Request (Request header too long)

 

Cause

This issue may occur when the user is a member of many Active Directory user groups. When a user is a member of a large number of active directory groups the Kerberos authentication token for the user increases in size. The HTTP request that the user sends to the IIS server contains the Kerberos token in the WWW-Authenticate header, and the header size increases as the number of groups goes up.  If the HTTP header or packet size increases past the limits configured in IIS, IIS may reject the request and send this error as the response.

 

Resolution

To work around this problem, choose one of the following options:

A) Decrease the number of Active Directory groups that the user is a member of.

OR

B) Modify the MaxFieldLength and the MaxRequestBytes registry settings on the IIS server so¬†the user’s request headers are¬†not considered too long.¬† To determine the appropriate settings for the MaxFieldLength and the MaxRequestBytes registry entries, use the following calculations:

    1. Calculate the size of the user’s Kerberos token using the formula described in the following article:

      New resolution for problems with Kerberos authentication when users belong to many groups
      http://support.microsoft.com/kb/327825

    2. Configure the MaxFieldLength and the MaxRequestBytes¬†registry keys on the IIS server with a value of¬†4/3 * T, where¬†T¬†is the user’s token size, in bytes.¬†¬†HTTP encodes the Kerberos token using base64 encoding and therefore replaces every 3 bytes in the token with 4 base64 encoded bytes.¬† Changes that are made to the registry will not take effect until you restart the HTTP service. Additionally, you may have to restart any related IIS services.

 

NOTE: Depending on your application environment, you could also consider configuring the web site to use NTLM instead of Kerberos to work around this problem.  Some application environments require Kerberos to be used for delegation purposes, and Kerberos is more secure than NTLM, so it is recommended that you do not disable Kerberos before considering the security and delegation ramifications of doing so.

 

More Information

By default, the MaxFieldLength registry entry is not present. This registry entry specifies the maximum size limit of each HTTP request header. The MaxRequestBytes registry entry specifies the upper limit for the total size of the Request line and the headers. Typically, this registry entry is configured together with the MaxRequestBytes registry entry. If the MaxRequestBytes value is lower than the MaxFieldLength value, the MaxFieldLength value is adjusted.  In large Active Directory environments, users may experience logon failures if the values for both these entries are not set to a sufficiently high value.

For Internet Information Services (IIS) 6.0 and later, the MaxFieldLength and MaxRequestBytes registry keys are located at HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters.  Configure them as shown in the following table:

 

Name  Value Type  Value Data
 MaxFieldLength  DWORD  (4/3 * T bytes) + 200
 MaxRequestBytes  DWORD  (4/3 * T bytes) + 200

 

Alternatively you may set the registry keys to their maximum values shown below. The Administrator should consider all potential security ramifications if he makes any changes to the registry settings:

Name  Value Type Value Data
 MaxFieldLength  DWORD  65534
 MaxRequestBytes  DWORD  16777216

 

IMPORTANT: Changing these registry keys can be considered extremely dangerous. These keys allow larger HTTP packets to be sent to IIS, which in turn may cause Http.sys to use more memory and may increase vulnerability to malicious attacks.

 

NOTE: If MaxFieldLength is configured to its maximum value of 64KB, then the MaxTokenSize registry value should be set to 3/4 * 64 = 48KB.  For more information on the MaxTokenSize setting, please see the Microsoft knowledge base article KB327825 listed below.

 

No more download 1 GB Test files


Tired of looking on the web for a big test file, or creating your own locally?
Then this is perfect for you too ūüôā
Open CMD in administrator mode
Run the following command:
fsutil file createnew <file> <size in bytes>
F.eks this will create a 10 GB file in my tmp folder:
fsutil file createnew c:\tmp\10gb.test 10737418240
The key is to input the size of the file in bytes so here are some common file sizes to save you from math:
1 MB = 1048576 bytes
100 MB = 104857600 bytes
1 GB = 1073741824 bytes
10 GB = 10737418240 bytes
100 GB =107374182400 bytes
1 TB = 1099511627776 bytes
10 TB =10995116277760 bytes