Category: Active Directory


Add Azure CentOs server to Domain


Joining a Linux machine to a Windows domain is not straight forward.

You will need to connect to the server via an SSH app (f.eks Putty)

  1. Sign-in with the admin and password you created when deploying the server
  2. To do some of the commands you will need to be ROOT, but you don’t know this password, so run the following command: sudo -i
    enter the password for the adm account you created
  3. Install realm: yum install realm realmd -y
  4.  Add to domain: realm join yourdomain.com –user youradmin@yourdomain.com
     If you get error: realm: Couldn’t join realm: Necessary packages are not installed: oddjob, oddjob-mkhomedir, sssd, samba-common-tools, you need to install the missing packages.
    f.eks: yum install oddjob -y 

And now the machine is in the domain

 

 

 


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 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.

 

Update UPN on multiple users


I recently did an LDIFDE import of a lot of users to a test domain, and the UPN is not sett on the user objects.

So to change/set the UPN for all my users in the test domain I used this little​ string. Worked like a charm

I gets all the users objects in the Domain Sameie.com, and it sets the UPN to username@sameie.info

Get-ADUser -searchbase “DC=sameie,DC=com” -filter * | foreach {set-adusers $_ -userprincipalname (“{0}@{1}” -f $_.samaccountname,”sameie.info”)}

Count directory Objects in Active Directory


Some times you need to find out how many directory Objects you have in your AD.
A quick way of getting this done is to use the following PowerShell​ string

​​Get-ADObject -Filter {name -like ‘*’} -SearchBase ‘CN=Schema,CN=Configuration,DC=sameie,DC=COM’ -ResultSetSize $null | Measure-Object >c:\tmp\object_dump.txt

This will dump the information into a easy to read text file

object_count_output.PNG

Now you know how many Objects you have.