How to Troubleshoot AD Replication using Repadmin Tool
Repadmin is a cmd application for diagnosing AD replication issues. Via Repadmin it is easy to view replication topology for every domain controller. And use this knowledge to manually change it and initiate replication communications between controllers. With Repadmin you can easily check replication metadata and relevance vectors (up-to-dateness (UTDVEC)).
Repadmin.exe is a built-in feature in Windows Server environment starting from 2008. It comes with AD Directory Services role and also can be setup in client OSes like Windows 10 with RSAT.
Repadmin.exe has lots of commands, lets focus on most popular ones:
/syncall – used to synchronize a certain DC with others
/prp – if you have a Password Replication Policy (PRP), this command helps to manage it
/queue – Shows the current queue of replication
/replicate – this command helps to perform replication from one DC to another
/replsingleobj – This command is handy if you need to replicate only one certain object between DCs
/replsummary – Shows a report of a current state of replication and health in AD
/showattr – is used when you need to see object attributes
/showbackup – this setting displays the last backup time
/showrepl – If you need to know current replication status use this one
How to Get General Replication Status
Let’s start from overall state of replication, run elevated cmd.exe (start->run->cmd.exe) and type in the following command:
The output will show you any replication failures that exist in your AD environment.
How to Force Replication
Suppose you have replication failures and you need to force a replication after fixing networking connections failure. In elevated Command Prompt (cmd.exe) on any DC run:
repadmin.exe /syncall /Aped
In addition to /syncall command we have few flags that will synchronize all partitions (/A), using push notifications (/p), in enterprise mode across Active Directory sites (/e) using distinguished names instead of DNS names (/d).
How to Manage Inbound and Outbound Replication
It is possible to disable inbound and/or outbound replication with a possibility to reenable it later. To achieve that run the following commands in cmd under admin rights:
repadmin.exe /options DC01 +DISABLE_INBOUND_REPL
Disables inbound replication on a DC01
repadmin.exe /options DC01 +DISABLE_OUTBOUND_REPL
Disables outbound replication on a DC01
repadmin.exe /options DC01 -DISABLE_INBOUND_REPL
Enables inbound replication on a DC01
repadmin.exe /options DC01 -DISABLE_OUTBOUND_REPL
Enables outbound replication on a DC01
For example, the option to disable outbound replication is a good way to perform schema updates without the need to rebuild the entire Active Directory forest.
Users are one of the most popular objects in AD. They are used for authentication and authorization on workstations. Also in many services which are integrated with AD. User management is the main routine for sysadmins and helpdesk specialists. This guide helps to manage such objects in multiple ways. For managing users there is a need to install RSAT tools or manage them from your DC. You have to be signed under domain admin or an Account Operators user or with delegation rights to create objects in the current OU.
Creating User Accounts
Deleting User Accounts
Moving User Accounts
Renaming User Accounts
Enabling User Accounts
Disabling User Accounts
Setting Expiration Period for an Account
Finding Locked-out Accounts
Unlocking User Accounts
Modifying Several Users in Bulk
Creating a User Account
There are many ways to create a user account in AD, lets consider several of them.
Creating User Account Using Active Directory Users and Computers(ADUC)
Run ADUC (dsa.msc).
Go to OU where new users should be located. In the taskbar, click the “New User” icon, or right-click on a white space in the main window and then click on “New -> User“. Another way is rightclicking the needed Org Unit and select “New -> User“.
“New Object — User” appears, specify parameters for your user:
• Full name, by either typing the full name into Full Name field or typing it in the First and Last name fields.
• User logon name, this field creates the userPrincipalName and the sAMAccountName attributes.
Click Next and specify strong password and then retype it in the next field and check the needed parameters, usually for regular user you should check “User must change password at next logon”.
Click Next and Finish. Congratulations new user was successfully created!
Creating User Account Using Command Prompt
To make the same thing in cmd we need to use dsadd.exe utility. The following parameters will help to create a user in “Users” container in AD and set default password for it:
Lets delete a user from AD environment, follow these easy methods. Note that this action will not completely delete a user account with enabled AD Recycle Bin, it will change its token attributes and move it to deleted objects.
Deleting User Account in Active Directory Users and Computers(ADUC)
Lets delete one user, to achieve that open Active Directory Users and Computers (dsa.msc).
Go to the OU or container where the user that you need to delete resides. Click on the Action menu or rightclick the OU and select Find.
Type in the name or last name of the user you want to delete into the name field and click “Find Now”. The results will be displayed to you, select the object you need to delete, rightclick it and then click on Delete and confirm your decision.
Deleting User Account Using Command Prompt
The following cmd string will delete a user “GSoul” from office.local domain:
dsrm.exe user "CN=GSoul,CN=Users,DC=office,DC=local"
Deleting User Account Using PowerShell
Execute the following PowerShell code to delete a user GSoul from AD:
Moving a User Account via Active Directory Users and Computers(ADUC)
In ADUC (dsa.msc) go to the OU or container with needed user account. Rightclick it and select Find…. In the Name field, type the name of the user account and then click Find Now… From the list of Search results, select the needed user object.
Right-click on the user account. Select Move… from the menu.
The Move window appears:
In the Move window, navigate to the OU or container where you want to move the user object to, select it and click OK.
Moving a User Account via Command Prompt
In order to move user object(GSoul in our case) to “Employees” OU run dsmove.exe in cmd with the following parameters:
In order to rename a user account, follow these several instructions.
Renaming a User Account via Active Directory Users and Computers
In Active Directory Users and Computers (dsa.msc) in the View menu, enable Advanced Features.
Navigate to OU or container where needed user object resides. Right-click it and select Find…. In the Name field, type the name of the user and press “Find Now”. From the search results right-click the needed user account and select Rename. Type the new name and press Enter.
In the Rename User window, enter new data for other attributes and click OK.
Renaming a User Account via Command Prompt
Use dsmove.exe with the following parameters in order to rename a user:
How to Enable and Disable a User Account in Active Directory
If you want to stop a user logging into their workstation you can disable it, but you need it again for some reason, for example, an employee returned from maternity leave, you can enable it again. Here is the guide to do that in multiple ways.
Enabling and Disabling a User Account Using Active Directory Users and Computers
To enable/disable a user in ADUC, follow these steps:
In ADUC (dsa.msc). Determine the OU or container storing needed accounts. Rightclick it and select Find…. In the Name field, type the name of the user account and then click Find Now… From the list of Search results, select the needed user object, right-click it and select Enable account or Disable account depending on what you need right now and click OK.
Enabling/Disabling a User Account Using cmd.exe
These tasks are for dsmod.exe, use it with the following settings to enable an account.
dsmod.exe "CN=GSoul,CN=Users,DC=office,DC=local" -disabled no
And this will disable it:
dsmod.exe user "CN=GSoul,CN=Users,DC=office,DC=local" -disabled yes
Enabling and Disabling a User Account Using Windows PowerShell
Here is the PowerShell code to enable a user account:
How to Set Account Expiration Period to a User Account
User accounts can be set to automatically expire after certain period of time.
Setting Account Expiration Period in ADUC
To set account expiration in ADUC, follow these simple steps:
In ADUC (dsa.msc) go to the OU or container with needed user account. Rightclick it and select Find…. In the Name field, type the name of the user account and then click Find Now… From the list of Search results, select the needed user object. Right-click it and select Properties. Select the Account tab, at the bottom of this tab, change the Never option for “Account expires:” to End of:, and select needed date. Click OK to save the changes.
Setting Account Expiration Period Using cmd.exe
Use the dsmod.exe to set the quantity of days before an account expires:
dsmod.exe user "CN=GSoul,CN=Users,DC=office,DC=local" -acctexpires 90
Setting Account Expiration Period Using Windows PowerShell
To set user expiration period in Employees OU execute the following PowerShell script:
User accounts may get locked-out for some reason and you need to troubleshoot the cause of account lockout, but first of all you need to get the list of them. There are several ways to get this list.
Finding Locked User Accounts with the Active Directory Administrative Center
Run Active Directory Administrative Center (dsac.exe). Select the OU or container where you want to search for locked out users. Expand the top bar by clicking on an arrow button in the right top corner.
Click on Add criteria and select the “Users with enabled but locked accounts” criteria. Click Add and the locked-out accounts will be displayed.
Finding Locked User Accounts with Windows PowerShell
In order to find locked out accounts in AD, user the following PowerShell script:
Account lockout in one of the most often cases for sysadmins in organization. Sometimes it is even hard to get its cause so it requires deep investigation. But it is not the point to disable an account lockout policy because it helps to protect your user accounts from brute force attacks. In this guide we will focus on easy techniques to unlock users.
Unlocking User Accounts via Active Directory Administrative Center
To unlock a user object, open the Active Directory Administrative Center (dsac.exe), navigate to the OU or container where users exist in. Right-click the object you want to unlock and select Properties.
In the User window click the Unlock account and then OK.
To unlock all locked-out accounts in a certain OU or container select the OU or container where you want to search for locked out users. Expand the top bar by clicking on an arrow button in the right top corner. Click on Add criteria and select the “Users with enabled but locked accounts criteria.” Click Add and the locked-out accounts will be displayed. Select all accounts, go to Properties and click on Unlock account.
Unlocking User Accounts via Windows PowerShell
To unlock a user account, you need to run the following PowerShell code:
Sometimes there is the need to modify one attribute for multiple objects. Modifying multiple objects at once is slightly different task from editing a single user, and there are several ways to achieve that.
Modify Several Users at Once Using ADUC
ADUC is great when you need simple filters to group users by certain criteria. It has selection mechanism, for example you can select multiple different users with Ctrl button pressed or a chunk with Shift button pressed. You can also easily select all users in an OU or container by pressing Ctrl + A.
So, you need to change some settings in multiple user accounts, let’s do that with AD:
In ADUC (dsa.msc) locate the OU that fits your needs. Select the user objects while the Shift button being pressed. Rightclick all these objects and select Properties.
Change the given attributes according to your needs and click OK.
Modify Several Users at Once Using Active Directory Administrative Center
The ADAC differs from ADUC by providing additional filters.
Run ADAC and select the OU to use as the base scope for the filter.
Expand the top bar by clicking on little arrow button at top right corner. Click the Add criteria button:
Add the criteria you want to use such as “Users with expired passwords” or you can create a filter by one of the attributes. Select the filter and click Add to load it. You can use matches such as starts with, equals, does not equal, is empty, and is not empty.
After you receive the list of objects based on your filter press Ctrl+A to select all of them and click Properties.
Change attributes that you want to modify and click OK.
Modify Several Users at Once Using Windows PowerShell
Filter customization in PowerShell is more advanced, it is best used to modify multiple user objects, repeatedly.
In our example we will filter all accounts with name starting with “admin” and enable “Prevent from accidental deletion” for all these accounts:
When you join a computer to the Active Directory domain or create a user, all these objects will be placed in default containers – Computers and Users. In order to place your new objects to relevant OUs with proper group policies you need to change their default location. This tutorial will show you how to do that.
Modification the default location for new user and computer objects is possible in Windows Server 2003 and above. And you need to have a user account with domain admin rights and perform commands directly from the server not from a management workstation.
By default design, new computers are stored in Computers container and new users in the Users container because containers can’t have policies linked, so even if there is a problem with AD because of GPOs there should be a possibility to join a device and sign in to it without group policies.
Modifying the Default Location for User and Computer Objects
First, we need to create or decide the OUs to which we want to redirect. One for computers another for users. In our example it will be Employees and Workstations. For this purpose, Microsoft created redirusr.exe and redircmp.exe which are located in %SystemRoot%\System32 folder.
Run Command Prompt (cmd.exe) as administrator, run the following commands, replacing the values for your environment:
Logon scripts can be very handy when we need certain actions been done with a user logon such as mapping a network drive. This tutorial will show you how to assign a logon script using Group Policies.
In order to do that your account must have Domain Admin rights, delegated “edit GPO settings” rights or be an owner of the GPO.
There are four types of script you can use with Group Policy:
Logon scripts (User Configuration)
Logoff scripts (User Configuration)
Startup scripts (Computer Configuration)
Shutdown scripts (Computer Configuration)
In this example we will be focused on Logon Scripts.
Assigning Logon Scripts via Group Policy Management Console
Run Group Policy Management Console (GPMC.msc) on a domain workstation or server where it is installed.
In the left pane, expand your domain Forest -> Domains and then navigate to the domain where you want to assign a logon script.
Expand the domain name and then expand the Group Policy Objects.
Select the GPO or create a new one for assigning a script. Right-click GPO and select “Edit”.
• The window with Group Policy Management Editor (gpedit.msc) appears. • Expand User Configuration -> Policies -> Windows Settings. • Then select Scripts and double click «Logon». • In the Logon window, click the Add… button. • The “Add a Script” window appears:
• Type path to your script in the “Script Name:” field or browse to its location by clicking on “Browse…” button. • In the “Script Parameters:” field, type any optional script parameters. • Click “OK” to save the script settings and “OK” to close the “Logon Properties” window. • Close the Group Policy Management Editor and link your policy to and organizational unit (OU) where you want logon scripts to run. • To do that click on an organizational unit and then click on “Link an Existing GPO”.
• Choose the GPO we’ve just edited and click “OK”. After that right-click on the Organizational Unit and select “Update Group Policy”. In the appeared windows click on “Yes”.
Now all workstations in the OU will get our group policy with logon script and after reboot and user login the script will be executed.
In this article we will cover the installation and configuration of the OpenVPN server based on Linux CentOS, and show how to connect two remote computers (or offices) behind NAT into one network using OpenVPN server. We will also use certificates for encrypted connection. If you are a Windows user, check out the guide about configuring VPN in Windows server operating system.
What is OpenVPN
How to Install OpenVPN and Easy-RSA
How to Configure Easy-RSA and Issue a Certificate
How to Create Keys and Certificates for the OpenVPN Server
How to Configure OpenVPN Server
How to Configure Firewall with OpenVPN
How to Connect Computers and Networks using OpenVPN
What is Open VPN
Virtual Private Network (VPN) – a set of technologies that allow you to build a secure network over public networks or the Internet. With a VPN, you can consolidate Internet-divided segments of networks into a single local network. OpenVPN – one of the implementations of open source VPN technology based on SSL/TLS. With the help of OpenVPN it is possible to connect in a single network both remote offices and separate local PCs, which are behind firewall with Network Address Translation (NAT).
How to Install OpenVPN and Easy-RSA
First thing you need to do is to connect the ExtraPackagesforEnterpriseLinux (EPEL) repository and update the system:
Press Ctrl+x to exit the file then y to save it and then hit Enter. The file must be executable, so next step is to execute the following:
sudo chmod +x vars
How to Create Keys and Certificates for the OpenVPN Server
Before creating the key, we need to initialize the Public Key Infrastructure (PKI) directory and create the CA key:
sudo ./easyrsa init-pki
Now let’s create a CA key:
sudo ./easyrsa build-ca
After running the command, we will need to specify a password to generate the certificates and key. The password will be required in the future to sign the certificates.
After that the system will ask to enter Distinguished Name (DN) enter your server and domain name for example server.domain.com and create a server key with nopass option which disables the password for domain.com:
sudo ./easyrsa gen-req server.domain.com nopass
During the certificate issuance process, you will be asked to enter Common Name, just press Enter to continue.
Sign the domain.com key using our CA certificate:
sudo ./easyrsa sign-req server server.domain.com
First you need to confirm the request by typing “yes”. After that you will need to enter the password that we set when the CA certificate was issued:
To make sure that the certificates were generated without errors, run the command:
Let’s move on to the settings of the OpenVPN configuration file. First let’s create the OpenVPN configuration file named server.conf:
sudo cd /etc/openvpn/ && nano server.conf
Change the contents of the file to the following:
# Specify port, protocol and device
# Specify path to server certificates
# Paths to CRL and DH keys
# Specify the network IP and mask which the VPN clients will enter
server 10.0.2.0 255.255.255.0
push "redirect-gateway def1"
# Enter the target DNS servers
push "dhcp-option DNS 18.104.22.168"
push "dhcp-option DNS 22.214.171.124"
# Allow users to connect with the same key
# TLS security
tls-auth /etc/openvpn/server/ta.key 0
# Other config
keepalive 20 60
# Log file path
Then we save the file. I specified the default UDP port 1194 for the VPN server, but for OpenVPN you can specify any free port on the server.
How to Configure Firewall with OpenVPN
What remains is to configure firewall rules to allow connection and routing between segments.
If you are using Firewalld, you must first activate the kernel module forwarding:
Let’s check the IP settings of the network interface:
sudo ip a
3: tun0: mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 100
inet 10.0.2.1 peer 10.0.2.2/32 scope global tun0
valid_lft forever preferred_lft forever
inet6 fe80::932a:e40b:ac2f:6b2/64 scope link flags 800
valid_lft forever preferred_lft forever
As you can see, the network specified in the configuration has been added to the tun0.
These are the minimum settings you need to make for OpenVPN to work.
How to Connect Computers and Networks using OpenVPN
How to connect to the OpenVPN server from two remote computers that are connected to the Internet via NAT, and organize a private network between them? To connect a Windows computer to the OpenVPN server you will need the official client from that can be downloaded from the official site. The installation is straightforward, so we will focus on the configuration.
After you have installed the client, you need to go to the configuration file, which you need to create along the way:
Create a file with the name Client.ovpn and add the following content to it:
remote publicVPNserverIP 1194
tls-auth "C:\Program Files\OpenVPN\config.key" 1
remote-cert-eku "TLS Web Server Authentication"
ca "C:\Program Files\OpenVPN\config\ca.crt".
cert "C:\Program Files\OpenVPN\config\admin.crt".
key "C:\Program Files\OpenVPN\config\admin.key".
As you can see we need the client, security and server certificates and keys we created earlier to configure. They need to be downloaded from the OpenVPN server and placed in a C:\Program Files\OpenVPN\config\ directory.
After that we connect through the shortcut Open VPN client in the tray:
Once connected, both computers are on the same network and ping each other. Both connected VPN clients can exchange packets and transfer files directly to each other. This way, we were able to combine two PCs located in different parts of the world into one local network.
On your OpenVPN server you can create an unlimited number of keys and certificates for users. If you need a new certificate, run the following commands in /etc/openvpn/easy-rsa/3:
sudo ./easyrsa gen-req client name nopass
sudo ./easyrsa sign-req client name
Remember to periodically revoke client certificates if they are not used to keep your network secure.
GPResult.exe – is a console application designed to analyze settings and diagnose group policies that apply to a computer and/or user in an Active Directory domain. Specifically, GPResult provides the resulting set of policies (RSOP), a list of applied domain policies (GPOs), their settings, and detailed information about processing errors. The utility has been part of the Windows operating system since Windows XP. The GPResult utility let you know whether a particular policy applies to a computer, which GPO has changed a particular Windows setting, and why it takes so long for GPP/GPO to apply, even if you’ve run gpupdate /force.
In this article, we will look at how you can use the GPResult command to troubleshoot and debug the application of Group Policy in an Active Directory domain.
Resultant Set of Policies (RSOP)
How to Use GPResult Utility
How to Get RSOP HTML Report via GPResult
How to Get GPResult Data From a Remote Computer
How to Get RSOP Data for a Certain User
Possible Reasons for GPOs to not Apply
Resultant Set of Policies (RSOP)
Initially, the RSOP.msc graphical console was used to diagnose the application of group policies in Windows, which allowed the resulting policy settings (domain + local) to be applied to the computer and the user in a graphical interface similar to the GPO editor console.
However, the RSOP.msc console does not make sense in modern versions of Windows, as it does not reflect the settings applied by various client side extensions (CSEs), such as GPP (Group Policy Preferences). Also, it does not allow searching, and provides little diagnostic information. Therefore, the GPResult command that is the primary tool for troubleshooting GPOs in Windows. Moreover, in Windows 10, there is even a warning that RSOP does not provide a full report as opposed to GPResult.
How to Use GPResult Utility
In order to check for group policy enforcement the GPResult command have to be run on the computer where you want to check for it. The GPResult command has the following syntax:
To learn more about Group Policies that apply to the following AD object (user and computer) and other settings related to the GPO infrastructure (i.e. the resulting GPO policy settings – RsoP), run the command:
The results of the command execution are divided into 2 sections:
COMPUTER SETTINGS – this section contains information about GPO operating on the computer
USER SETTINGS – user policies (policies that apply to the user account in AD)
Let’s briefly run through the main settings/partitions that may be useful in GPResult output:
Site Name – the name of the AD site where the computer is located;
CN – full canonical user/computer name for which RSoP data were generated;
Last time Group Policy was applied – the time when Group Policy was last applied;
Group Policy was applied from – the domain controller from which the latest version of the GPO was downloaded;
Domain Name and Domain Type – the name and version of the Active Directory domain schema;
Applied Group Policy Objects – lists of active Group Policy Objects;
The following GPOs were not applied because they were filtered out – not applied, filtered GPOs;
The user/computer is a part of the following security groups – domain groups that the user belongs to.
In our example, you can see that there are 3 Group Policies that apply to the user object.
Default Domain Policy;
If you do not want the console to display both user and computer policies at the same time, you can use the /scope option to display only the needed section. For example here is the command for user settings:
gpresult /r /scope:user
And here is for the computer policies:
gpresult /r /scope:computer
Since the Gpresult utility outputs its data directly to the command line console, which is not always convenient for further analysis, its output can be redirected to the clipboard:
Gpresult /r |clip
or a text file:
Gpresult /r > c:\gpresult.txt
To output RSOP super detailed information, you need to add the /z key:
Gpresult /r /z
How to Get RSOP HTML Report via GPResult
In addition, the GPResult utility can generate an HTML report on the applied resulting policies (available in Windows 7 and above). This report will contain detailed information about all system settings that are set by Group Policies. The resulting report is structured like the Settings tab in the Domain Group Policy Management Console (GPMC). You can generate a GPResult HTML report using the following command:
GPResult /h c:\temp\GPreport.html /f
To generate a report and then automatically open it in your browser, follow the command:
GPResult /h GPReport.html & GPReport.html
The gpresult HTML report contains quite a lot of useful information:
GPO’s application errors
Processing time in ms
Application of specific policies and CSE (that are located in Computer Details ⇒ Component Status)
As you can see, this HTML report is much more useful for analyzing the policies than the rsop.msc console.
How to Get GPResult Data from a Remote Computer
GPResult can also collect data from a remote computer, eliminating the need for the administrator to log on to the remote computer locally or via RDP. The syntax of the command to collect RSOP data from the remote computer is the following:
GPResult /s servername /r
Similarly, you can remotely collect data by both user and computer policies.
How to Get RSOP Data for a Certain User
When UAC is enabled, running GPResult without elevated privileges displays only the user’s group policy settings. If you want to display both settings at the same time (User and computer settings), you need to run the command with administrative privileges. If the cmd.exe with elevated privileges is run on an account that differs from the current system user, the utility will generate an INFO warning: The user “domain\user” does not have RSOP data. This happens because GPResult is trying to collect information for the user who started it, but because the user has not logged on, there is no RSOP information for him. To collect RSOP information for a user with an active session, you need to specify their account:
gpresult /r /user:domain\username
If you do not know the name of an account that is logged on to a remote computer, the account can be obtained this way:
Also check the time (and time zone) on the client. The time must correspond to the time on the PDC (Primary Domain Controller).
Possible Reasons for GPOs to not Apply
While troubleshooting group policies, you should also take a look at the section: “The following GPOs were not applied because they were filtered out“. This section displays a list of GPOs do not apply to this object. Policy may not apply due to following options:
Filtering: Not Applied (Empty) – the policy is empty (there’s nothing to apply);
Filtering: Denied (Unknown Reason) – It is likely that the user or computer does not have permission to read/apply this policy. Permissions can be configured in the Security tab in the Group Policy Management Console (GPMC);
Filtering: Denied (Security) – the “Apply Group Policy” section has an explicit deny permission, or the AD object is not listed in the Security Filtering section of the GPO settings.
You can also understand whether the policy should apply or not to a specific AD object on the Advanced ⇒ Effective Access tab.
So, these are all options for the Group Policies diagnostic features using the GPResult utility.
How to Update Windows Group Policy on Domain Computers
In this article, we will take a look at the features of updating Group Policy settings on Active Directory domain computers:
Automatic Group Policy update interval
The GPUpdate command
Remote update via the Group Policy Management Console (GPMC.msc)
PowerShell Invoke-GPUpdate command
Group Policy Update Interval
In order for the new settings that you have defined in a Local or Domain Group Policy (GPO) to apply to clients, the Group Policy Client service must reload the policies and make changes to the client settings. This process is called updating Group Policies. Group Policy settings are updated when the computer boots up and the user logs on, or automatically in the background every 90 minutes plus random offset between 0 and 30 minutes (i.e., the policies are guaranteed to apply to clients between 90 and 120 minutes after the GPO files are updated on the domain controller).
Domain controllers by default update the GPO settings much more frequently – once every 5 minutes. You can change the refresh interval for GPO settings using the Set Group Policy refresh interval for computers option, which is located in the GPO Computer Configuration ⇒ Administrative Templates ⇒ System ⇒ Group Policy section. Enable the policy and set the time (in minutes) in the following settings:
This setting allows you to customize how often Group Policy is applied to computers (0 to 44640 minutes) – if you specify 0 here, the policies will start to update every 7 seconds – you should not do this
This is a random time added to the refresh interval to prevent all clients from requesting Group Policy at the same time (0 to 1440 minutes) – the maximum value of a random time interval that is added as an offset to the previous setting.
Keep in mind that frequent GPO updates result in increased traffic to domain controllers and increased network load.
GPUpdate.exe – Group Policy Settings Update Command
All administrators are familiar with the gpupdate.exe command, which allows you to update group policy settings on your computer. Many of them do not hesitate to use the gpupdate /force command to update the GPO. This command forces the computer to reread all the policies from the domain controller and reapply all settings. The client accesses the domain controller, and receives ALL policies that are targeting it. This puts an increased load on the network and the domain controller.
A simple gpudate without /force key command applies only the new/changed GPO settings.
If all is OK when we update the GPO, the following lines should appear:
Computer Policy Update has completed successfully.
User Policy Updating has completed successfully.
If any policies or settings have not applied, use the gpresult command to troubleshoot.
You can separately update GPO user settings by running the following command:
or just computer policies:
gpupdate /target:computer /force
If some policies cannot be updated in the background, gpudate can force the logoff of the current user:
gpupdate /target:user /logoff
Or reboot the computer (if the GPO changes can only be applied when Windows boots):
Force Update of Group Policy from the Group Policy Management Console
GPMC.msc (Group Policy Management Console), starting with Windows Server 2012, provides the ability to remotely update Group Policy settings on domain computers.
In Windows 10, you will need to install the RSAT component to use this console. In order to install it run the following command with administrator privileges:
Now, after changing the settings or creating and linking a new GPO, all you have to do is right click on the desired Organizational Unit (OU) in the GPMC and select Group Policy Update from the context menu. In the new window, you will see the number of computers that will update the GPO. Confirm the forced policy update by clicking Yes.
Then, the GPO begin to update on each computer in the OU and you get a result with the status of the policy update on the computers (Succeeded/Failed).
This command remotely creates a scheduled task on the computers with the GPUpdate.exe /force command for each logged user. The task starts at a random time interval (up to 10 minutes) to reduce the network load.
The following conditions must be met for this GPMC functionality to work on the client:
TCP port 135 needs to be opened in Windows Firewall
Windows Management Instrumentation and Task Scheduler services must be enabled
If the computer is shut down or access to it is blocked by the firewall, the message “The remote procedure call was cancelled” will appear next to the computer name.
In a nutshell, this functionality would have the same effect if you had manually updated the policy settings on each computer with the GPUpdate /force command.
Group Policy Update with Invoke-GPUpdate Powershell Command
You can also trigger remote Group Policy updates on computers using the Invoke-GPUpdate PowerShell cmdlet (included in the RSAT). For example, you can use the command to remotely update user policies on a specific computer:
You can specify a random delay in updating a GPO using the RandomDelayInMinutes setting. In this case you can reduce the load on the network if you want to update policies on multiple computers at the same time. The RandomDelayInMinutes 0 setting is used to apply the policies immediately.
For inaccessible computers, the command will return the error:
Invoke-GPUpdate: Computer "spb-srv01" is not responding. The target computer is either turned off or Remote Scheduled Tasks Management Firewall rules are disabled.
When running the Invoke-GPUpdate command remotely or updating a GPO through the GPMC, a cmd window may briefly appear on the user’s monitor with the gpupdate command running.
In this article, we’ll step by step describe how to deploy the Direct Access (DA) remote connection service on Microsoft Windows Server. Before we get started, let’s take a quick look at what the Direct Access service is. The Direct Access component was first introduced by Microsoft in Windows Server 2008 R2 and was designed to provide transparent access for remote computers to internal company network resources. When connecting through a DA, the user can take full advantage of the enterprise and domain services, and the IT support staff can manage and keep the computers up to date in terms of security. At its core, Direct Access is a lot like a traditional VPN connection to the corporate network. You can also call it “always on VPN”.
Difference Between Direct Access and VPN
Let’s look at the basic difference between Direct Access and VPN:
In order to establish the Direct Access connection, the user does not need to start the VPN client – the connection is made automatically when there is Internet access.
To establish a connection between the DA client and the server, you need to open port 443.
The user’s computer must be in an Active Directory domain.
The communication channel between the remote PC and the corporate gateway is encrypted with robust algorithms using IPsec.
It is possible to organize two-factor authentication using a one-time password system.
Difference Between the First Version of Direct Access and Latest
What are the major differences between the new Windows Server versions of Direct Access and the first version on Windows 2008 R2? The main difference is the reduced requirements for the related infrastructure. For example, here are some differences:
The Direct Access server no longer needs to be an edge server, it can now be behind NAT.
If you’re using Windows 8 Enterprise and later as the remote client, you don’t need to deploy an internal PKI infrastructure (client authentication will be handled by the Kerberos proxy located on the DA server).
Having IPv6 on the internal network of the organization is not necessary.
New Direct Access supports OTP (One Time Password) and NAP (Network Access Protection) without requiring Unified Access Gateway (UAG) deployment.
Direct Access Installation Requirements
Here are infrastructure requirements to deploy Direct Access based on Windows Server:
Active Directory domain and domain administrator rights.
A dedicated (recommended) DA server running Windows Server 2012 R2 and later, included in a Windows domain. The server has 2 network cards: one is on the internal corporate network and the other is on the DMZ network.
Dedicated DMZ subnet.
The external DNS name or IP address available from the Internet that Direct Access clients will connect to.
Traffic redirection configuration from TCP port 443 to DA server address.
Deployed PKI infrastructure for certificate issuance. The certificate authority must publish the Web Server certificate template and allow it to be auto-enrolled (Not needed for Windows 8 and above).
Clients must run Windows Professional / Enterprise edition.
AD Group that will consist of computers that are allowed to connect to the network via Direct Access.
Installing Remote Access Server Role
First we need to start the Server Manager console and use the Add Roles and Features wizard to install the Remote Access role.
As part of the Remote Access role, you must install the Direct Access and VPN (RAS) service.
Leave all other settings by default and restart the server after installation.
Configuring the Direct Access Service in Windows Server
Once the Remote Access service has been installed, open the Tools ⇒ Remote Access Management snap-in.
The remote access console will start. Click on DirectAccess and VPN ⇒ Run the Remote Access Setup Wizard. Now we only need to install Deploy DirectAccessonly role.
This should open a window in the right half of which you can see the four steps (Step 1 – 4) of the DA service configuration graphically.
Step One: Remote Clients
Let’s say that we’re deploying full DirectAccess for client access and remote management.
Now you need to specify the AD security group that will contain the computer accounts that are allowed to connect to the corporate network via Direct Access (in this example, we will use alwayonvpn group).
Enable DirectAccess for mobile only option – allows you to limit connection via DA only for mobile devices (laptops, tablets). This feature is implemented by polling clients via WMI.
The Force Tunneling option – means that remote clients when accessing any remote resources (including regular websites) always use DA servers (all external client traffic goes through the corporate gateway).
On the next step we need to specify a list of internal network names or URLs from which the client can check (Ping or HTTP request) that he is connected to the corporate network. You can also specify the help desk email address and the name of the DirectAccess connection (so that it will appear on the client’s network connections).
If necessary, you can enable the Allow DirectAccess clients to use local name resolution option, which allows the client to use the company’s internal DNS servers (DNS server addresses can be obtained by DHCP).
Step Two: Remote Access Server
The next step is to configure the Remote Access server. In our example we will have an edge server (firewall) with two network cards, so we need to select – Behind an edge device (with two network adapters), one of which is on the corporate network and the other is connected directly to the Internet or DMZ subnet. You also need to provide the external DNS name or IP address on the Internet (which is where port 443 is pinged to the external interface of the DirectAccess server) that the DA clients should connect to.
Then you must specify which NIC will be considered Internal (LAN) and which External (DMZ).
Now we need to generate a DA server certificate. To do this, create a new mmc snap-in, and add the Certificates console that manages local computer certificates.
In the Certificate Management Console, request a new personal certificate by clicking on Certificates (Local Computer) ⇒ Personal ⇒ Certificates and selecting All Tasks ⇒ Request New Certificate…
Request a certificate through the Active Directory Enrollment Policy. We are interested in a certificate based on the Web Servers template.
In the new certificate request settings on the Subject tab, let’s fill out the fields that identify our company and on the Private Key tab, let’s specify that the certificate private key can be exported (Make private key exportable).
Save the changes and request a new certificate from CA. Request and generate a new certificate.
Return to the DirectAccess server settings window and click the Browse button to select the generated certificate. Specify our certificate.
In the next step of the wizard, we’ll select a method for authenticating Direct Access clients. Specify that authentication with Active Directory credentials (username/password) is used. Select the checkbox of Use computer certificates and Use an intermediate certificate. Click the Browse button to specify the certificate authority that will be responsible for issuing client certificates.
Step Three – Infrastructure Servers
The third stage contains configuration of infrastructure servers. We need to specify the address of the Network Location Server, which is located inside the corporate network. Network Location Server (NLS) – is a server through which the client can determine that it is on the internal network of the organization, i.e. you do not need to use DA to connect. NLS server can be any internal web server (even with a default IIS page), the main requirement is that the NLS server must not be accessible from outside the corporate network.
Now let’s specify a list of DNS servers for name resolution by clients. It is recommended to leave the option Use local name resolution if the name does not exist in DNS or DNS servers are unreachable when the client computer is on a private network (recommended).
Then specify the DNS suffixes of internal domains in order of priority of their use.
Management settings window we will keep default.
Step Four – Application Servers
In this step we will configure application servers. This phase allows you to configure additional authentication and traffic encryption between the back-end application servers and DA clients. In this example we do not need this, so let’s leave the option Do not extend authentication to application servers.
This completes the Remote Access role configuration wizard, so we just need to save the changes.
After you finish, the wizard will create two new group policies – DirectAccess Client Settings and DirectAccess Server Settings that are attached to the root of the domain. You can either leave them as they are, or link them to the desired OU.
Test Direct Access on the Windows Client
To test how Direct Access works from the client side, let’s add a computer with Windows Enterprise OS to our direct access group (alwaysonvpn) and update Group Policy via gpupdate /force on it.
Disconnect the laptop from the corporate network and connect to the Internet via public Wi-Fi. The system automatically connects to the corporate network via DirectAccess. The connection name will be displayed in Network & Internet Settings.
You can verify if there is a DirectAccess established using the PowerShell command:
If it returns ConnectedRemotely, then the DA is connected to the corporate network
In this article we will take a look at the features of Remote Desktop Protocol (RDP) connection auditing and log analysis in Windows. Typically, it is useful when investigating various incidents on Windows servers when a system administrator is required to provide information about what users logged on to the server, when he logged on and off, and from which device (name or IP address) the RDP user was connecting.
Remote Desktop Connection Events
Like other events, the Windows RDP connection logs are stored in the event logs. The Windows logs contain a lot of information, but it can be difficult to find the right event quickly. When a user remotely connects to a Windows server, many events are generated in the Windows logs. We will take a look at the following:
Network Connection Events
Network Connection connects user’s RDP client with the Windows server. That logs EventID – 1149 (Remote Desktop Services: User authentication succeeded). The presence of this event does not indicate successful user authentication. This log can be found at Applications and Services Logs ⇒ Microsoft ⇒ Windows ⇒ Terminal-Services-RemoteConnectionManager ⇒ Operational. You can filter this log by right clicking on Operational log ⇒ Selecting “Filter Current Log” and type in EventID 1149.
The result is a list with the history of all network RDP connections to this server. As you can see, the log file contains the username, domain (When Network Level Authentication (NLA) authentication is used), and IP address of the computer from which the RDP connection is made.
User authentication can be successful or unsuccessful on the server. Navigate to Windows logs ⇒ Security. We are interested in logs with EventID – 4624 (An account was successfully logged on) or 4625 (An account failed to log on). Pay attention to the LogonType value in the event. LogonType – 10 or 3 indicates a new logon to the system. If LogonType is 7, it indicates re-connection to an existing RDP session.
The username of the connecting account is written in the Account Name field, his computer name is written in Workstation Name, and the IP address in Source Network Address.
Take a look at TargetLogonID field, which is a unique user session identifier that can be used to track further activity of this user. However, if a user disconnects from the RDP session and reconnects to the session again, the user will be issued a new TargetLogonID (although the RDP session remains the same).
You can get a list of successful authentication events over RDP (EventID 4624) using the following PowerShell command:
RDP logon is the event that appears after successful user authentication. Log entry with EventID – 21 (Remote Desktop Services: Session logon succeeded). This log can be found in Applications and Services Logs ⇒ Microsoft ⇒ Windows ⇒ TerminalServices-LocalSessionManager ⇒ Operational. As you can see here you can see the RDP Session ID for the user.
“Remote Desktop Services: Shell start received” details in EventID 21 means that the Explorer shell has been successfully launched in the RDP session.
Session Disconnect and Reconnect Events
Session Disconnect/Reconnect events have different codes depending on what caused the user to end the session, for example disable by inactivity, selecting “Disconnect” in Start menu, RDP session drop by another user or administrator, etc. These events can be found in Applications and Services Logs ⇒ Microsoft ⇒ Windows ⇒ TerminalServices-LocalSessionManager ⇒ Operational. Let’s take a look at the RDP events that may be of interest:
EventID – 24 (Remote Desktop Services: Session has been disconnected) – the user has disconnected from the RDP session.
EventID – 25 (Remote Desktop Services: Session reconnection succeeded) – The user has reconnected to his existing RDP session on the server.
EventID – 39 (Session A has been disconnected by session B) – user disconnected from his RDP session by selecting the appropriate menu item (not just closed the RDP client window by clicking on “x” in the top right corner). If the session IDs are different, then the user has been disconnected by another user or administrator.
EventID – 40 (Session A has been disconnected, reason code B). Here you should look at the reason code for the disconnection in the event. For example:
Reason code 0 (No additional information is available) – usually indicates that the user just closed the RDP client window.
Reason code 5 (The client’s connection was replaced by another connection) – the user re-connected to his old session.
Reason code 11 (User activity has the disconnect) – the user clicked the Disconnect button on the menu.
EventID – 4778 in Windows log ⇒ Security (A session was reconnected to a Window Station). The user re-connected to an RDP session (the user is given a new LogonID).
EventID 4799 in Windows Logon ⇒ Security (A session was reconnected to a Window Station). Disconnection from an RDP session.
Logoff logs track the user disconnection from the system. In the Applications and Services Logs ⇒ Microsoft ⇒ Windows ⇒ TerminalServices-LocalSessionManager ⇒ Operational logs we can find EventID 23. In this case in Security log we need to search for EventID 4634 (An account was logged off).
Event 9009 (The Desktop Window Manager has exited with code (x)) in the System log shows that the user initiated the end of the RDP session and the user’s window and graphical shell were terminated. Below is a small PowerShell that uploads the history of all RDP connections for the current day from the Remote Desktop Service server. The table below shows the connection time, client IP address, and RDP username (you can include other logon types in the report if necessary).
Sometimes it is needed to export RDP logs into Excel table, in this case you can upload any Windows log to a text file and afterwards import it into Excel. You can export the log from the Event Viewer console or from the command line:
Zabbix is an open-source enterprise level monitoring system. At the moment Zabbix is one of the most popular and functional free monitoring systems, with its easy installation and configuration. Zabbix server can be used for monitoring large infrastructures with hundreds of servers, as well as for small environment. In this article we will cover how to install and configure free monitoring system Zabbix with Linux Ubuntu based web interface. Install Zabbix agents on Windows and Linux server, and add new hosts to the system for monitoring.
Zabbix structure and functionality
Installing Zabbix server on Linux
Configuring Zabbix web interface
Installing Zabbix agent on Windows
Adding a device on a Zabbix server
Installing Zabbix agent on Linux
Zabbix Structure and Functionality
Zabbix is rather simple to install and configure. It is written in C++ (server, proxy and agent) and PHP (frontend). Zabbix server and Zabbix proxy can only run on Linux systems. The agent can be installed on many supported operating systems and platforms.
The Zabbix server installation package consists of:
Zabbix server binary
MySQL (MariaDB)/PostgreSQL databases
Apache2/Nginx web server with PHP frontend
Frontend files – .php, .js, .css, etc…
The scheme of work looks like this:
The Zabbix agent sends data to the server
The Zabbix server receives and processes the data
If the received data is subject to the specified conditions, a trigger is triggered
An active trigger signals a problem. A notification is displayed on the frontend, the notification emails is sent and needed actions are automatically performed. This depends on the configuration, for example Zabbix agent can restart the service that is being monitored.
Zabbix can work with all known protocols, thanks to a system of external scripts.
Installing Zabbix Server on Linux
In this article we will take a look at an example installation of Zabbix Server on Linux (using Ubuntu Server) through a batch manager.
Go to the download page https://www.zabbix.com/download and select the repository corresponding to your Linux distribution. Ready-made packages are available for all popular distributions.
For example, to install Zabbix 5 on Ubuntu 18.04 you have to select :
Zabbix Version 5 ⇒ OS Distribution (Ubuntu) ⇒ OS Version (18.04 Bionic) ⇒ Database (MySQL) ⇒ Web Server (Nginx or Apache).
Now you need to configure the frontend (web interface) of Zabbix. Open the previously specified URL of Zabbix server in your browser. In our example it is test.zabbix.local. Do not forget to register it on your DNS server.
Make sure that all installer requirements are OK.
Enter the data to connect to the database. Use the user and password you created earlier.
Enter the name of the Zabbix server. I recommend not to change the standard port – TCP 10051.
Note. The default Zabbix system uses two ports:
TCP 10050 is a passive agent port, on which the zabbix server polls clients;
TCP 10051 – the port on which zabbix server receives data from clients (active agent).
After that press Next Step and Finish. After successful installation, you will need to log in. Use “Admin” as login and “zabbix” as password, these are the default credentials.
This concludes the installation of the Zabbix Server.
Select the desired version of the agent for Windows. For this example we will choose the “.msi x64” format (without OpenSSL). If you plan to install zabbix agent on servers/computers via Group Policy or SCCM, you can download the zip archive with binary and configuration files.
Start the installer, accept the license agreement, specify the requested data. Note that in the “Server or Proxy for active checks” field I entered the IP address in “IP:PORT” format. Since I left the port as standard, it will be serverip:10051.
Then click Next and Install.
Now we need to make sure that our agent is installed. The Zabbix agent service should appear in the services.msc list.
On the Windows client Firewall, you need to allow incoming connections from the Zabbix server:
To make sure that the agent is working, you need to add our host to the Zabbix server and assign it checks.
Note. There are two types of checks in the Zabbix: Passive – the Zabbix server asks for some data from the agent; Active – the agent sends data to the server;
While installing the agent, we specified a server in IP:PORT format just for active checks.
Adding Device on a Zabbix Server
So We’ve installed the agent, now we need to add it on the monitoring platform via web-interface. Go to Configuration ⇒ Hosts ⇒ Click Create host and fill in the data. Note that the host’s name must match the host name of the server with the agent or the value of the Hostname parameter in the agent config.
On the Templates tab, add some built-in Windows templates. Templates in Zabbix are sets of values, triggers, graphs and detection rules that can be assigned to one or more hosts.
These integrated templates have “active” in the end, which means that active checks will be used.
Click Add. To avoid waiting for the server and agent to connect with each other (usually takes a couple of minutes), restart the Zabbix Agent service on monitored host and check the agent’s log (C:\Program Files\Zabbix Agent\zabbix_agentd.txt).
The message “started [active checks #1]” indicates that active checks for this host have been found on the server. Now let’s look at the data that came to the Zabbix server from the agent. To do this in Zabbix, go to Monitoring ⇒ Latest Data and select the desired host in the Hosts field.
This section shows the latest data that came to the server by selected hosts or groups of hosts. Note that there is a notification on the Zabbix dashboard that the BITS service is not running. This notification appears because we have assigned standard templates to our host. One of the templates was monitoring the BITS service and the corresponding trigger, which is triggered if the BITS service is not in status Running.
This concludes the configuration of the Windows Agent.
Installing the Zabbix Agent on Linux
Now let’s install the Zabbix agent on Linux. To install the Zabbix agent in Ubuntu Server using the package manager you need to download and install the Zabbix repository. Then we will install the zabbix agent from the repository:
“Cannot parse list of active checks” string indicates that there are no active checks for this host on the server.
Similar to the Windows agent, you need to add your Linux host to the Zabbix server settings. Note the Hostname parameter in the host configuration in the server’s Zabbix interface must match the Hostname parameter that we specify in the Zabbix config.
Reboot the Zabbix agent and check the log.
Check that the agent data has appeared on the Zabbix server.
This completes the configuration of the Zabbix agent on your Linux system.