Directory Replicator Replicates directories and files between computers. Event Log Records system, security, and application alerts into the logs you see in Event Viewer. Messenger Sends and receives messages sent by administrators or the Alerter service. Net Logon Used to authenticate a workstation on a domain, or by an NT server to synchronize the domain database with the domain controller.
Schedule Enables the console AT command, used to schedule commands and programs to be run. Server Provides RPC support, file, printer, and named pipe sharing. Spooler Provides printer spooler services.
UPS Manages an uninterruptible power supply connected to the computer. Workstation Provides network connections and communications. Editor's Picks. The best programming languages to learn in Check for Log4j vulnerabilities with this simple-to-use script. TasksBoard is the kanban interface for Google Tasks you've been waiting for. Paging Zefram Cochrane: Humans have figured out how to make a warp bubble. Show Comments. Hide Comments. My Profile Log out.
Join Discussion. Add your Comment. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information, see How to back up and restore the registry in Windows.
The RPC Port key values discussed below are all located in the following key in the registry:. Specifies a set of IP port ranges consisting of either all the ports available from the Internet or all the ports not available from the Internet.
Each string represents a single port or an inclusive set of ports. For example, a single port may be represented by , and a set of ports may be represented by If any entries are outside the range of 0 to , or if any string can't be interpreted, the RPC runtime treats the entire configuration as invalid. If Y, the ports listed in the Ports key are all the Internet-available ports on that computer.
If N, the ports listed in the Ports key are all those ports that aren't Internet-available. If Y, the processes using the default will be assigned ports from the set of Internet-available ports, as defined previously.
If N, the processes using the default will be assigned ports from the set of intranet-only ports. In this example, ports through inclusive have been arbitrarily selected to help illustrate how the new registry key can be configured. It isn't a recommendation of a minimum number of ports needed for any particular system. Restart the server. All applications that use RPC dynamic port allocation use ports through , inclusive.
You should open up a range of ports above port Because of that, trusts with Windows NT 4. Enabling Domain member: Digitally encrypt or sign secure channel data always prevents establishing a secure channel with any domain controller that cannot sign or encrypt all secure channel data. To help protect authentication traffic from man-in-the-middle attacks, replay attacks, and other kinds of network attacks, Windows-based computers create a communication channel that is known as a secure channel through the Net Logon service to authenticate computer accounts.
Secure channels are also used when a user in one domain connects to a network resource in a remote domain. This multidomain authentication, or pass-through authentication, allows a Windows-based computer that has joined a domain to have access to the user account database in its domain and in any trusted domains.
To enable the Domain member: Digitally encrypt or sign secure channel data always setting on a member computer, all domain controllers in the domain that the member belongs to must be able to sign or encrypt all secure channel data.
This means that all such domain controllers must be running Windows NT 4. Enabling the Domain member: Digitally encrypt or sign secure channel data always setting automatically enables the Domain member: Digitally encrypt or sign secure channel data when possible setting. Risky configuration Enabling the Domain member: Digitally encrypt or sign secure channel data always setting in domains where not all domain controllers can sign or encrypt secure channel data is a harmful configuration setting.
Reasons to enable this setting Unsigned network traffic is susceptible to man-in-the-middle attacks, where an intruder captures packets between the server and the client and then modifies them before forwarding them to the client. You can lower the risk of such an attack on a corporate network by implementing strong physical security measures to help protect the network infrastructure.
Additionally, implementing Internet Protocol security IPSec authentication header mode can help prevent man-in-the-middle attacks. This mode performs mutual authentication and packet integrity for IP traffic. Not all domain controllers in the domain have the appropriate service pack revision levels to support encrypted secure channels.
Existing down-level trusts may also not authenticate users from the trusted domain. Some users may have problems logging on to the domain, and they may receive an error message that states that the client cannot find the domain. Windows cannot connect to the domain either because the domain controller is down or is otherwise unavailable or because your computer account was not found. SMB signing authenticates both the user and the server that hosts the data.
If either side fails the authentication process, data transmission will not occur. The SMB signing policies determine whether the computer always digitally signs client communications. The Windows SMB authentication protocol supports mutual authentication. Mutual authentication closes a "man-in-the-middle" attack. The Windows SMB authentication protocol also supports message authentication.
Message authentication helps prevent active message attacks. The client and the server each verify the digital signature. If SMB signing is enabled on a server, clients that are also enabled for SMB signing use the packet signing protocol during all subsequent sessions. If SMB signing is required on a server, a client cannot establish a session unless the client is enabled or required for SMB signing. Enabling digital signing in high-security networks helps prevent the impersonation of clients and of servers.
This kind of impersonation is known as session hijacking. An attacker who has access to the same network as the client or the server uses session hijacking tools to interrupt, end, or steal a session in progress. An attacker could intercept and modify unsigned SMB packets, modify the traffic, and then forward it so that the server might perform unwanted actions.
Or, the attacker could pose as the server or as the client after a legitimate authentication and then gain unauthorized access to data. Mutual authentication closes session hijacking attacks and supports message authentication. Therefore, it prevents man-in-the-middle attacks. The client and the server then verify the signature. As an alternative countermeasure, you can enable digital signatures with IPSec to help protect all network traffic.
There are hardware-based accelerators for IPSec encryption and signing that you can use to minimize the performance impact from the server's CPU. There are no such accelerators that are available for SMB signing. Configure SMB signing through Group Policy Object Editor because a change to a local registry value has no effect if there is an overriding domain policy. Additionally, Windows servers do not respond to SMB signing requests from these clients. For more information, see item "Network security: Lan Manager authentication level.
Risky configuration The following is a harmful configuration setting: Leaving both the Microsoft network client: Digitally sign communications always setting and the Microsoft network client: Digitally sign communications if server agrees setting set to "Not Defined" or disabled. These settings allow the redirector to send plain text passwords to non-Microsoft SMB servers that do not support password encryption during authentication.
Reasons to enable this setting Enabling Microsoft network client: Digitally sign communications always requires clients to sign SMB traffic when contacting servers that do not require SMB signing. This makes clients less vulnerable to session hijacking attacks. Enabling Microsoft network client: Digitally sign communications always prevents clients from communicating with target servers that do not support SMB signing.
Configuring computers to ignore all unsigned SMB communications prevents earlier programs and operating systems from connecting. You will not be able to map a network drive from a client with this setting enabled, and you will receive the following error message:. Restart requirements Restart the computer, or restart the Workstation service. To do this, type the following commands at a command prompt. Press Enter after you type each command.
An attacker could intercept and modify unsigned Subnet Bandwidth Manager SBM packets, modify the traffic, and then forward it so that the server might perform unwanted actions.
Risky configuration The following is a harmful configuration setting: Enabling the Microsoft network server: Digitally sign communications always setting on servers and on domain controllers that are accessed by incompatible Windows-based computers and third-party operating system-based client computers in local or external domains.
All client computers that enable this setting directly through the registry or through the Group Policy setting support SMB signing. In other words, all client computers that have this setting enabled run either Windows 95 with the DS client installed, Windows 98, Windows NT 4. If Microsoft network server: Digitally sign communications always is disabled, SMB signing is completely disabled.
Completely disabling all SMB signing leaves computers more vulnerable to session hijacking attacks. Enabling this setting will prevent clients that cannot negotiate SMB signing from communicating with servers and with domain controllers. This causes operations such as domain joins, user and computer authentication, or network access by programs to fail. Windows Windows 95 clients that do not have the Directory Services DS Client installed will fail logon authentication and will receive the following error message:.
The system could not log you on. Make sure your username and your domain are correct, then type your password again. Some non-Microsoft SMB servers support only unencrypted password exchanges during authentication. These exchanges also known as "plain text" exchanges. For Windows NT 4. The account is not authorized to login from this station.
Windows Server By default, security settings on domain controllers that run Windows Server are configured to help prevent domain controller communications from being intercepted or tampered with by malicious users.
For users to successfully communicate with a domain controller that runs Windows Server , client computers must use both SMB signing and encryption or secure channel traffic signing. By default, clients that run Windows NT 4. Therefore, these clients may not be able to authenticate to a Windows Server based domain controller. Windows and Windows Server policy settings: Depending on your specific installation needs and configuration, we recommend that you set the following policy settings at the lowest entity of necessary scope in the Microsoft Management Console Group Policy Editor snap-in hierarchy:.
Send unencrypted password to connect to third-party SMB servers this setting is for Windows Microsoft network client: Send unencrypted password to third-party SMB servers this setting is for Windows Server The following clients are incompatible with the Microsoft network server: Digitally sign communications always setting:.
Restart requirements Restart the computer, or restart the Server service. For example, the following operating systems, services, or applications may not work:. Users in Windows NT 4. Reasons to disable this setting If this setting is enabled, a malicious user could use the well-known Administrators SID to obtain the real name of the built-in Administrator account, even if the account has been renamed.
That person could then use the account name to initiate a password-guessing attack. The Network access: Do not allow anonymous enumeration of SAM accounts setting determines which additional permissions will be granted for anonymous connections to the computer. Windows allows anonymous users to perform certain activities, such as enumerating the names of workstation and server Security Accounts Manager SAM accounts and of network shares.
For example, an administrator can use this to grant access to users in a trusted domain that does not maintain a reciprocal trust. Once a session is made, an anonymous user may have the same access that is granted to the Everyone group based on the setting in the Network access: Let Everyone permissions apply to anonymous users setting or the discretionary access control list DACL of the object.
Typically, anonymous connections are requested by earlier versions of clients down-level clients during SMB session setup. RPC may also try to make anonymous connections. Important This setting has no impact on domain controllers. In Windows , a similar setting called Additional Restrictions for Anonymous Connections manages the RestrictAnonymous registry value. The location of this value is as follows. Risky configurations Enabling the Network access: Do not allow anonymous enumeration of SAM accounts setting is a harmful configuration setting from a compatibility perspective.
Disabling it is a harmful configuration setting from a security perspective. Reasons to enable this setting An unauthorized user could anonymously list account names and then use the information to try to guess passwords or to perform social engineering attacks. Social engineering is jargon that means tricking people into revealing their passwords or some form of security information. Reasons to disable this setting If this setting is enabled, it is impossible to establish trusts with Windows NT 4.
This setting also causes problems with down-level clients such as Windows NT 3. Windows 95, Windows Windows 95 clients and Windows 98 clients will not be able to change their passwords. Windows 95, Windows Windows based and Windows based computers will not be able to be authenticated by Microsoft domain controllers.
Windows 95, Windows Users on Windows based and Windows based computers will not be able to change the passwords for their user accounts. Windows allows anonymous users to perform certain activities, such as enumerating the names of domain accounts users, computers, and groups and of network shares.
This is convenient, for example, when an administrator wants to grant access to users in a trusted domain that does not maintain a reciprocal trust. If you do not want to allow anonymous enumeration of SAM accounts and of shares, enable this setting.
The location of this value is as follows:. Risky configuration Enabling the Network access: Do not allow anonymous enumeration of SAM accounts and shares setting is a harmful configuration setting. Enabling the Network access: Do not allow anonymous enumeration of SAM accounts and shares setting prevents enumeration of SAM accounts and shares by users and computers that are using anonymous accounts.
If this setting is enabled, an unauthorized user could anonymously list account names and then use the information to try to guess passwords or to perform social engineering attacks.
Social engineering is jargon that means tricking people into revealing their password or some form of security information. If this setting is enabled, it will be impossible to establish trusts with Windows NT 4. This setting will also cause problems with down-level clients such as Windows NT 3. It will be impossible to grant access to users of resource domains because administrators in the trusting domain will not be able to enumerate lists of accounts in the other domain.
Users who access file and print servers anonymously will not be able to list the shared network resources on those servers. The users must authenticate before they can view the lists of shared folders and printers. The following error message will appear when RestrictAnonymous is enabled on the trusted domain:. Windows Windows based member computers in Windows NT 4. Windows Windows domain users will not be able to add network printers from Active Directory; however, they will be able to add printers after they select them from the tree view.
Outlook clients: The global address list will appear empty to Microsoft Exchange Outlook clients. Additionally, Advanced clients cannot communicate with the Management Point. Anonymous access is required on the Management Point. Background LAN Manager LM authentication is the protocol that is used to authenticate Windows clients for network operations, including domain joins, accessing network resources, and user or computer authentication.
Specifically, the LM authentication level determines which authentication protocols that the client will try to negotiate or that the server will accept.
This value affects the level of authentication protocol that clients use, the level of session security negotiated, and the level of authentication accepted by servers. Possible settings include the following. Find the correct location where you can change the LAN manager authentication level to set the client and the server to the same level. One effect of incompatible settings is that if the server requires NTLMv2 value 5 , but the client is configured to use LM and NTLMv1 only value 0 , the user who tries authentication experiences a logon failure that has a bad password and that increments the bad password count.
If account lock-out is configured, the user may eventually be locked out. For example, you may have to look on the domain controller, or you may have to examine the domain controller's policies. Look on the domain controller Note You may have to repeat the following procedure on all the domain controllers.
Click Start , point to Programs , and then click Administrative Tools. Double-click Network Security: LAN manager authentication level , and then click a value in the list. If the Effective Setting and the Local Setting are the same, the policy has been changed at this level. If the settings are different, you must check the domain controller's policy to determine whether the Network Security: LAN manager authentication level setting is defined there.
If it is not defined there, examine the domain controller's policies. Examine the domain controller's policies. You may also have to check policies that are linked at the site level, the domain level, or the organizational unit OU level to determine where you must configure the LAN manager authentication level.
0コメント