How to configure a firewall for Active Directory domains and trusts

Applies to: Windows Server 2008 StandardWindows Server 2008 R2 StandardMicrosoft Windows Server 2003 Standard Edition (32-bit x86) More

Summary

This article describes how to configure a firewall for Active Directory domains and trusts.

Note:

Not all the ports that are listed in the tables here are required in all scenarios. For example, if the firewall separates members and DCs, you don't have to open the FRS or DFSR ports. Also, if you know that no clients use LDAP with SSL/TLS, you don't have to open ports 636 and 3269.

More Information

Note

The two domain controllers are both in the same forest, or the two domain controllers are both in a separate forest. Also, the trusts in the forest are Windows Server 2003 trusts or later version trusts.

Client Port(s)	Server Port	Service
1024-65535/TCP	135/TCP	RPC Endpoint Mapper
1024-65535/TCP	1024-65535/TCP	RPC for LSA, SAM, Netlogon (*)
1024-65535/TCP/UDP	389/TCP/UDP	LDAP
1024-65535/TCP	636/TCP	LDAP SSL
1024-65535/TCP	3268/TCP	LDAP GC
1024-65535/TCP	3269/TCP	LDAP GC SSL
53,1024-65535/TCP/UDP	53/TCP/UDP	DNS
1024-65535/TCP/UDP	88/TCP/UDP	Kerberos
1024-65535/TCP	445/TCP	SMB
1024-65535/TCP	1024-65535/TCP	FRS RPC (*)

NETBIOS ports as listed for Windows NT are also required for Windows 2000 and Windows Server 2003 when trusts to domains are configured that support only NETBIOS-based communication. Examples are Windows NT-based operating systems or third-party Domain Controllers that are based on Samba.

(*) For information about how to define RPC server ports that are used by the LSA RPC services, see the following Microsoft Knowledge Base articles:

224196: Restricting Active Directory replication traffic and client RPC traffic to a specific port
"Domain controllers and Active Directory" section in 832017: Service overview and network port requirements for the Windows Server system

Windows Server 2008 and later versions

Windows Server 2008 newer versions of Windows Server have increased the dynamic client port range for outgoing connections. The new default start port is 49152, and the default end port is 65535. Therefore, you must increase the RPC port range in your firewalls. This change was made to comply with Internet Assigned Numbers Authority (IANA) recommendations. This differs from a mixed-mode domain that consists of Windows Server 2003 domain controllers, Windows 2000 Server-based domain controllers, or legacy clients, where the default dynamic port range is 1025 through 5000.

For more information about the dynamic port range change in Windows Server 2008, Windows Server 2012 and Windows Server 2012 R2, see the following resources:

Microsoft Knowledge Base article 929851: The default dynamic port range for TCP/IP has changed in Windows Vista and in Windows Server 2008
Ask the Directory Services Team blog article Dynamic Client Ports in Windows Server 2008 and Windows Vista

Client Port(s)	Server Port	Service
49152 -65535/UDP	123/UDP	W32Time
49152 -65535/TCP	135/TCP	RPC Endpoint Mapper
49152 -65535/TCP	464/TCP/UDP	Kerberos password change
49152 -65535/TCP	49152-65535/TCP	RPC for LSA, SAM, Netlogon (*)
49152 -65535/TCP/UDP	389/TCP/UDP	LDAP
49152 -65535/TCP	636/TCP	LDAP SSL
49152 -65535/TCP	3268/TCP	LDAP GC
49152 -65535/TCP	3269/TCP	LDAP GC SSL
53, 49152 -65535/TCP/UDP	53/TCP/UDP	DNS
49152 -65535/TCP	49152 -65535/TCP	FRS RPC (*)
49152 -65535/TCP/UDP	88/TCP/UDP	Kerberos
49152 -65535/TCP/UDP	445/TCP	SMB (**)
49152 -65535/TCP	49152-65535/TCP	DFSR RPC (*)

NETBIOS ports as listed for Windows NT are also required for Windows 2000 and Server 2003 when trusts to domains are configured that support only NETBIOS-based communication. Examples are Windows NT-based operating systems or third-party Domain Controllers that are based on Samba.

(*) For information about how to define RPC server ports that are used by the LSA RPC services, see the following Microsoft Knowledge Base articles:

224196: Restricting Active Directory replication traffic and client RPC traffic to a specific port
"Domain controllers and Active Directory" section in 832017: Service overview and network port requirements for the Windows Server system

(**) For the operation of the trust this port is not required, it is used for trust creation only.

Note

External trust 123/UDP is only needed if you have manually configured the Windows Time Service to Sync with a server across the external trust.

Active Directory

In Windows 2000 and Windows XP, the Internet Control Message Protocol (ICMP) must be allowed through the firewall from the clients to the domain controllers so that the Active Directory Group Policy client can function correctly through a firewall. ICMP is used to determine whether the link is a slow link or a fast link.

In Windows Server 2008 and later versions, the Network Location Awareness Service provides the bandwidth estimate based on traffic with other stations on the network. There is no traffic generated for the estimate.

The Windows Redirector also uses ICMP Ping messages to verify that a server IP is resolved by the DNS service before a connection is made, and when a server is located by using DFS.

If you want to minimize ICMP traffic, you can use the following sample firewall rule:

<any> ICMP -> DC IP addr = allow

Unlike the TCP protocol layer and the UDP protocol layer, ICMP does not have a port number. This is because ICMP is directly hosted by the IP layer.

By default, Windows Server 2003 and Windows 2000 Server DNS servers use ephemeral client-side ports when they query other DNS servers. However, this behavior may be changed by a specific registry setting. For more information, see Microsoft Knowledge Base article 260186: SendPort DNS registry key does not work as expected

Or, you can establish a trust through the Point-to-Point Tunneling Protocol (PPTP) compulsory tunnel. This limits the number of ports that the firewall has to open. For PPTP, the following ports must be enabled.

Client Ports	Server Port	Protocol
1024-65535/TCP	1723/TCP	PPTP

In addition, you would have to enable IP PROTOCOL 47 (GRE).

Note

When you add permissions to a resource on a trusting domain for users in a trusted domain, there are some differences between the Windows 2000 and Windows NT 4.0 behavior. If the computer cannot display a list of the remote domain's users, consider the following behavior:

Windows NT 4.0 tries to resolve manually-typed names by contacting the PDC for the remote user's domain (UDP 138). If that communication fails, a Windows NT 4.0-based computer contacts its own PDC, and then asks for resolution of the name.
Windows 2000 and Windows Server 2003 also try to contact the remote user's PDC for resolution over UDP 138. However, they do not rely on using their own PDC. Make sure that all Windows 2000-based member servers and Windows Server 2003-based member servers that will be granting access to resources have UDP 138 connectivity to the remote PDC.

Reference

832017: Service overview and network port requirements for the Windows Server system is a valuable resource outlining the required network ports, protocols, and services that are used by Microsoft client and server operating systems, server-based programs, and their subcomponents in the Microsoft Windows Server system. Administrators and support professionals may use this Microsoft Knowledge Base article as a roadmap to determine which ports and protocols Microsoft operating systems and programs require for network connectivity in a segmented network.

You should not use the port information in KB article 832017 to configure Windows Firewall. For information about how to configure Windows Firewall, see the following Microsoft website:

Networking and Access Technologies: Windows Firewall

Last Updated: 28 Apr 2020