How to configure a firewall for Active Directory domains and trusts

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

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.
 

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:
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

For more information about Active Directory and firewall configuration, see the Active Directory in Networks Segmented by Firewalls Microsoft white paper.