Microsoft KB Archive/907427

= When SecureNAT clients try to access an external network through an ISA Server 2004, Enterprise Edition computer, ISA Server does not perform network address translation =

Article ID: 907427

Article Last Modified on 12/4/2007

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APPLIES TO


 * Microsoft Internet Security and Acceleration Server 2004 Enterprise Edition

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SYMPTOMS
When secure network address translation (SecureNAT) clients try to access an external network through a Microsoft Internet Security and Acceleration (ISA) Server 2004, Enterprise Edition computer, ISA Server does not perform network address translation (NAT).

Additionally, a Network Monitor trace may show that ISA Server routes internal traffic to the external network instead of performing network address translation.

Note When you restart the Domain Name System (DNS) service on the internal DNS server or restart the Firewall service on the ISA Server computer, the problem is temporarily resolved.



CAUSE
This problem occurs because ISA Server does not substitute the source IP address that is contained in the TCP/IP header with the IP address of the NAT device.



RESOLUTION
To resolve this problem, obtain the latest service pack for ISA Server 2004, Enterprise Edition. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

891024 How to obtain the latest ISA Server 2004 service pack



STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the &quot;Applies to&quot; section.

Keywords: kbqfe kbprb KB907427

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