You install Microsoft Windows Server 2003 Service Pack 1
(SP1) on a computer that is running Microsoft Internet Security and
Acceleration (ISA) Server 2004, Standard Edition or Microsoft Internet Security
and Acceleration (ISA) Server 2000. After you install the service pack, the ISA
Server remote procedure call (RPC) filter blocks RPC traffic between
- RPC traffic between all other servers is not
- This problem does not occur with ISA Server 2004,
This problem occurs because the ISA Server RPC filter is not
compatible with the changes in the RPC protocol that are introduced by Windows
Server 2003 SP1.
When you enable the ISA Server RPC filter, the RPC
filter enforces strict compliance with a subset of the RPC protocol that is
used by Microsoft Exchange Server MAPI communications. For more information about changes in the RPC protocol
that are introduced by Windows Server 2003 SP1, click the following article
number to view the article in the Microsoft Knowledge Base:
Some firewalls may reject network traffic that originates from Windows Server 2003 Service Pack 1-based computers
ISA Server 2004, Standard Edition
Service pack information
To resolve this problem, install ISA Server 2004 Service Pack 1
(SP1). For more information about how to obtain
the latest ISA Server 2004 service pack, click the following article number to
view the article in the Microsoft Knowledge Base:
How to obtain the latest ISA Server 2004 service pack
ISA Server 2000
A supported update is now available from Microsoft, but it is
only intended to correct the problem that is described in this article. Only
apply it to systems that are experiencing this specific problem. This update
may receive additional testing. Therefore, if you are not severely affected by
this problem, we recommend that you wait for the next Internet Security and
Acceleration Server 2000 or 2004 service pack that contains this
To install this update, you must have ISA Server 2000 Service Pack
You do not have to restart the computer after you install this
The update installer will prompt you to restart ISA services.
You must restart ISA services.
Microsoft recommends that you
disconnect from your Internet service provider when you install this
Update replacement information
This update does not replace any other
following file is available for download from the Microsoft Download
the ISA 2000 RPC Update package now.
Collapse this imageExpand this image
For more information about how to
download Microsoft Support files, click the following article number to view
the article in the Microsoft Knowledge Base:
How to obtain Microsoft support files from online services
Microsoft scanned this file for viruses. Microsoft used the most
current virus-detection software that was available on the date that the file
was posted. The file is stored on security-enhanced servers that help prevent
any unauthorized changes to the file.
The English version of this update has the file
attributes (or later file attributes) that are listed in the following table.
The dates and times for these files are listed in Coordinated Universal Time
(UTC). When you view the file information, it is converted to local time. To
find the difference between UTC and local time, use the Time
tab in the Date and Time tool in Control Panel.
Date Time Version Size File name
12-Dec-2004 05:42 3.0.1200.410 61,944 Rpcfltr.dll
To work around this problem, disable the ISA Server RPC
When you disable the ISA Server RPC filter, you also disable RPC
protocol filtering of traffic that is processed by the ISA Server RPC
Microsoft has confirmed that this is a problem in Microsoft
Internet Security and Acceleration Server 2000 and in Microsoft Internet
Security and Acceleration Server 2004, Standard Edition.