FIX: Cannot Renew DHCP Assigned IP Address on External ISA Interface (326116)


The information in this article applies to:

  • Microsoft Internet Security and Acceleration Server 2000
  • Microsoft Internet Security and Acceleration Server 2000 SP1
This article was previously published under Q326116

SYMPTOMS

On a computer running Internet Security and Acceleration Server, where the external interface is configured to have its IP address dynamically assigned from DHCP, you may not be able to renew the IP address on the interface.

For example, if you run ipconfig /release, followed by ipconfig /renew, from a command prompt, you may receive an error message similar to the following:
The following error occurred when renewing adapter MyAdapterName: DHCP Server unreachable
Additionally, you may not be able to turn off and turn on the external network adapter, or to automatically or manually change the assigned IP address on the external network adapter in ISA Server.

This problem also occurs when you have the DHCP Client Static Packet filter turned on in ISA Server.

The only way to renew the IP address is to temporarily turn off packet filtering or restart the computer running ISA Server.

CAUSE

The DHCP Client Static Packet filter only permits you to refresh the already assigned external IP address.

For example, when the DHCP lease has expired and the IP address on the external interface is lost or manually released, a renew of the IP address is blocked by the ISA Server Packet Filter module. The ISA service is not fully Plug and Play when the IP address is released on the external interface. Therefore, packet filtering is still applied to the interface.

RESOLUTION

You must install ISA Server Service Pack 1 (SP1) before you install the following hotfix. For additional information about how to obtain the latest ISA Server service pack, click the article number below to view the article in the Microsoft Knowledge Base:

313139 How to Obtain the Latest Internet Security and Acceleration Server 2000 Service Pack

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Internet Security and Acceleration Server 2000 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

To install the fix, run the self-extracting file. You do not have to restart the ISA Server computer. If the computer is part of an ISA Server array, you do not have to shut down the whole array. You can still install this fix on a one-by-one basis.

The English version of this fix has the file attributes (or later) 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 Zone tab in the Date and Time tool in Control Panel. 
Date          Time    Version        Size      File name 
--------------------------------------------------------
24-Oct-2002   20:21   3.0.1200.179   176,912   Mspadmin.exe 
24-Oct-2002   20:20   3.0.1200.179   388,368   W3proxy.exe 
24-Oct-2002   20:21   3.0.1200.179   297,232   Wspsrv.exe 
24-Oct-2002   20:21   3.0.1200.179    99,600   Msphlpr.dll
This fix also applies to the French, German, Spanish, and Japanese versions of ISA Server.

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

MORE INFORMATION

Note that after you install this hotfix, while you are renewing the DHCP assigned IP address, you may receive an event notice in the Application Event Log similar to the following:
Event Type: Warning
Event Source: Microsoft Firewall
Event ID: 14223
Description:
The description for Event ID (14223) in Source (Microsoft Firewall) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer.
The following information is part of the event:
This event may be logged if some of the packet filters could not be restored when the interface is re-created by using the new IP address. As a result, some active connections may be dropped during the renewal process.
When you release the DHCP assigned IP address, you may also receive an event message similar to the following:
Event Type: Warning
Event Source: Microsoft ISA Server Control
Event Category: Packet filter
Event ID: 15108
Description:
ISA Server detected a spoof attack from Internet Protocol (IP) address 10.10.10.10. A spoof attack occurs when an IP address that is not reachable via the interface on which the packet was received. If logging for dropped packets is set, you can view details in the packet filter log.
For example, this event may appear in the log if the packet filter is currently handling a packet. While you change the IP address on the external adapter, this causes routing table changes in the operating system (OS). Because ISA Server does spoof detection by comparing the interface on which the packet was received to the interface from which a reply to the originating source would be sent, it would consider this to be a spoofed packet if the two interfaces are different.

The following is still not supported after you install this hotfix:
  • If you change the IP address on the internal network adapter, SecureNAT stops functioning.

    NOTE: Such changes are rare because in a SecureNAT scenario, the internal IP address of the ISA Server computer should never use DHCP, which must be configured as a gateway on the router or on all computers in the local internal subnet.
  • Dynamic filters for listeners that bind to IP 0.0.0.0 are not opened in the following scenarios:
    • A new external IP is added after the filters for the listener were created.
    • An external network adapter that is not a Routing and Remote Access service demand-dial (that existed when dynamic filters for the listener were created) is turned off, and receives a new IP when it is turned on. The only ISA application filter that opens the listener is the H.323 filter, which opens TCP port 1720 for incoming calls.
  • Local Address Table (LAT) changes that change the status of a network adapter from external to internal, or from internal to external, are not supported. In this case, ISA Management also prompts you to restart the ISA services.
Modification Type:MinorLast Reviewed:10/11/2005
Keywords:kbHotfixServer kbQFE ATdownload kbbug kberrmsg kbfix kbISAServ2000preSP2fix kbQFE KB326116
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