Microsoft KB Archive/155252

= Host Name to IP Address Redirection in an IIS URL =

Article ID: 155252

Article Last Modified on 6/23/2005

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APPLIES TO


 * Microsoft Internet Information Server 1.0
 * Microsoft Internet Information Server 2.0

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This article was previously published under Q155252



We strongly recommend that all users upgrade to Microsoft Internet Information Services (IIS) version 6.0 running on Microsoft Windows Server 2003. IIS 6.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site:

http://www.microsoft.com/technet/security/prodtech/IIS.mspx



SYMPTOMS
A client browser accessing a Microsoft Internet Information Server (IIS), using a fully qualified domain name in the URL such as

HTTP://myserver.mycompany.com

or a host/computer name such as

HTTP://myserver

may result in a URL redirection of host name to IP address, for example

HTTP://ipaddress

where ipaddress is your host server's IP address.



WORKAROUND
Below are several ways to work around this issue: two methods to minimize this issue in IIS 1.0, a way to resolve it in IIS 2.0, and a way to resolve the issue by changing the registry of IIS.

Host name to IP address redirection may occur on an IIS version 1.0 or 2.0 server. This issue can be resolved on an IIS version 2.0 server that is accessed by a browser client that also supports the use of Host Headers and can be minimized on an IIS 1.0 server or client browser that does not support the use of Host Headers.

To minimize the IP address redirection on an IIS 1.0 server, use the complete path to the HTML file in the URL, for example:

HTTP://myserver.mycompany.com/samples/default.htm.

-or-

End the URL with a forward slash, for example:

HTTP://myserver.mycompany.com/samples/.

However, the issue may still occur on IIS 1.0.

To resolve the issue in IIS2.0, use Host Headers. Host Headers can help prevent the unexpected substitution of the the IP address for the host name in the URL. Browsers such as the Microsoft Internet Explorer version 3.0 also support the use of Host Headers.

The web master can also make a change to the registry of the IIS 2.0 server to help prevent the IP address redirection on older browser clients. The new registry entry is ReturnURLUsingHostName; its use is described below.

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

 Carry out "Net Stop w3svc". Start Registry Editor (Regedt32.exe).  From the HKEY_LOCAL_MACHINE subtree, go to the following subkey:

     \SYSTEM\CurrentControlSet\Services\W3svc\Parameters The parameter described below is located under this registry subkey.

The following describes a new value for the W3SVC service parameters tree, which can only be set by adding an entry in the Registry Editor. This parameter does not appear by default in the registry, so you must add an entry if you want to change its default value. The W3SVC service must be restarted for changes to take effect.

     ReturnURLUsingHostName Data Type = REG_DWORD Value:

Enter a value of 1.

The default value is 0. This returns the IIS server's IP address to a client browser when doing redirects if the Host Header field is not present.

A value of 1 returns a fully qualified domain name or the host/computer name of the IIS server.

If a fully qualified domain name has been added in the Domain box of the DNS dialog box, the server will return that name; otherwise, it will return the server's computer name, which appears in the Host Name box by default.  To fill in a fully qualified domain name, open the TCP/IP property sheet in the Network tool of the Windows NT Control Panel. Click the DNS tab, and type your domain name in the Domain box, for example mycompany.com. Carry out "Net Start w3svc".</li></ol>

Additional query words: prodiis

Keywords: kbhowto kbnetwork KB155252

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