HTTP Through Firewall and "Bypass Proxy for Local Intranet"

This article was previously published under Q193891
This article has been archived. It is offered "as is" and will no longer be updated.
SYMPTOMS
"Bypass proxy server for local (Intranet) addresses" may not work asexpected.

When a client process attempts to connect to an Internet address (forexample, www.microsoft.com) through a proxy server when the above settingis selected, the first call to tcp_get_host_by_name uses that Internetserver name (www.microsoft.com) as the server. Next, RPC sets up thetunneling, the proxy server redirects the call to the real server(www.microsoft.com), the response packet comes back to the proxy, the proxyredirects it back to the client, and the client sends it to the clientprocess. However, the response packet contains the actual IP address of theInternet server. The client thinks that there is no proxy server andattempts to communicate directly to the Internet IP address that isunreachable; therefore, the connection fails.

If the "Bypass proxy server for local (intranet) addresses" setting is notselected, the call is always directed to the http proxy; however, if you donot select it, you may not be able to communicate or connect to Intranetservers.
CAUSE
The problem is that, if tcp_get_host_by_name() passes an address instead ofa server name, it needs to force a name resolution to make sure the host isreachable.
RESOLUTION
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
152734 How to Obtain the Latest Windows NT 4.0 Service Pack

STATUS
Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.
Properties

Article ID: 193891 - Last Review: 12/05/2015 09:25:54 - Revision: 3.2

Microsoft Windows NT Server 4.0, Terminal Server Edition, Microsoft Windows NT Server 4.0 Standard Edition, Microsoft Windows NT Workstation 4.0 Developer Edition, Microsoft Windows NT Server 4.0 Enterprise Edition, Microsoft BackOffice Small Business Server 4.0, Microsoft BackOffice Small Business Server 4.0a

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