IIS Url Rewrite overwriting external urls

Question

On my development machine, I am trying to configure IIS as a reverse proxy to forward requests coming in port 443 to a nodejs application running locally.
The requests are getting forwarded fine, but sometimes the the nodejs application tries to redirect the browser to an external site and the IIS url rewrite module change that also to point to the local server.

I am accessing the site using https://localhost/test
IIS reroutes the requests to the node app http://localhost:14819/test
The node app returns an http 302 with location header set to https://example.com/someroute
IIS transforms this to https://localhost/someroute

I want the external urls to be untouched by IIS. How to do this? Here is my Web.config content

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <clear />                
                <rule name="ReverseProxyInboundRule1" patternSyntax="ECMAScript" stopProcessing="true">
                    <match url="^test(.*)" />
                    <conditions logicalGrouping="MatchAll" trackAllCaptures="false">
                        <add input="{HTTP_HOST}" pattern="^localhost" />
                    </conditions>
                    <action type="Rewrite" url="http://localhost:14819/test{R:1}" logRewrittenUrl="true" />
                </rule>
            </rules>            
        </rewrite>        
    </system.webServer>
</configuration>

Rohith Rohith · Accepted Answer · 2017-07-20T10:49:26

If you have any redirect coming back from the backend proxy and you do not want to redirect the Location header coming ,You can do that by unchecking "Reverse rewritehost in response headers" in Application Request Routing

Select the server node in IIS manager
Go to Application Request routing Cache
Click on Server proxy Settings
UnCheck "Reverse rewritehost in response headers"

IIS Url Rewrite overwriting external urls

1 Answers