Iis – Reverse Proxy on Virtual Directory in IIS7

iisreverse-proxyrewrite

I am running a WHS 2011 and try to proxy an internal webserver (subsonic) over IIS7. The goal is:

https://external_host/subsonic -> http://internal_host:4040

What I've done so far:

Created a Virtual Directory "subsonic" in the Default Web Site
List item

Created the Rewrite Rules

Whenever I call the URL https://external_host/subsonic I'll get a 404 while trying to access https://external_host/login.view. login.view is in fact the login page of the internal web server.

Here's the config on the Virtual Directory "subsonic":

    <rewrite>
        <rules>
            <rule name="ReverseProxyInboundRule1" stopProcessing="true">
                <match url="(.*)" />
                <action type="Rewrite" url="http://homeserver:4040/{R:1}" />
            </rule>
        </rules>
        <outboundRules>
            <rule name="ReverseProxyOutboundRule1" preCondition="ResponseIsHtml1">
                <match filterByTags="A, Form, Img" pattern="^http(s)?://homeserver:4040/(.*)" />
                <action type="Rewrite" value="http{R:1}://www.external.com/{R:2}" />
            </rule>
        </outboundRules>
    </rewrite>

Is it possible to run a Reverse Proxy on a Virtual Directory at all?

Best Answer

IIS Application Request Routing (ARR) is the perfect solution to this. We are doing this today proxying a public facing domain to an internally hosted web farm. Basically it is using rewrite rules to accomplish this, but it provides a few extra goodies for reverse proxy as well.

Related Solutions

IIS7 remove file extension

You need to change the rule to use regular expressions instead of wildcards. This is because the R:1 is a regexp backreference.

Also - you probably want your pattern to be (.*) for it to be R:1 (most likely it will be R:0 without the parens - R:0 is the backreference for "the entire match")

Check out http://learn.iis.net/page.aspx/497/user-friendly-url---rule-template/ for lots of info on the user friendly URL portion of URL Rewrite.

Reverse Proxy – should virtual directory/subfolders match rewrite rules

There is an undocumented issue with ARR / rewrite, where it cannot map subfolders. I am adding this for my reference and hoping it helps others

A workaround I have tried that seems to be effective, is to create a folder inside your source web application, add a web.config inside that folder with the rules pointing to the destination web application:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="ReverseProxyInboundRule1" stopProcessing="true">
                    <match url="(.*)" />
                    <action type="Rewrite" url="http://<<<TARGET_HOSTNAME>>>{R:1}" />
                    <serverVariables>
                        <set name="HTTP_X_ORIGINAL_ACCEPT_ENCODING" value="{HTTP_ACCEPT_ENCODING}" />
                        <set name="HTTP_ACCEPT_ENCODING" value="" />
                    </serverVariables>
                </rule>
            </rules>
            <outboundRules>
                <rule name="RestoreAcceptEncoding" preCondition="RestoreAcceptEncoding">
                    <match serverVariable="HTTP_ACCEPT_ENCODING" pattern="^(.*)$" />
                    <action type="Rewrite" value="{HTTP_X_ORIGINAL_ACCEPT_ENCODING}" />
                </rule>
                <preConditions>
                    <preCondition name="RestoreAcceptEncoding">
                        <add input="{HTTP_X_ORIGINAL_ACCEPT_ENCODING}" pattern=".*" />
                    </preCondition>
                </preConditions>
            </outboundRules>
        </rewrite>
    </system.webServer>
</configuration>

Also added instructions from https://blogs.msdn.microsoft.com/friis/2016/08/25/iis-with-url-rewrite-as-a-reverse-proxy-part-2-dealing-with-500-52-status-codes/ around GZIP

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