[users@httpd] reverse proxy client certificat pass through

["Guenther, Christian" <Ch...@realtech.com>]

Hi List,

I have an application server in an internal DMZ for which I use an Apache2 as a reverse proxy. The overall communication works flawlessly. Clients connect to the Apache and it passes the communication requests through to my internal application server - by the way it is an SAP XI.

Now I added SSL to my setup and this too works perfectly. A client uses SSL to contact the application server. The Apache as reverse proxy terminates the SSL connection and then connects to the internal application server via SSL.

But now I want the external client to authenticate itself to the application server via client certificate and this won't work at all. I mean as I see it in normal SSL communication the client certificate is taken by the apache wich will not use it because he is not configured to check for client certificates. The application server again is supposed to authenticate the client via its certificate which fails because the Apache does not pass the certificate through to him. 

Is there any way of configuring the apache to terminate the SSL connection but pass the client certificate from the outside client to the internal application server??? 

Thanks in advance,

   Christian

Ps.: I have added my httpd.conf part that deals with the XI backend


<VirtualHost 172.30.210.210>
    ServerName web004.externerhost.de
    ServerAdmin webmaster@externerhost.de
    # This virtual host does not serve any documents itself but only proxy

    ProxyRequests Off
    ProxyPreserveHost On
    RequestHeader set ClientProtocol HTTPS

    # Set additional header for letting IE 6 SP2 accept 3rd party cookies
    # in an iframe. See: http://msdn.microsoft.com/library/default.asp?url=
    # /workshop/security/privacy/privacy_ovw_entry.asp for details
    Header add P3P CP="NOI"

    SSLEngine On
    SSLCertificateFile /etc/apache2/ssl.crt/web004_cert.pem
    SSLCertificateKeyFile /etc/apache2/ssl.key/web004_key.pem
    SSLProxyEngine On

    # Forward all requests for this host to SAP XI
    ProxyPass /		https://ux210210.internerhost.lan:8007/

    # Rewrite HTTP 302 object moved redirects from SAP XI
    ProxyPassReverse /  https://ux210210.internerhost.lan:8007/
</VirtualHost>


Christian Günther
SAP Technical Consultant

REALTECH

REALTECH system consulting GmbH
Industriestraße 39c
69190 Walldorf
Germany

Tel.: +49.6227.837.267
Mobile: +49.173.2571.326
Fax:+49.6227.837.837
mailto:christian.guenther@realtech.com

Re: [users@httpd] reverse proxy client certificat pass through

[allan juul <al...@muly.dk>]

Guenther, Christian wrote:
> Hi List,
> 
> I have an application server in an internal DMZ for which I use an Apache2 as a reverse proxy. The overall communication works flawlessly. Clients connect to the Apache and it passes the communication requests through to my internal application server - by the way it is an SAP XI.
> 
> Now I added SSL to my setup and this too works perfectly. A client uses SSL to contact the application server. The Apache as reverse proxy terminates the SSL connection and then connects to the internal application server via SSL.
> 
> But now I want the external client to authenticate itself to the application server via client certificate and this won't work at all. I mean as I see it in normal SSL communication the client certificate is taken by the apache wich will not use it because he is not configured to check for client certificates. The application server again is supposed to authenticate the client via its certificate which fails because the Apache does not pass the certificate through to him. 
> 
> Is there any way of configuring the apache to terminate the SSL connection but pass the client certificate from the outside client to the internal application server??? 
> 
> Thanks in advance,
> 
>    Christian
> 
> Ps.: I have added my httpd.conf part that deals with the XI backend
> 
> 
> <VirtualHost 172.30.210.210>
>     ServerName web004.externerhost.de
>     ServerAdmin webmaster@externerhost.de
>     # This virtual host does not serve any documents itself but only proxy
> 
>     ProxyRequests Off
>     ProxyPreserveHost On
>     RequestHeader set ClientProtocol HTTPS
> 
>     # Set additional header for letting IE 6 SP2 accept 3rd party cookies
>     # in an iframe. See: http://msdn.microsoft.com/library/default.asp?url=
>     # /workshop/security/privacy/privacy_ovw_entry.asp for details
>     Header add P3P CP="NOI"
> 
>     SSLEngine On
>     SSLCertificateFile /etc/apache2/ssl.crt/web004_cert.pem
>     SSLCertificateKeyFile /etc/apache2/ssl.key/web004_key.pem
>     SSLProxyEngine On
> 
>     # Forward all requests for this host to SAP XI
>     ProxyPass /		https://ux210210.internerhost.lan:8007/
> 
>     # Rewrite HTTP 302 object moved redirects from SAP XI
>     ProxyPassReverse /  https://ux210210.internerhost.lan:8007/
> </VirtualHost>
>

if you don't have the frontend apache configured to check for client 
certificates i don't see how you can pass the certificates to the 
application server.

it sounds as if you will need a "double" verification - one from the 
frontend and one from the backend.

we have a setup where we pass the certificate (escaped) to the proxied 
server as a RequestHeader (we use mod_rewrite). the verification then 
happens at the frontend and the communication (in our case) between 
frontend and backend is http, not https.

./allan

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