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From Stefan Eissing <>
Subject Re: how make backend applications aware about tls-offloading
Date Sun, 08 Jan 2017 10:01:11 GMT
There is the reverse situation which is called opportunistic encryption, namely the transfer
of a http: request over a TLS connection.

Both cases are tricky on HTTP/1.x because the URI scheme is not transported in requests (commonly.
the spec would allow it but no one does it, so no one is prepared to honor/handle it). HTTP/2,
with opportunistic encryption in mind, added the ":scheme" header for this. But implementation
is also tricky.

So, mod_http2 has similar problems to this ATS setup: convincing the request processing parts
in the server that a request has a certain scheme, *independent* of mod_ssl's presence. I
think it would be nice if we could fix this.

One approach that comes to mind:
 * add the uri scheme to request_rec->scheme
 * set it by:
   1. parse the request uri
   2. if not set, fix it in very late read hooks to "http:"
   3. have mod_ssl install an earlier hook that sets "https:" if not present
 * check that URI host and Host: header are an allowed combination
 * check that r->scheme and r->server are an allowed combination

ATS would then be configured to forward requests to the httpd backend by using absolute request
uris (so they carry the scheme) or HTTP/2. httpd would be configured to accept https: uris
from ATS remote ip.

And while there are numerous parts/applications where the wheels fall off in such a setup,
it is not the default setup. No one initially needs to be able to get it right. But in a concrete
deployment, the configuration can be made and the application code fixed where necessary.


> Am 07.01.2017 um 09:30 schrieb Reindl Harald <>:
> * Apache Trafficserver in front
> * ATS configured for TLS-offloading
> * connection to backend-httpd on the LAN unencrypted
> * mod_remoteip correctly configured on backend httpd
> is there any way to make the backend php application aware that in fact $_SERVER['HTTPS']
and $_SERVER['REQUEST_SCHEME'] should be 'on' / https:// in case of generate absolute URLs
like for emails
> in a perfect world this would be handeled like the transparent translation of the client
IP with and it's RemoteIPInternalProxy
and a header like "X-Forwarded-TLS"
> something like below where "X-TLS-Offloading" is only evaluated from "RemoteIPInternalProxy"
pyhsical addressess
> RemoteIPHeader         X-Forwarded-For
> RemoteTLSHeader        X-TLS-Offloading
> RemoteIPInternalProxy

Stefan Eissing

<green/>bytes GmbH
Hafenstrasse 16
48155 M√ľnster

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