Is there a way to remove apaches Reverse Proxy Request Headers? - apache

Question

When acting as a reverse proxy, apache adds x-forwarded headers as described here.
http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#x-headers
In my configuration I have configured server A as a forward proxy. There is a rule like this:
RewriteRule proxy:(.*example.com)/(.*) $1.mysecondserver.com/$2 [P]
This rule lets the server request the resource from one of my other servers.
On the second server (origin) I have a virtual host container for the resource and another rewrite rule like this:
RewriteRule some-regex some-url [P]
It may not seem to make sense like this but there is a lot of other stuff going on that I left out as it is not part of the problem.
However that final request has these headers:
[X-Forwarded-For] => ip of 1st server
[X-Forwarded-Host] => example.myseconserver.com
[X-Forwarded-Server] => example.com
I want those headers gone.
I seem to be unable to unset them with mod_headers. I can add more entries to them, but I can not remove them.
Any ideas?

Answer 1

Since Apache 2, as this pretty answer says, the
ProxyAddHeaders Off
theoretically disables it. In my experiences, it had no effect. However, combined with
<Proxy *>
ProxyAddHeaders Off
</Proxy>
and, with
RequestHeader unset X-Forwarded-Host
RequestHeader unset X-Forwarded-For
RequestHeader unset X-Forwarded-Server
somewhere it started to work.

Answer 2

corrected answer: there is no way to do that since its hardcoded
to fix this in the source code of mod_proxy_http.c search for the following part:
apr_table_mergen(r->headers_in, "X-Forwarded-Server",
r->server->server_hostname);
}
and immediately after that add this code:
// remove any X-Forwarded headers
apr_table_unset(r->headers_in, "X-Forwarded-For");
apr_table_unset(r->headers_in, "X-Forwarded-Host");
apr_table_unset(r->headers_in, "X-Forwarded-Server");
then compile by running apxs2 -cia mod_proxy_http.c

Answer 3

I had the same problem on httpd 2.2 on CentOS 5. Installing httpd 2.4 wasn't possible. But because of some reasons I couldn't switch to nginx completly. So I did it by inserting nginx proxy between httpd and the destination address. So I had: httpd(localhost:80/path) -> nginx(localhost:81/path) -> http://your.destination/path. Installation steps are the following:
Install nginx according to these instructions
Configure nginx to avoid security problems.
Add an location in nginx that will remove those httpd's reverse proxy request headers. It can look like this:
location /path {
proxy_set_header x-forwarded-for "";
proxy_set_header x-forwarded-host "";
proxy_set_header x-forwarded-server "";
proxy_pass http://your.destination/path;
}