Question

I have a website set up with nginx acting as a reverse proxy to apache 2.2, which is running php. From apache and php’s perspective the IP address of all requests is the nginx server. I’d like php to see the same remote IP that nginx sees.

Nginx sets a header X-Real-IP which contains the remote IP that nginx sees. I tried doing something like this in the apache conf:

SetEnvIf ^X-Real-IP$ "(.+)" REMOTE_ADDR=$1

My hope was that I could set the REMOTE_ADDR environment variable and when php finally gets invoked, it would see the remote IP that nginx sees. I think the php code is doing this:

$_SERVER['REMOTE_ADDR']

Anyway, this isn’t working. Can you not set REMOTE_ADDR in the apache config file?

Answer 1

Not sure whether REMOTE_ADDR can be changed that way…

Actually, you might need to install / enable another Apache module, like mod_rpaf (quoting) :

It changes the remote address of the
client visible to other Apache modules
when two conditions are satisfied.

First condition is that the remote
client is actually a proxy that is
defined in httpd.conf.
Secondly if
there is an incoming X-Forwarded-For
header and the proxy is in it’s list
of known proxies it takes the last IP
from the incoming X-Forwarded-For
header and changes the remote address
of the client in the request
structure.
It also takes the
incoming X-Host header and updates the
virtualhost settings accordingly.

For Apache2 mod_proxy it takes the
X-Forwared-Host header and updates the
virtualhosts

Here’s a blog-post about that : Nginx proxy to Apache – access remote host IP address using mod_praf

Update: original link not working right now, but it is available also as a debian package: apt-get install libapache2-mod-rpaf