Sunday, July 28, 2013

Fixing the client IP as perceived by Apache behind Nginx reverse proxy

In my recent post Using Nginx to reverse proxy a secure apache site that is using socket.io/node.js/websockets I found that I was only getting the proxy's IP address in all of my apache logs as well as in the application tracking. This does make sense since from Apache's perspective the proxy is the actual client and not the real remote client. I found however that it was possible to get around this. Apparently there are several Apache modules that can do this, however I did not want to build from sources if I could avoid it. So I choose the one that was already available in the EPEL repository.

I already had the EPEL repository registered on the server but for those that does not you can use the following commands to register it.
rpm -Uvh http://ftp.crc.dk/fedora-epel/6/i386/epel-release-6-8.noarch.rpm
Now install the module
yum install mod_extract_forwarded
After installing the module you need to register an allowed forwarder (ie. the IP of your proxy). In all my logs the ip 127.0.0.1 was registered as the client of every request so adding that did the trick.
echo "MEFaccept 127.0.0.1" >> /etc/httpd/conf.d/mod_extract_forwarded.conf
service httpd restart
Recheck your webserver/application logs, this worked for me.
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