I'm running an ubuntu jaunty server with 2 network interfaces configured: one public IP, one private. When I request the server IP I get the public IP. If I've got multiple interfaces is there a best practice for assuring I'm getting the public one (which is what I want)?
<?php
echo " <table>";
echo "<tr><td>" .$_SERVER['SERVER_ADDR'] ."</td><td>SERVER_ADDR</td></tr>";
echo "<tr><td>" .$_SERVER['SERVER_NAME'] ."</td><td>SERVER_NAME</td></tr>";
echo " </table>";
?>
I think this is handled by Apache when you set up your domains. Apache recommends using a separate daemon per ip to keep them straight: http://httpd.apache.org/docs/1.3/vhosts/ip-based.html
Create a separate httpd installation for each virtual host. For each installation, use the Listen directive in the configuration file to select which IP address (or virtual host) that daemon services. e.g.
`Listen www.smallco.com:80`It is recommended that you use an IP address instead of a hostname (see DNS caveats).
OR
You could probably use your /etc/hosts file to ensure that the hostname you choose always resolves to the desired ip. See: http://www.faqs.org/docs/securing/chap9sec95.html for info on /etc/hosts.
My impression is that you'll get the address of wherever the traffic is coming in from, so if you want to always act with regard to the public interface regardless of where your request came from, you'll have to disregard $_SERVER['SERVER_ADDR'] and determine the IP you want to deal with in code (hardcoding it, analyzing the interface table and looking for something that isn't on a private network, what-have-you).
You should always get the public IP from the public and the private IP from the people in your private network. There is no sane way of assuring you'll always get the public IP nor it makes sense to