[tproxy] Is tproxy a real transparent proxy?

[mtpr]

I am testing tproxy with a vmware Centos-5.3 virtual server.
I installed squid-3.1, iptables-1.4.3 and kernel-2.6.28.3.
Everything seems to be working, unless one...
There is a proxy behaviour I thought it would be expectable, but I found 
it doesn't work the way I thought.

Here is the example:
If I create a cgi-bin script in a apache webserver that prints the 
client ip address like this one:

#!/bin/env python
# coding: utf-8
import os

print 'Content-Type: text/plain'
print
print os.environ['REMOTE_ADDR']

I thought that, in a real transparent proxy, it would give me the 
original client ip address of the browser computer.
But no!
Like the old transparent proxy way (not tproxy), it prints the ip 
address of the proxy server.
If I want the original ip address, I need to read the environment 
variable HTTP_X_FORWARDED_FOR.
It doesn't seem to be a "real" transparent proxy.

Is this the expectable behaviour, or could be something wrong with the 
way I setup my tproxy?


mtpr