Proxy Server

Dear community,
since I am a german guy, excuse gramatical mistakes.

I create a proxy to hide my application servers public IP from my customers.
I am actually using those 3 lines
(for testing reasons I am forwarding the traffic which connects to the ubuntu proxy to my apache webserver (5.196.130.245:80)

Code:

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 5.196.130.245:80
iptables -t nat -A POSTROUTING -j MASQUERADE

I show this to a friend/competitor and he said, lol, with this code ur "hiding" the costumers IP in ur Database logs
(for example, they use the register formular on the website username, password registerIP - and with my 3 lines of code the register IP is the proxys IP in every single case but he told me he got a way to see even the real Users IP, even if they connecting through the proxy)

So he sent me the following Picture of his script


Any1 knows / is able to describe me what he has done better / other than me? I cannot see any routing cmds in his script.

I'm now almost searching 5 days for a solution and this is my last hope to find it.


EDIT: okay, I just found out that this Script for setting up the iptables is not for forwarding any traffic.
For the redirecting/forwarding part he is using HAPROXY.

regards,
Julian