Can I share my internet connection and redirect clients to my web server?
If you really want to configure your network in such a way,
here are a few bricks I'd advise to start with:


Install Squid version 3 and configure it in transparent
mode. You may use MacPorts to build, configure and install it.
With MacPorts you would do it with: port install squid3.
Install Apache. With the same Macports, you would have to
do it with: port install apache2.


You will find many documents on the web to help to build this, but I didn't find any one complete and good enough to recommand it.