External Client should use our proxy to get filtered by our firewall

Question

I would like an external client (4.3.2.1) to use our proxy (9.9.9.9) which forwards traffic to our firewall (8.8.8.8) which then forwards the traffic back to our client (4.3.2.1).

So I'm curious if:

1. This is possible
2. squid the best choice
3. There a quick and dirty guide available
4. The proxy needs to sit in front of or behind the firewall

I've done quite a bit of research and see a proxy used in various ways, but not in the way that I want to use it.

Answer 1

I figured it out. It all depends on where I put the proxy. So using Squid, I put it in our DMZ and then told the firewall to use our normal user filters and it is now making requests "as a user" through the firewall.