How to send traffic through the program?

Question

Computer networks

Network topology:
1. There is the first computer on windows 10, it acts as a router, it has two network cards, the first one comes from the Internet provider, and the second one goes to the local area.
2. Other computers are connected to this LAN.
On the first computer, special self-written software is installed - a proxy server, in theory, all traffic should pass through it in order to control the local area, block something and allow something, and it partly does this.
If you use a browser on the first computer, then all the rules work (for example, the prohibition of entering vk.com from the workplace), but from other computers in the local area at this moment you can safely go to vk.com, the ban does not occur.
But, if on a computer that is in LAN, register the address of the first computer as a proxy server (in the properties of the browser), then all the rules begin to work on a computer from LAN. Question: what should be done to make these rules work without
specifying a proxy server in the browser properties of each computer? How to force a proxy server to process all traffic passing from one network card to another?

Answer 1

Google for transparent proxy.

Answer 2

what needs to be done to make these rules work without
prescribing a proxy server in the browser properties of each computer?

Assign a computer with a proxy server as the default gateway, then all traffic will go to it.
Just distribute the necessary settings via DHCP, where the desired server is specified by the gateway.

Answer 3

The options are as follows:
1. Redirect all types of traffic you need (important - and supported by your proxy server) to the port of the proxy server (transparent proxy mentioned above).
2. Automatic configuration of browsers through the autoconfiguration script (google according to WPAD PAC).
You also need to understand how you will deliver these settings to clients - for example, through GPO or through DHCP.