How to deny outgoing connections to port 80 on PCs connected to a PPTPD based VPN in Ubuntu Server?

Question

linux

There is a server on Ubuntu Server on which pptpd is installed.
There is a PC on win7 that connects to a VPN server.
The task is to prohibit the connected PC from accessing the Internet on port 80.
Added a rule:
iptables -A OUTPUT -j REJECT -p tcp --dport 80
As a result, outgoing connections to port 80 were closed on the server, but not on the PC connected to this server.
Please tell me how this can be done.

Answer 1

Why did you add it to OUTPUT? This is the chain for outgoing from the server itself.
You need to add to FORWARD, and also specify the outgoing, for example, interface or address range, so as not to kill all transit traffic on port 80 at all.