How to disable all traffic through iptables?

Question

linux

How to completely disable all incoming and outgoing traffic through iptables?
And how to check that nothing is siphoning?
The task is to disable everything and allow only receiving and sending traffic through vpn.
Who can help with the task? (not for free)

Answer 1

iptables -F INPUT
iptables -P INPUT DROP

iptables -F OUTPUT
iptables -P OUTPUT DROP

well, then add rules for connecting to the VPN and for traffic in the VPN itself