How to block WiFi traffic without VPN on Mac OS?

Question

VPN

Hello!
Once I encountered e-mail withdrawal (attempts) after using open networks, because I use a mail program and many different mail servers, etc.
I decided to take care of security on MacOS when using open Wifi (on vacation, hotels).
But if the VPN breaks or before the VPN is loaded, the traffic goes merrily, authorizations go through all sorts of services, etc., which is very frustrating.
I even downloaded Kaspersky VPN, but to no avail, when the system breaks or starts, everything goes through the network.
Is there a neat tool or app for the latest macOS?
Thank you!

Answer 1

Use mail services that work only through encrypted channels (imaps, smtps) or use the web interfaces of mail services (and almost everyone has them) with https and control browser messages, this will be enough.
ps so that after the vpn is broken, all communication does not go open, configure the connection to each provider (wifi) manually, removing the gateway and registering it manually via route add exclusively for your vpn servers
I recommend using a proxy instead of vpn, its settings are easier to control (for example, in the firefox browser this is done with a simple extension), for example, by buying any cheapest vps (you need ssh access), and without making any settings, just start the ssh client connection with the redirect option ports (-D1080) - this will raise a local socks proxy that is understood by almost all programs and browsers.
and if you set up passwordless authentication for ssh, these are 2-3 commands, they are easy to google, and then start the connection in an endless loop like this:

@echo off
:loop
ssh имя@сервер -p порт -D1080 -N
goto :loop

then your proxy will rise automatically when you reconnect and will be turned off if there is no Internet or the vps service is unavailable and your browser will not try to connect via an insecure channel.