Does SPN has a “Kill Switch”?
SPN does not need a Kill Switch! It really doesn't.
Here is the how and why:
A Kill Switch blocks all internet connections to stop data leakage via the network in the event of a dropped VPN connection.
VPNs are indifferent to the connections running through them, they are basically a dumb pipe.
Because they don’t know what is running through them, they don’t know when something is bypassing it, or in other words: leaking.
When SPN is activated, Portmaster terminates/“destroys” all internet traffic locally. No TCP/UDP connection is established locally to the desired service. Instead a new TCP/UDP connection is created by the exit node to the destination.
So in case of Internet hiccups or node issues the connection is broken, but nothing can be leaked, because there is no “actual” connection.
While VPNs are only a pipe traffic goes through, SPN beams your traffic across the globe, nothing can leak in this beaming process.
Because Portmaster is a firewall, it is always in full control of all your connections.
If the connection to SPN breaks, Portmaster simply halts all connections until you are safely connected again. There is no race condition as with VPN kill switches.