As you can imagine we did quite a bit of research with our existing users/customers while working on the design of Boundary. One thing we heard almost universally was "please don't require us to install another agent on our boxes". So we decided to focus initially on transparent use cases that only require running additional nodes (Boundary controller/worker) without requiring additional software to be installed/secured/maintained on your end hosts.

> the endpoint can be closed off to incoming connections from the internet, and you don't need to maintain various firewall whitelist

If you think about this a bit differently, a Boundary worker is also acting as a reverse proxy gating access to your non-public network resources. You can definitely use Boundary right now to take resources you have on the public Internet, put them in a private-only subnet or security group, and then use a Boundary worker to gate access. It's simply a reverse proxy running on a different host rather than one running on the end host. You wouldn't _need_ to add a firewall to ensure that only Boundary workers can make incoming calls to the end hosts, it's simply defense in depth.