Fascinatingly effective, but maybe I'm the only one getting the heebie-jeebies when someone suggests implementing this in production corp networks. Sure it's super convenient, but the thought of bypassing all traditional NATs and firewalls, and instead relying solely on a software ACL, seems super risky. Maybe I just don't understand how it works, but it seems that a bad actor getting access to a stray VM with Tailscale on it in, say, your AWS testing env, essentially has an clear path all the way into your laptop on the internal corp network, through the kernel, into user space and into the Tailscale ACL code as the sole arbiter of granting or blocking access. Would I even know someone unauthorized made it that far?
It's no different from traditional VPNs. The tailnet admin has control over the routes that are exposed to clients and ACLs are available to further limit access. It's an overlay network, it doesn't magically give you access to user space on people's laptops.