Identity and access
Zero trust
Granting nothing for being on the network: every request to every service is authenticated and authorized.
The perimeter model trusts whatever is inside the network (the castle and moat), so one foothold reaches everything. Zero trust treats the internal network like the internet: each service checks who is calling (a user's or device's identity, often a client certificate over mTLS) and whether they may, on every request, by its own policy. Reaching a port then gives an attacker nothing by itself. Real deployments add device health checks, short-lived credentials and a policy point (a proxy or service mesh) in front of every service; the cost is that identity becomes the thing to protect, since a stolen key passes every check.