Speaking of security mechanisms that even non-security folks will have some familiarity with, captive portals are a common network access control strategy. They're the walls you encounter when trying to get online in a hotel or an airplane; everything you try to access takes you to a specially configured login screen. You will receive credentials from an administrator, or you will submit a payment – either way, after you've authenticated, the captive portal will grant access via some means (a common one is SNMP management post-authentication).
I know what the hacker in you is saying: When the unauthenticated client tries to send an HTTP request, they get a 301 redirect to ...
