Trust inside the network.
WHAT THE OLD ASSUMPTION WAS
Inside the network is safe.
WHY IT NO LONGER HOLDS
One compromised component otherwise reaches everything.
WHAT TO IMPLEMENT
Authentication between services Authorisation for what each may do Encryption in transit
WHAT SERVICE AUTHENTICATION USUALLY USES
Mutual certificates, or short-lived tokens issued centrally.
WHAT SHORT-LIVED MEANS
Minutes or hours, renewed automatically.
WHY
A leaked credential expires quickly.
WHAT TO AVOID
Long-lived shared secrets in configuration files One credential used by every service
WHY
It removes any ability to limit or attribute.
WHAT TO SCOPE
Each service to the specific calls it needs.
WHAT TO LOG
Every inter-service call, with the correlation identifier.
WHAT TO MONITOR
Calls that should not be happening.
WHY
They indicate either a defect or a compromise.
WHAT TO RESTRICT AT THE NETWORK LEVEL
Which services may reach which.
WHY BOTH NETWORK AND APPLICATION CONTROLS
Either alone fails eventually.
WHAT TO ROTATE
Everything, automatically.
WHAT TO TEST
That a service cannot call what it should not.
