ELI5: What is East-west traffic control?

Once someone is inside a building, you still want to make sure they cannot wander into every room. East-west traffic control is about watching and limiting movement between rooms (systems) that are already inside the same network.

Definition

East-west traffic control refers to the security monitoring and restriction of traffic flowing laterally between systems within the same network, as opposed to north-south traffic that crosses the network perimeter. Once attackers breach the perimeter, they often move laterally between internal systems to expand access — proper east-west controls limit this lateral movement.

Key Details

  • Traditional perimeter firewalls focus on north-south traffic; east-west often flows freely internally
  • Micro-segmentation creates internal boundaries that restrict lateral movement
  • Zero trust principles require authentication and authorization even for internal east-west traffic
  • Network monitoring of east-west traffic is often limited — many organizations have poor internal visibility
  • Attackers rely on unrestricted east-west traffic for lateral movement and propagation

Connections