Retail Chain Segmentation and PCI Compliance
A national retail chain with 500 stores needs to comply with PCI DSS 4.0. Each store has a local network with point-of-sale (POS) terminals, back-office computers, IP cameras, and guest Wi-Fi. The current network is flat: all devices are on the same VLAN and subnet, with a single firewall at the store edge connecting to the corporate WAN. The chain is implementing a new segmentation strategy to isolate POS traffic from other traffic. They plan to use VLANs and ACLs on the store switches, but the switches are older and have limited ACL capacity. The company also wants to centralize management and policy enforcement across all stores using a software-defined approach. They are considering Aruba ClearPass for network access control and Aruba Central for management. The WAN is MPLS-based with 50 Mbps links per store. The POS terminals run a legacy Windows OS that cannot be patched. The company also has a cloud-based payment gateway that POS terminals access over the internet. The security team requires that all POS traffic be encrypted and that any compromised POS cannot communicate laterally with other devices. The company has a small IT staff and needs a solution that is easy to deploy and manage.
1. Design a segmentation strategy for the stores that meets PCI DSS requirements while accommodating the legacy POS terminals and limited switch capabilities.
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Given the flat network and limited switch ACLs, a defense-in-depth approach is needed. 1) Use VLANs to separate POS, back-office, cameras, and guest Wi-Fi. Even with limited ACLs, basic inter-VLAN routing can be controlled at the gateway. 2) Implement a next-generation firewall (NGFW) at each store edge (or use a centralized firewall in the data center with tunneling) to enforce policies between VLANs and to the internet. 3) For POS terminals, place them in a dedicated VLAN with strict inbound/outbound rules: only allow communication to the payment gateway IPs and necessary internal servers (e.g., POS management). Deny all other traffic. 4) Use Aruba ClearPass for NAC: profile devices, ensure only authorized POS devices connect, and assign them to the POS VLAN dynamically. ClearPass can also enforce posture checks. 5) For encryption, use IPsec or TLS from POS to payment gateway; if the legacy OS supports only older protocols, consider a local encryption gateway or upgrade path. 6) To prevent lateral movement, implement micro-segmentation using host-based firewalls on POS (if possible) or use ClearPass to enforce role-based access. 7) Centralize management with Aruba Central to push consistent policies across all stores. 8) For the WAN, use encrypted tunnels (e.g., IPsec) for POS traffic to the data center. 9) Regularly audit and monitor with ClearPass and Central analytics.
2. How would you address the limited ACL capacity on the store switches and the need for centralized policy enforcement?
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Limited ACL capacity means we cannot rely solely on switch ACLs. Options: 1) Offload enforcement to the store edge firewall or a centralized firewall via tunneling (e.g., using GRE or IPsec to a regional hub). 2) Use Aruba ClearPass to dynamically assign VLANs and download roles to switches that support it (e.g., using RADIUS attributes). If switches support only basic ACLs, use ClearPass to assign a VLAN per device type and rely on the firewall for inter-VLAN policies. 3) Consider upgrading switches in a phased manner, prioritizing stores with high traffic. 4) For centralized management, use Aruba Central to orchestrate configuration templates and push policies consistently. Central can also integrate with ClearPass for unified policy. 5) Implement a software-defined branch (SD-Branch) solution with Aruba gateways that provide advanced security features (firewall, IDS/IPS) at each store, reducing reliance on switch ACLs. 6) Use a zero-trust model: authenticate every device via 802.1X and enforce least privilege. This reduces the need for complex ACLs because only authorized devices get on the network.