17 ‐ Can We Use One WAF Before the Load Balancer Instead of Having WAF in Each VCN? - SanjeevOCI/Study GitHub Wiki

Can We Use One WAF Before the Load Balancer Instead of Having WAF in Each VCN?

Yes, you can use one centralized WAF (Web Application Firewall) before the load balancer instead of deploying a WAF in each VCN. However, the choice depends on your architecture, security requirements, and traffic flow. Here's a comparison to help decide which is better:

1. Centralized WAF Before the Load Balancer

  • Setup:

    • Deploy a single WAF in front of the load balancer.
    • All incoming traffic is inspected by the WAF before being routed to the backend services.

  • Advantages:

    1. Cost-Effective:
      • Reduces costs by eliminating the need for multiple WAF instances in each VCN.
    2. Simplified Management:
      • Centralized rule management and monitoring for all traffic.
    3. Consistent Security:
      • Ensures uniform security policies across all backend services.

  • Disadvantages:

    1. Single Point of Failure:
      • If the centralized WAF fails, it could disrupt traffic to all backend services.
    2. Latency:
      • All traffic must pass through the centralized WAF, potentially adding latency.
    3. Scalability:
      • May become a bottleneck if traffic grows significantly.

2. WAF in Each VCN

  • Setup:

    • Deploy a WAF in front of each VCN or application-specific load balancer.

  • Advantages:

    1. Distributed Security:
      • Each VCN has its own WAF, reducing dependency on a single WAF.
    2. Custom Policies:
      • Allows application-specific WAF rules tailored to individual VCNs or services.
    3. Scalability:
      • Each WAF scales independently with the VCN or application.

  • Disadvantages:

    1. Higher Costs:
      • Requires multiple WAF instances, increasing operational costs.
    2. Complex Management:
      • Managing WAF rules across multiple VCNs can be challenging.
    3. Inconsistent Policies:
      • Risk of inconsistent security policies if not managed centrally.

Which is Better?

  • Centralized WAF:

    • Best for simpler architectures with multiple applications sharing a common security policy.
    • Suitable for cost-sensitive environments where minimizing WAF instances is a priority.

  • WAF in Each VCN:

    • Best for complex architectures with application-specific security needs.
    • Suitable for highly distributed environments where each VCN or application requires independent security policies.

Recommendation

  • Start with a centralized WAF if:

    • Your architecture is simple, and applications share similar security requirements.
    • You want to reduce costs and simplify management.

  • Use WAF in each VCN if:

    • You have different security requirements for each application or VCN.
    • You need high availability and want to avoid a single point of failure.

In most cases, a centralized WAF before the load balancer is sufficient for general use cases, but distributed WAFs are better for complex, large-scale architectures.