Network Firewall Policy: A Deep Dive in AWS Resources & Best Practices to Adopt
The modern enterprise network has evolved far beyond simple perimeter-based security models. According to recent Gartner research, 75% of organizations now operate in hybrid or multi-cloud environments, creating complex network architectures that traditional firewalls struggle to protect effectively. AWS Network Firewall Policy addresses this challenge by providing centralized, stateful network security controls that can protect VPCs at scale.
The stakes couldn't be higher. IBM's 2024 Cost of a Data Breach Report found that the average cost of a data breach reached $4.88 million, with network security failures being a primary attack vector. Yet many organizations still rely on fragmented security group rules scattered across hundreds of resources, creating blind spots that attackers readily exploit. Network Firewall Policy offers a solution by centralizing network security rules into manageable, auditable policies that can be consistently applied across your entire AWS infrastructure.
Real-world implementations demonstrate the power of this approach. Companies like Airbnb have successfully used AWS Network Firewall to protect their multi-tenant architecture, processing millions of connections daily while maintaining microsecond-level latency. Similarly, financial services organizations use Network Firewall Policy to meet strict compliance requirements while enabling secure communication between distributed applications. The network-firewall-rule-group component of these policies provides the granular control needed for enterprise-scale deployments.
In this blog post we will learn about what Network Firewall Policy is, how you can configure and work with it using Terraform, and learn about the best practices for this service.
What is Network Firewall Policy?
Network Firewall Policy is a comprehensive security management framework that defines how AWS Network Firewall inspects and filters network traffic within your VPC. It serves as the central configuration point where you specify the rules, actions, and behaviors that govern network traffic flow across your AWS infrastructure.
A Network Firewall Policy operates as a stateful firewall service that provides fine-grained control over network traffic at the subnet level. Unlike traditional security groups that operate at the instance level, Network Firewall Policy can inspect traffic patterns, perform deep packet inspection, and make decisions based on application-layer information. This capability makes it an ideal solution for organizations requiring advanced threat protection and compliance with strict security regulations.
The policy architecture consists of several key components working together to provide comprehensive network protection. At its core, the policy references multiple rule groups that contain the actual filtering logic. These network-firewall-rule-group components can be stateless or stateful, each serving different purposes in the traffic inspection process.
Policy Structure and Components
Network Firewall Policy follows a hierarchical structure that enables both flexibility and control. The policy itself acts as a container that references various rule groups and defines default actions for traffic that doesn't match any specific rules. This design allows for modular security configurations where common rules can be shared across multiple policies while maintaining the ability to customize behavior for specific use cases.
The policy evaluation process follows a specific order that ensures consistent and predictable behavior. First, stateless rule groups are evaluated in priority order, processing packets without considering connection state. These rules are ideal for basic filtering tasks like allowing or denying traffic based on source/destination IP addresses, ports, and protocols. If a packet passes through the stateless evaluation, it then proceeds to stateful rule groups.
Stateful rule groups provide more sophisticated traffic analysis by maintaining connection state information. They can track TCP connections, monitor application-layer protocols, and apply rules based on the context of the communication session. This capability is particularly valuable for detecting and preventing advanced threats that might use legitimate protocols for malicious purposes.
The policy also defines default actions that determine what happens to traffic that doesn't match any rules in the associated rule groups. These actions can be configured to drop, pass, or alert on unmatched traffic, providing a baseline security posture that aligns with your organization's risk tolerance.
Integration with VPC Architecture
Network Firewall Policy integrates seamlessly with your existing VPC architecture through a deployment model that doesn't require significant changes to your network design. The firewall endpoints are deployed in dedicated subnets within your VPC, and traffic is routed through these endpoints using standard VPC routing mechanisms.
This integration approach offers several advantages over traditional firewall deployments. First, it eliminates the need for complex network address translation (NAT) configurations that can introduce latency and complexity. Second, it maintains the native AWS networking capabilities, including support for features like VPC peering, Direct Connect, and Transit Gateway.
The policy can be associated with multiple firewall endpoints, enabling you to implement consistent security controls across different availability zones or even different VPCs. This scalability is particularly important for organizations with distributed architectures that need to maintain security consistency across their entire infrastructure.
The firewall endpoints themselves are managed AWS resources that automatically scale based on traffic volume. This means you don't need to worry about capacity planning or performance tuning - the service handles these operational aspects automatically while you focus on defining the security policies that protect your applications.
Strategic Network Security Management
Network Firewall Policy represents a strategic shift from reactive to proactive network security management. Traditional approaches often involve deploying multiple point solutions that create gaps in visibility and control. According to Ponemon Institute research, organizations using centralized security policy management reduce their average incident response time by 42% and decrease overall security costs by 23%.
The strategic value of Network Firewall Policy extends beyond simple traffic filtering. It provides a unified framework for implementing defense-in-depth strategies that can adapt to evolving threat landscapes. By centralizing policy definition and management, organizations can respond more quickly to security incidents and implement consistent controls across their entire infrastructure.
Centralized Policy Management
The centralized nature of Network Firewall Policy eliminates the complexity of managing hundreds of individual security group rules scattered across your infrastructure. Instead of maintaining separate configurations for each resource, you can define comprehensive policies that apply consistent security controls across multiple VPCs and accounts.
This centralization provides several key benefits. First, it simplifies compliance reporting by providing a single source of truth for network security policies. Auditors can review policy configurations and understand the complete security posture without examining individual resource configurations. Second, it enables consistent policy enforcement across different environments, ensuring that development, staging, and production environments maintain appropriate security boundaries.
The policy management capabilities also support version control and change management processes. You can track policy changes over time, roll back to previous versions when necessary, and implement approval workflows for policy modifications. This level of control is essential for organizations operating in regulated industries where security changes must be carefully documented and approved.
Regulatory Compliance Support
Network Firewall Policy provides robust support for regulatory compliance requirements across various industries. The service includes built-in capabilities for logging and monitoring that support compliance with standards like PCI DSS, HIPAA, and SOC 2. These capabilities include detailed traffic logs, rule evaluation logs, and alert notifications that provide the audit trail required for compliance reporting.
The policy framework also supports the implementation of network segmentation requirements that are common in compliance frameworks. You can define policies that isolate sensitive workloads, restrict access to specific resources, and monitor communication patterns between different security zones. This capability is particularly valuable for organizations processing sensitive data like payment card information or personal health records.
Additionally, the integration with AWS CloudTrail provides comprehensive audit logging of all policy changes and administrative actions. This audit trail includes information about who made changes, when they were made, and what specific modifications were implemented. This level of visibility is essential for demonstrating compliance with change management requirements and investigating security incidents.
Threat Intelligence Integration
Modern network security requires the ability to adapt quickly to emerging threats. Network Firewall Policy supports integration with threat intelligence feeds that can automatically update rules based on the latest threat information. This capability ensures that your network protection remains effective against new attack vectors without requiring manual policy updates.
The threat intelligence integration works through network-firewall-rule-group components that can reference external threat feeds. These feeds can include IP reputation lists, known malicious domains, and signature-based detection rules that identify specific attack patterns. The automatic updates ensure that your policies remain current with the latest threat landscape.
This integration approach also supports custom threat intelligence sources, allowing organizations to incorporate their own threat research and industry-specific intelligence feeds. This flexibility enables organizations to tailor their security posture to their specific risk profile and industry requirements.
Key Features and Capabilities
Stateful Traffic Inspection
Network Firewall Policy provides comprehensive stateful traffic inspection capabilities that go beyond simple packet filtering. The stateful engine maintains connection state information, allowing it to track TCP connections, monitor protocol conversations, and apply rules based on the context of network communications. This capability enables the detection of sophisticated attacks that might use legitimate protocols for malicious purposes.
The stateful inspection engine can analyze application-layer protocols, including HTTP, HTTPS, FTP, and SMTP. It can examine packet contents, match against regular expressions, and apply rules based on specific protocol behaviors. This deep inspection capability is particularly valuable for detecting data exfiltration attempts, command and control communications, and other advanced persistent threats.
Rule Group Architecture
The rule group architecture provides a flexible and scalable approach to policy management. Rule groups can be categorized as stateless or stateful, each serving different purposes in the traffic inspection process. Stateless rule groups process packets without considering connection state, making them ideal for basic filtering tasks and high-performance scenarios where minimal latency is critical.
Stateful rule groups provide more sophisticated analysis capabilities by maintaining connection state and application context. They can track communication sessions, apply rules based on protocol behaviors, and implement complex logic that considers the full context of network communications. This capability enables the implementation of advanced security controls that would be difficult or impossible to achieve with traditional security groups.
Flexible Action Framework
Network Firewall Policy supports a comprehensive set of actions that can be applied to traffic based on rule matches. These actions include allow, deny, drop, and alert, providing flexibility in how different types of traffic are handled. The alert action is particularly valuable for implementing monitoring and detection capabilities without disrupting legitimate traffic flows.
The action framework also supports custom actions that can trigger additional processing or notifications. For example, you can configure policies to generate detailed logs for specific types of traffic, send notifications to security teams when suspicious activity is detected, or integrate with other AWS services for automated incident response.
Multi-VPC and Cross-Account Support
Network Firewall Policy can be deployed across multiple VPCs and AWS accounts, providing consistent security controls across distributed architectures. This capability is essential for organizations with complex network topologies that span multiple accounts or regions. The cross-account support enables centralized policy management while maintaining the security boundaries required for multi-tenant environments.
The multi-VPC deployment model supports various architectural patterns, including hub-and-spoke topologies, mesh networks, and hybrid cloud configurations. This flexibility allows organizations to implement Network Firewall Policy in ways that align with their existing network architecture and operational requirements.
Integration Ecosystem
Network Firewall Policy integrates with a comprehensive ecosystem of AWS services that enhance its capabilities and provide additional value for enterprise deployments. The network-firewall-rule-group integration enables modular policy management, while connections to services like CloudWatch, S3, and KMS provide logging, monitoring, and encryption capabilities.
At the time of writing there are 15+ AWS services that integrate with Network Firewall Policy in some capacity. These integrations include CloudWatch for monitoring and alerting, S3 for log storage and analysis, and KMS for encryption of sensitive policy data and logs.
The integration with AWS Config enables continuous compliance monitoring by tracking policy changes and resource configurations. This capability provides automated compliance reporting and can trigger remediation actions when policy violations are detected. The integration with AWS Systems Manager supports automated policy deployment and management through infrastructure as code practices.
VPC integration enables seamless deployment within existing network architectures without requiring significant changes to routing or connectivity. The firewall endpoints integrate with VPC route tables, subnet configurations, and security group rules to provide comprehensive network protection that complements existing security controls.
Pricing and Scale Considerations
Network Firewall Policy follows a consumption-based pricing model that includes charges for firewall endpoints, data processing, and rule group evaluations. The pricing structure is designed to be cost-effective for organizations of all sizes, with charges scaling based on actual usage rather than fixed infrastructure costs.
The service includes several pricing components that organizations should consider when planning deployments. Firewall endpoint charges are based on the number of endpoints deployed and their uptime. Data processing charges are based on the volume of traffic processed by the firewall. Rule group evaluation charges are based on the number of rule groups associated with policies and the volume of traffic they process.
Scale Characteristics
Network Firewall Policy is designed to scale automatically based on traffic volume and processing requirements. The service can handle millions of connections per second and terabytes of data processing without manual intervention. This scalability is achieved through AWS's managed infrastructure that automatically provisions additional capacity when needed.
The scalability extends to rule group processing, where the service can evaluate thousands of rules per packet without introducing significant latency. This capability enables organizations to implement comprehensive security policies without compromising network performance. The scale characteristics also support burst traffic scenarios where traffic volume can increase rapidly due to application scaling or security events.
Enterprise Considerations
Enterprise deployments often require additional features and capabilities that go beyond basic network filtering. Network Firewall Policy supports enterprise requirements through advanced logging capabilities, integration with security information and event management (SIEM) systems, and support for regulatory compliance frameworks.
The enterprise feature set includes high availability deployment options that ensure continuous protection even during AWS service disruptions. The service supports cross-availability zone deployments that provide redundancy and fault tolerance. Additionally, the enterprise capabilities include priority support and professional services that can help organizations design and implement effective security policies.
For organizations requiring on-premises connectivity, Network Firewall Policy integrates with AWS Direct Connect and VPN services to provide consistent security controls across hybrid environments. However, for infrastructure running on AWS this is the most comprehensive and integrated solution available for centralized network security management.
The enterprise pricing model includes volume discounts for large-scale deployments and reserved capacity options that can reduce costs for predictable workloads. Organizations with significant traffic volumes can benefit from committed use discounts that provide cost savings in exchange for usage commitments.
Managing Network Firewall Policy using Terraform
Network Firewall Policy management through Terraform requires careful consideration of the service's hierarchical structure and dependencies. The Terraform configuration must account for the relationships between policies, rule groups, and firewall resources to ensure proper deployment order and resource dependencies.
Basic Policy Configuration
The fundamental Network Firewall Policy configuration establishes the foundational security framework for your VPC protection. This scenario demonstrates how to create a policy that provides essential network security controls while maintaining compatibility with existing infrastructure.
# Network Firewall Policy with comprehensive security controls
resource "aws_networkfirewall_firewall_policy" "main_security_policy" {
name = "main-security-policy-${var.environment}"
firewall_policy {
# Stateless rule group references for high-performance filtering
stateless_rule_group_reference {
priority = 100
resource_arn = aws_networkfirewall_rule_group.allow_outbound_https.arn
}
stateless_rule_group_reference {
priority = 200
resource_arn = aws_networkfirewall_rule_group.deny_malicious_ips.arn
}
# Stateful rule group references for connection-aware filtering
stateful_rule_group_reference {
priority = 300
resource_arn = aws_networkfirewall_rule_group.application_protocols.arn
}
stateful_rule_group_reference {
priority = 400
resource_arn = aws_networkfirewall_rule_group.threat_detection.arn
}
# Default actions for unmatched traffic
stateless_default_actions = ["aws:forward_to_sfe"]
stateless_fragment_default_actions = ["aws:forward_to_sfe"]
# Stateful engine configuration
stateful_engine_options {
rule_order = "DEFAULT_ACTION_ORDER"
}
# TLS inspection configuration for encrypted traffic
tls_inspection_configuration_arn = aws_networkfirewall_tls_inspection_configuration.main.arn
# Policy variables for dynamic rule configuration
policy_variables {
rule_variables {
key = "PROTECTED_NETWORKS"
ip_set {
definition = [
"10.0.0.0/8",
"172.16.0.0/12",
"192.168.0.0/16"
]
}
}
rule_variables {
key = "ALLOWED_PORTS"
port_set {
definition = ["80", "443", "8080", "8443"]
}
}
}
}
# Comprehensive tagging for resource management
tags = {
Name = "main-security-policy-${var.environment}"
Environment = var.environment
SecurityLevel = "high"
ComplianceRequired = "true"
ManagedBy = "terraform"
BusinessUnit = "security"
CostCenter = "security-operations"
LastUpdated = timestamp()
}
}
This configuration establishes a comprehensive security policy that references multiple rule groups with different priorities. The stateless rule groups handle high-performance filtering tasks, while stateful rule groups provide advanced threat detection capabilities. The policy variables enable dynamic rule configuration that can adapt to different network environments.
The dependency structure ensures that rule groups are created before the policy references them. The TLS inspection configuration enables encrypted traffic analysis, which is crucial for detecting threats that attempt to hide in encrypted communications. The tagging strategy supports both operational management and compliance reporting requirements.
Enterprise Multi-Environment Policy
Complex enterprise environments require sophisticated policy configurations that can support multiple environments while maintaining security boundaries. This scenario demonstrates how to create a policy framework
Managing Network Firewall Policy using Terraform
Managing Network Firewall Policy resources requires careful consideration of the security policies, rule groups, and configurations. Network Firewall Policies can be complex to manage due to their security-critical nature and the need to properly configure stateful and stateless rules.
Basic Network Firewall Policy with Stateless Rules
This example demonstrates creating a basic Network Firewall Policy with stateless rules for initial traffic filtering:
# Create a stateless rule group for basic traffic filtering
resource "aws_networkfirewall_rule_group" "basic_stateless_rules" {
name = "basic-stateless-filtering"
type = "STATELESS"
capacity = 100
description = "Basic stateless rules for traffic filtering"
rule_group {
rules_source {
stateless_rules_and_custom_actions {
stateless_rule {
priority = 100
rule_definition {
actions = ["aws:forward_to_sfe"]
match_attributes {
protocols = [6, 17] # TCP and UDP
source {
address_definition = "10.0.0.0/8"
}
destination {
address_definition = "172.16.0.0/16"
}
destination_port {
from_port = 80
to_port = 80
}
}
}
}
stateless_rule {
priority = 200
rule_definition {
actions = ["aws:drop"]
match_attributes {
protocols = [6] # TCP
source {
address_definition = "0.0.0.0/0"
}
destination_port {
from_port = 22
to_port = 22
}
}
}
}
}
}
}
tags = {
Name = "basic-stateless-rules"
Environment = "production"
Purpose = "traffic-filtering"
}
}
# Create the Network Firewall Policy
resource "aws_networkfirewall_firewall_policy" "main_policy" {
name = "main-firewall-policy"
description = "Main Network Firewall Policy with stateless rules"
firewall_policy {
# Default actions for stateless packet evaluation
stateless_default_actions = ["aws:forward_to_sfe"]
stateless_fragment_default_actions = ["aws:forward_to_sfe"]
# Reference to stateless rule groups
stateless_rule_group_reference {
priority = 100
resource_arn = aws_networkfirewall_rule_group.basic_stateless_rules.arn
}
# Default actions for stateful packet evaluation
stateful_default_actions = ["aws:drop_strict"]
# Stateful engine options
stateful_engine_options {
rule_order = "STRICT_ORDER"
}
}
tags = {
Name = "main-firewall-policy"
Environment = "production"
Purpose = "network-security"
ManagedBy = "terraform"
}
}
This configuration creates a basic Network Firewall Policy with stateless rules that forward legitimate traffic to the stateful firewall engine and drop unauthorized SSH connections.
Advanced Network Firewall Policy with Stateful Rules
For more sophisticated traffic inspection, you can create a Network Firewall Policy with stateful rules:
# Create a stateful rule group for application-aware filtering
resource "aws_networkfirewall_rule_group" "web_application_rules" {
name = "web-application-filtering"
type = "STATEFUL"
capacity = 200
description = "Stateful rules for web application security"
rule_group {
rule_variables {
ip_sets {
key = "WEBSERVERS"
ip_set {
definition = [
"10.0.1.0/24",
"10.0.2.0/24"
]
}
}
ip_sets {
key = "EXTERNAL_NETWORKS"
ip_set {
definition = [
"0.0.0.0/0"
]
}
}
port_sets {
key = "HTTP_PORTS"
port_set {
definition = ["80", "443", "8080", "8443"]
}
}
}
rules_source {
stateful_rule {
action = "PASS"
header {
destination = "$WEBSERVERS"
destination_port = "$HTTP_PORTS"
direction = "FORWARD"
protocol = "HTTP"
source = "$EXTERNAL_NETWORKS"
source_port = "ANY"
}
rule_option {
keyword = "sid"
settings = ["1"]
}
}
stateful_rule {
action = "DROP"
header {
destination = "$WEBSERVERS"
destination_port = "ANY"
direction = "FORWARD"
protocol = "TCP"
source = "$EXTERNAL_NETWORKS"
source_port = "ANY"
}
rule_option {
keyword = "sid"
settings = ["2"]
}
rule_option {
keyword = "msg"
settings = ["\\"Unauthorized access attempt\\""]
}
}
}
}
tags = {
Name = "web-application-rules"
Environment = "production"
Purpose = "application-security"
}
}
# Create a managed rule group reference for threat intelligence
resource "aws_networkfirewall_rule_group" "threat_intelligence" {
name = "threat-intelligence-rules"
type = "STATEFUL"
capacity = 500
description = "Threat intelligence based blocking rules"
rule_group {
rules_source {
rules_source_list {
generated_rules_type = "DENYLIST"
target_types = ["HTTP_HOST", "TLS_SNI"]
targets = [
"malicious-domain.com",
"suspicious-site.net",
"known-bad-actor.org"
]
}
}
}
tags = {
Name = "threat-intelligence-rules"
Environment = "production"
Purpose = "threat-blocking"
}
}
# Create the advanced Network Firewall Policy
resource "aws_networkfirewall_firewall_policy" "advanced_security_policy" {
name = "advanced-security-policy"
description = "Advanced Network Firewall Policy with comprehensive security rules"
firewall_policy {
# Stateless configuration
stateless_default_actions = ["aws:forward_to_sfe"]
stateless_fragment_default_actions = ["aws:forward_to_sfe"]
# Stateful configuration with custom actions
stateful_default_actions = ["aws:drop_strict"]
# Stateful rule group references
stateful_rule_group_reference {
priority = 100
resource_arn = aws_networkfirewall_rule_group.web_application_rules.arn
}
stateful_rule_group_reference {
priority = 200
resource_arn = aws_networkfirewall_rule_group.threat_intelligence.arn
}
# Stateful engine options for optimal performance
stateful_engine_options {
rule_order = "STRICT_ORDER"
stream_exception_policy = "CONTINUE"
}
# Custom actions for enhanced logging
policy_variables {
rule_variables {
ip_sets {
key = "CRITICAL_ASSETS"
ip_set {
definition = [
"10.0.10.0/24",
"10.0.11.0/24"
]
}
}
}
}
}
# Encryption configuration for policy data
encryption_configuration {
type = "CUSTOMER_KMS"
key_id = aws_kms_key.firewall_policy_key.arn
}
tags = {
Name = "advanced-security-policy"
Environment = "production"
SecurityLevel = "high"
ComplianceReq = "required"
ManagedBy = "terraform"
}
}
# KMS key for firewall policy encryption
resource "aws_kms_key" "firewall_policy_key" {
description = "KMS key for Network Firewall Policy encryption"
deletion_window_in_days = 7
enable_key_rotation = true
policy = jsonencode({
Version = "2012-10-17"
Statement = [
{
Sid = "Enable IAM User Permissions"
Effect = "Allow"
Principal = {
AWS = "arn:aws:iam::${data.aws_caller_identity.current.account_id}:root"
}
Action = "kms:*"
Resource = "*"
},
{
Sid = "Allow Network Firewall Service"
Effect = "Allow"
Principal = {
Service = "network-firewall.amazonaws.com"
}
Action = [
"kms:Decrypt",
"kms:DescribeKey"
]
Resource = "*"
}
]
})
tags = {
Name = "firewall-policy-key"
Environment = "production"
Purpose = "encryption"
}
}
resource "aws_kms_alias" "firewall_policy_key_alias" {
name = "alias/firewall-policy-key"
target_key_id = aws_kms_key.firewall_policy_key.key_id
}
# Data source for current AWS account ID
data "aws_caller_identity" "current" {}
This advanced configuration demonstrates a comprehensive Network Firewall Policy with both stateless and stateful rules, custom variables, threat intelligence integration, and encryption configuration.
Network Firewall Policy with TLS Inspection
This configuration shows how to integrate TLS inspection capabilities with your Network Firewall Policy:
# Create TLS inspection configuration
resource "aws_networkfirewall_tls_inspection_configuration" "main_tls_config" {
name = "main-tls-inspection"
description = "TLS inspection configuration for encrypted traffic analysis"
tls_inspection_configuration {
server_certificate_configuration {
server_certificate {
resource_arn = aws_acm_certificate.tls_inspection_cert.arn
}
scope {
protocols = [6] # TCP
source {
address_definition = "10.0.0.0/8"
}
destination {
address_definition = "0.0.0.0/0"
}
destination_port {
from_port = 443
to_port = 443
}
}
}
}
encryption_configuration {
type = "CUSTOMER_KMS"
key_id = aws_kms_key.tls_inspection_key.arn
}
tags = {
Name = "main-tls-inspection"
Environment = "production"
Purpose = "tls-inspection"
}
}
# Certificate for TLS inspection
resource "aws_acm_certificate" "tls_inspection_cert" {
domain_name = "*.example.com"
validation_method = "DNS"
lifecycle {
create_before_destroy = true
}
tags = {
Name = "tls-inspection-cert"
Environment = "production"
Purpose = "tls-inspection"
}
}
# KMS key for TLS inspection encryption
resource "aws_kms_key" "tls_inspection_key" {
description = "KMS key for TLS inspection encryption"
deletion_window_in_days = 7
enable_key_rotation = true
policy = jsonencode({
Version = "2012-10-17"
Statement = [
{
Sid = "Enable IAM User Permissions"
Effect = "Allow"
Principal = {
AWS = "arn:aws:iam::${data.aws_caller_identity.current.account_id}:root"
}
Action = "kms:*"
Resource = "*"
},
{
Sid = "Allow Network Firewall Service"
Effect = "Allow"
Principal = {
Service = "network-firewall.amazonaws.com"
}
Action = [
"kms:Decrypt",
"kms:DescribeKey",
"kms:GenerateDataKey"
]
Resource = "*"
}
]
})
tags = {
Name = "tls-inspection-key"
Environment = "production"
Purpose = "encryption"
}
}
# Network Firewall Policy with TLS inspection
resource "aws_networkfirewall_firewall_policy" "tls_inspection_policy" {
name = "tls-inspection-policy"
description = "Network Firewall Policy with TLS inspection capabilities"
firewall_policy {
stateless_default_actions = ["aws:forward_to_sfe"]
stateless_fragment_default_actions = ["aws:forward_to_sfe"]
stateful_default_actions = ["aws:drop_strict"]
# TLS inspection configuration reference
tls_inspection_configuration_arn = aws_networkfirewall_tls_inspection_configuration.main_tls_config.arn
# Enhanced stateful rules for TLS inspection
stateful_rule_group_reference {
priority = 100
resource_arn = aws_networkfirewall_rule_group.tls_inspection_rules.arn
}
stateful_engine_options {
rule_order = "STRICT_ORDER"
stream_exception_policy = "CONTINUE"
}
}
encryption_configuration {
type = "CUSTOMER_KMS"
key_id = aws_kms_key.firewall_policy_key.arn
}
tags = {
Name = "tls-inspection-policy"
Environment = "production"
Purpose = "tls-inspection"
ManagedBy = "terraform"
}
}
# Rule group for TLS inspection
resource "aws_networkfirewall_rule_group" "tls_inspection_rules" {
name = "tls-inspection-rules"
type = "STATEFUL"
capacity = 300
description = "Rules for TLS inspection and content filtering"
rule_group {
rules_source {
stateful_rule {
action = "PASS"
header {
destination = "ANY"
destination_port = "443"
direction = "FORWARD"
protocol = "TLS"
source = "ANY"
source_port = "ANY"
}
rule_option {
keyword = "sid"
settings = ["10"]
}
rule_option {
keyword = "tls.sni"
settings = ["*.trusted-domain.com"]
}
}
stateful_rule {
action = "DROP"
header {
destination = "ANY"
destination_port = "443"
direction = "FORWARD"
protocol = "TLS"
source = "ANY"
source_port = "ANY"
}
rule_option {
keyword = "sid"
settings = ["11"]
}
rule_option {
keyword = "tls.sni"
settings = ["*.malicious-domain.com"]
}
}
}
}
tags = {
Name = "tls-inspection-rules"
Environment = "production"
Purpose = "content-filtering"
}
}
This comprehensive configuration creates a Network Firewall Policy with TLS inspection capabilities, allowing the firewall to decrypt and inspect encrypted traffic for enhanced security analysis.
These Terraform configurations demonstrate how to create and manage Network Firewall Policies with varying levels of complexity, from
Best practices for Network Firewall Policy
Network Firewall Policy management requires careful planning and implementation to maintain security effectiveness while avoiding operational disruptions. Here are the key best practices to follow when working with Network Firewall Policies.
Policy Structure and Organization
Why it matters: Well-structured policies improve maintainability and reduce the risk of misconfigurations that could create security gaps or block legitimate traffic.
Implementation: Design your policies with clear naming conventions and logical grouping of rules. Use separate rule groups for different security domains (web traffic, database access, admin tools) rather than creating monolithic policies.
resource "aws_networkfirewall_firewall_policy" "web_tier_policy" {
name = "web-tier-firewall-policy-${var.environment}"
firewall_policy {
stateless_default_actions = ["aws:forward_to_sfe"]
stateless_fragment_default_actions = ["aws:forward_to_sfe"]
stateless_rule_group_reference {
priority = 100
resource_arn = aws_networkfirewall_rule_group.web_access_rules.arn
}
stateful_rule_group_reference {
priority = 200
resource_arn = aws_networkfirewall_rule_group.web_security_rules.arn
}
}
tags = {
Environment = var.environment
Purpose = "WebTierProtection"
ManagedBy = "Terraform"
}
}
Additional guidance: Keep policies focused on specific network segments or application tiers. This approach makes troubleshooting easier and reduces the blast radius when changes are needed.
Rule Group Prioritization Strategy
Why it matters: Incorrect rule ordering can lead to security bypasses or unexpected traffic blocking. Network Firewall processes rules in priority order, so proper sequencing is critical.
Implementation: Establish a clear priority numbering scheme with gaps between rule groups to allow for future insertions. Use lower numbers for more specific rules and higher numbers for general policies.
# Priority allocation strategy
# 1-99: Emergency bypass rules
# 100-199: Allow rules for critical services
# 200-299: Application-specific rules
# 300-399: General security rules
# 400-499: Logging and monitoring rules
# 500+: Default deny rules
Additional guidance: Document your priority scheme and maintain it consistently across all policies. Regular audits of rule ordering help identify potential conflicts or optimization opportunities.
Stateful vs Stateless Rule Selection
Why it matters: Choosing the wrong rule type can impact performance and security effectiveness. Stateless rules are faster but less intelligent, while stateful rules provide better security but require more processing.
Implementation: Use stateless rules for simple, high-volume traffic filtering and stateful rules for complex inspection requirements. Reserve stateful processing for traffic that requires connection tracking or deep packet inspection.
resource "aws_networkfirewall_firewall_policy" "optimized_policy" {
name = "performance-optimized-policy"
firewall_policy {
# Use stateless for simple port/protocol filtering
stateless_rule_group_reference {
priority = 50
resource_arn = aws_networkfirewall_rule_group.basic_port_filtering.arn
}
# Use stateful for complex security inspection
stateful_rule_group_reference {
priority = 100
resource_arn = aws_networkfirewall_rule_group.threat_detection.arn
}
# Override settings for stateful rules
stateful_engine_options {
rule_order = "STRICT_ORDER"
stream_exception_policy = "CONTINUE"
stateful_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.custom_rules.arn
override {
action = "DROP_TO_ALERT"
}
}
}
}
}
Additional guidance: Monitor performance metrics to ensure your rule selection doesn't create bottlenecks. Consider using capacity reservation for stateful rules to guarantee performance.
Logging and Monitoring Configuration
Why it matters: Comprehensive logging enables threat detection, compliance reporting, and troubleshooting. Without proper logging, security incidents may go undetected.
Implementation: Configure both flow logs and alert logs with appropriate destinations. Use CloudWatch for real-time monitoring and S3 for long-term retention.
resource "aws_networkfirewall_logging_configuration" "policy_logging" {
firewall_arn = aws_networkfirewall_firewall.main.arn
logging_configuration {
log_destination_config {
log_destination = {
bucketName = aws_s3_bucket.firewall_logs.bucket
prefix = "flow-logs/"
}
log_destination_type = "S3"
log_type = "FLOW"
}
log_destination_config {
log_destination = {
logGroup = aws_cloudwatch_log_group.firewall_alerts.name
}
log_destination_type = "CloudWatchLogs"
log_type = "ALERT"
}
}
}
Additional guidance: Implement log analysis automation using CloudWatch Insights or third-party SIEM tools. Set up alerts for suspicious patterns or rule violations.
Policy Testing and Validation
Why it matters: Policy changes can inadvertently block legitimate traffic or create security vulnerabilities. Thorough testing prevents production disruptions.
Implementation: Use staging environments that mirror production network topology. Test both positive cases (expected traffic flows) and negative cases (blocked malicious traffic).
# Test script for policy validation
#!/bin/bash
set -e
# Test legitimate traffic flows
echo "Testing web traffic..."
curl -f <https://app.example.com/health> || echo "FAIL: Web access blocked"
# Test blocked traffic
echo "Testing blocked ports..."
timeout 5 telnet malicious-site.com 22 2>/dev/null && echo "FAIL: SSH access not blocked" || echo "PASS: SSH properly blocked"
# Validate rule group references
aws networkfirewall describe-firewall-policy --firewall-policy-name "$POLICY_NAME" \\
--query 'FirewallPolicy.StatefulRuleGroupReferences[*].ResourceArn' \\
--output text | while read arn; do
aws networkfirewall describe-rule-group --rule-group-arn "$arn" >/dev/null || echo "FAIL: Rule group $arn not found"
done
Additional guidance: Implement automated testing as part of your CI/CD pipeline. Use gradual rollouts for policy changes in production environments.
Performance Optimization
Why it matters: Poorly optimized policies can create network bottlenecks and impact application performance. Efficient rule design maintains security without sacrificing speed.
Implementation: Place frequently matched rules at higher priorities, use rule group capacity efficiently, and monitor processing metrics.
resource "aws_networkfirewall_rule_group" "optimized_rules" {
name = "high-performance-rules"
type = "STATEFUL"
capacity = 1000
rule_group {
# Place most common rules first
rules_source {
stateful_rule {
action = "PASS"
header {
destination = "10.0.0.0/8"
destination_port = "443"
direction = "FORWARD"
protocol = "TCP"
source = "ANY"
source_port = "ANY"
}
rule_option {
keyword = "sid"
settings = ["1"]
}
}
}
# Optimize rule group settings
stateful_rule_options {
rule_order = "STRICT_ORDER"
}
}
}
Additional guidance: Regularly review CloudWatch metrics for processing latency and throughput. Consider rule group splitting if capacity limits are reached.
Security Hardening Practices
Why it matters: Default configurations may not provide adequate security for all environments. Proper hardening ensures comprehensive protection.
Implementation: Configure strict default actions, enable TLS inspection where appropriate, and implement defense-in-depth strategies.
resource "aws_networkfirewall_firewall_policy" "hardened_policy" {
name = "security-hardened-policy"
firewall_policy {
# Strict default actions
stateless_default_actions = ["aws:drop"]
stateless_fragment_default_actions = ["aws:drop"]
# TLS inspection configuration
tls_inspection_configuration_arn = aws_networkfirewall_tls_inspection_configuration.main.arn
# Policy variables for dynamic rules
policy_variables {
rule_variables {
key = "HOME_NET"
ip_set {
definition = ["10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16"]
}
}
}
}
# Encrypt policy data
encryption_configuration {
key_id = aws_kms_key.firewall_encryption.arn
type = "CUSTOMER_KMS"
}
}
Additional guidance: Implement regular security reviews and penetration testing. Keep rule groups updated with latest threat intelligence and security patches.
Integration Ecosystem
The Network Firewall Policy integrates seamlessly with numerous AWS services to provide comprehensive network security management. At the time of writing, there are 25+ AWS services that integrate with Network Firewall Policy in various capacities, including direct dependencies, logging integrations, and management interfaces.
Key integrations include direct relationships with Network Firewall Rule Groups for rule enforcement, KMS Keys for encryption of logs and sensitive data, and VPC resources for network boundary definitions. The service also works closely with CloudWatch for monitoring and logging, S3 for log storage, and IAM for access control.
The policy management extends to integration with AWS Config for compliance monitoring, CloudTrail for audit logging, and Systems Manager for configuration management. This extensive integration network ensures that Network Firewall Policies can be managed holistically within your broader AWS infrastructure strategy.
Pricing and Scale Considerations
Network Firewall Policy pricing follows AWS's standard model with no upfront costs and pay-as-you-use pricing. The cost structure includes charges for the Network Firewall endpoint ($0.395 per hour), data processing ($0.065 per GB), and storage of logs if enabled. There are no additional charges specifically for the policies themselves, as they are included in the overall Network Firewall service pricing.
Scale Characteristics
Network Firewall Policies can handle significant scale with support for up to 30,000 rules per policy across all rule groups. Each policy can reference up to 100 rule groups, and you can have multiple policies per AWS account. The service supports throughput of up to 100 Gbps per Network Firewall endpoint, with the ability to scale horizontally by deploying multiple endpoints across different Availability Zones.
Performance characteristics include sub-millisecond latency for most traffic inspection operations, with the ability to process millions of connections per second. The service automatically scales to handle traffic spikes without manual intervention, though you should monitor CloudWatch metrics to ensure optimal performance.
Enterprise Considerations
For enterprise deployments, Network Firewall Policies support advanced features including centralized management through AWS Organizations, automated policy deployment through Infrastructure as Code, and integration with third-party security tools via APIs. The service provides detailed logging and monitoring capabilities that meet enterprise compliance requirements.
AWS Network Firewall competes directly with solutions from Palo Alto Networks, Fortinet, and Check Point. However, for infrastructure running on AWS, this native integration provides significant advantages including reduced latency, simplified management, and seamless integration with other AWS security services. The managed nature of the service eliminates the need for virtual appliance management and reduces operational overhead.
Managing Network Firewall Policy using Terraform
Network Firewall Policy management through Terraform requires careful consideration of rule group dependencies and policy associations. The configuration involves multiple interconnected resources that must be created in the correct order.
Basic Network Firewall Policy Configuration
This example demonstrates a fundamental policy setup with stateless and stateful rule groups for common enterprise security requirements.
# Define a basic Network Firewall Policy
resource "aws_networkfirewall_firewall_policy" "main_policy" {
name = "production-network-policy"
firewall_policy {
stateless_default_actions = ["aws:forward_to_sfe"]
stateless_fragment_default_actions = ["aws:forward_to_sfe"]
# Reference existing rule groups
stateless_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.stateless_rules.arn
priority = 100
}
stateful_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.stateful_rules.arn
priority = 200
}
# TLS inspection configuration
tls_inspection_configuration_arn = aws_networkfirewall_tls_inspection_configuration.main.arn
# Enable policy variables for dynamic configuration
policy_variables {
rule_variables {
key = "HOME_NET"
ip_set {
definition = ["10.0.0.0/16", "172.16.0.0/12"]
}
}
rule_variables {
key = "EXTERNAL_NET"
ip_set {
definition = ["0.0.0.0/0"]
}
}
}
}
# Encryption configuration for logs
encryption_configuration {
type = "CUSTOMER_KMS"
key_id = aws_kms_key.firewall_logs.arn
}
tags = {
Name = "production-network-policy"
Environment = "production"
Team = "security"
ManagedBy = "terraform"
}
}
This configuration creates a comprehensive firewall policy with both stateless and stateful rule processing, TLS inspection capabilities, and proper encryption. The policy variables allow for dynamic IP set definitions that can be updated without modifying the core policy structure.
Key parameters include the stateless default actions which determine how traffic is handled when no specific rules match, and the rule group references that define the actual security rules. The encryption configuration ensures that any generated logs are properly secured using customer-managed KMS keys.
Advanced Policy with Multiple Rule Groups
This scenario shows a more complex policy configuration suitable for enterprise environments with multiple security layers and compliance requirements.
# Advanced Network Firewall Policy with comprehensive rule management
resource "aws_networkfirewall_firewall_policy" "enterprise_policy" {
name = "enterprise-security-policy"
firewall_policy {
stateless_default_actions = ["aws:forward_to_sfe"]
stateless_fragment_default_actions = ["aws:drop"]
# Multiple stateless rule groups for different traffic types
stateless_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.dmz_rules.arn
priority = 100
}
stateless_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.internal_rules.arn
priority = 200
}
# Stateful rule groups for application-specific rules
stateful_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.web_application_rules.arn
priority = 300
# Override default actions for this rule group
override {
action = "DROP_TO_ALERT"
}
}
stateful_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.database_rules.arn
priority = 400
}
# Configure stateful engine options
stateful_engine_options {
rule_order = "STRICT_ORDER"
stream_exception_policy = "CONTINUE"
}
# Extensive policy variables for different network segments
policy_variables {
rule_variables {
key = "WEB_SERVERS"
ip_set {
definition = ["10.0.1.0/24", "10.0.2.0/24"]
}
}
rule_variables {
key = "DB_SERVERS"
ip_set {
definition = ["10.0.10.0/24"]
}
}
rule_variables {
key = "MANAGEMENT_HOSTS"
ip_set {
definition = ["10.0.100.0/24"]
}
}
# Port variables for common services
rule_variables {
key = "HTTP_PORTS"
port_set {
definition = ["80", "443", "8080", "8443"]
}
}
}
}
# Enhanced encryption and logging configuration
encryption_configuration {
type = "CUSTOMER_KMS"
key_id = aws_kms_key.firewall_logs.arn
}
tags = {
Name = "enterprise-security-policy"
Environment = "production"
Compliance = "SOC2"
SecurityLevel = "high"
Team = "security"
ManagedBy = "terraform"
}
}
# Associated KMS key for encryption
resource "aws_kms_key" "firewall_logs" {
description = "KMS key for Network Firewall logs encryption"
policy = jsonencode({
Version = "2012-10-17"
Statement = [
{
Sid = "Enable IAM User Permissions"
Effect = "Allow"
Principal = {
AWS = "arn:aws:iam::${data.aws_caller_identity.current.account_id}:root"
}
Action = "kms:*"
Resource = "*"
}
]
})
tags = {
Name = "firewall-logs-encryption"
Team = "security"
}
}
This advanced configuration demonstrates enterprise-grade policy management with multiple rule groups, comprehensive variable definitions, and enhanced security features. The stateful engine options provide fine-grained control over rule processing, while the policy variables enable dynamic configuration management across different network segments.
Best Practices for Network Firewall Policy
Network Firewall Policy implementation requires careful planning and adherence to security best practices to ensure effective protection while maintaining network performance.
Implement Layered Security Architecture
Why it matters: A layered security approach provides multiple checkpoints for traffic inspection, reducing the risk of security breaches and improving overall network protection.
Implementation: Structure your policies with both stateless and stateful rules, using stateless rules for high-performance basic filtering and stateful rules for application-layer inspection.
# Example rule group priority structure
# Priority 100-199: Stateless rules (basic filtering)
# Priority 200-299: Stateful rules (application inspection)
# Priority 300-399: Custom application rules
# Priority 400-499: Compliance-specific rules
Design your rule groups with clear separation of concerns, where each group handles specific types of traffic or security requirements. This approach makes policies easier to manage and troubleshoot while providing comprehensive security coverage.
Use Policy Variables for Dynamic Configuration
Why it matters: Policy variables allow you to update IP addresses, port ranges, and other network parameters without modifying the core policy structure, enabling easier maintenance and reducing deployment errors.
Implementation: Define variables for all network segments, common ports, and frequently changing IP addresses to enable flexible policy management.
# Define comprehensive policy variables
policy_variables {
rule_variables {
key = "PRODUCTION_SUBNETS"
ip_set {
definition = ["10.0.1.0/24", "10.0.2.0/24", "10.0.3.0/24"]
}
}
rule_variables {
key = "ALLOWED_PORTS"
port_set {
definition = ["80", "443", "22", "3389"]
}
}
}
Regularly review and update these variables to reflect changes in your network architecture. Use descriptive names that clearly indicate the purpose of each variable, and document their intended use in your infrastructure documentation.
Enable Comprehensive Logging and Monitoring
Why it matters: Detailed logging provides visibility into network traffic patterns, security events, and policy effectiveness, enabling proactive security management and compliance reporting.
Implementation: Configure logging for all firewall activities and integrate with CloudWatch for monitoring and alerting.
# Enable CloudWatch logging for Network Firewall
aws logs create-log-group --log-group-name /aws/networkfirewall/flowlogs
aws logs create-log-group --log-group-name /aws/networkfirewall/alert
# Configure log retention policies
aws logs put-retention-policy \\
--log-group-name /aws/networkfirewall/flowlogs \\
--retention-in-days 90
Set up CloudWatch alarms for suspicious traffic patterns, rule violations, and performance metrics. Create dashboards that provide real-time visibility into firewall performance and security events, enabling rapid response to potential threats.
Implement Least Privilege Access Principles
Why it matters: Restricting access to only necessary resources and protocols reduces the attack surface and limits potential damage from security breaches.
Implementation: Design rules that explicitly allow only required traffic and deny everything else by default.
# Example of least privilege rule configuration
stateful_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.web_tier_rules.arn
priority = 200
# Override to drop rather than alert for unauthorized access
override {
action = "DROP_TO_ALERT"
}
}
Regularly audit your rules to ensure they still reflect current business requirements. Remove or disable rules that are no longer needed, and review access patterns to identify opportunities for further restriction.
Test Policy Changes in Non-Production Environments
Why it matters: Network firewall policy changes can have significant impact on application connectivity and performance, making thorough testing essential before production deployment.
Implementation: Maintain separate firewall policies for different environments and use a structured testing approach.
# Test policy deployment process
terraform plan -target=aws_networkfirewall_firewall_policy.staging_policy
terraform apply -target=aws_networkfirewall_firewall_policy.staging_policy
# Validate connectivity after policy deployment
aws networkfirewall describe-firewall-policy \\
--firewall-policy-arn arn:aws:network-firewall:region:account:firewall-policy/staging-policy
Create automated tests that verify expected traffic flows after policy changes. Use network testing tools to validate that legitimate traffic is allowed while unauthorized access is blocked. Document test procedures and maintain test cases that can be executed consistently across environments.
Optimize Rule Performance and Ordering
Why it matters: Proper rule ordering and optimization reduces processing overhead and improves network performance while maintaining security effectiveness.
Implementation: Order rules from most specific to least specific, and place frequently matched rules at higher priorities.
# Optimize rule ordering for performance
stateless_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.high_volume_rules.arn
priority = 100 # Process high-volume traffic first
}
stateless_rule_group_reference {
resource_arn = aws_networkfirewall_rule_group.exception_rules.arn
priority = 200 # Handle exceptions before general rules
}
Regularly review rule performance metrics in CloudWatch to identify bottlenecks or inefficient rules. Consider consolidating similar rules or using more efficient matching criteria to improve overall performance.
Terraform and Overmind for Network Firewall Policy
Overmind Integration
Network Firewall Policy is used in many places in your AWS environment. Changes to network firewall policies can have wide-ranging impacts across your infrastructure, affecting application connectivity, security posture, and network performance.
When you run overmind terraform plan with Network Firewall Policy modifications, Overmind automatically identifies all resources that depend on your firewall configurations, including:
- VPC Resources - Subnets, route tables, and network ACLs that route traffic through the firewall
- EC2 Instances - Virtual machines whose network access is controlled by the firewall policies
- Load Balancers - Application and network load balancers that depend on firewall rules for traffic routing
- RDS Instances - Database instances whose network access is managed through firewall policies
This dependency mapping extends beyond direct relationships to include indirect dependencies that might not be immediately obvious, such as applications running on EC2 instances that depend on specific network access patterns, or microservices that communicate through firewall-controlled network paths.
Risk Assessment
Overmind's risk analysis for Network Firewall Policy changes focuses on several critical areas:
High-Risk Scenarios:
- Rule Deletion or Modification: Removing or changing existing rules that current applications depend on for network access
- Default Action Changes: Modifying default actions from allow to deny, which could block legitimate traffic
- TLS Inspection Changes: Altering TLS inspection configurations that could break encrypted application communications
Medium-Risk Scenarios:
- Rule Priority Adjustments: Changing rule priorities that could affect the order of rule processing and traffic handling
- Policy Variable Updates: Modifying IP sets or port sets that are referenced across multiple rules
Low-Risk Scenarios:
- Rule Additions: Adding new rules that don't conflict with existing access patterns
- Tag Updates: Modifying resource tags that don't affect policy functionality
Use Cases
Multi-Tier Application Security
Network Firewall Policy excels in protecting multi-tier applications by providing granular control over traffic between application layers. For example, an e-commerce platform can use firewall policies to enforce that web servers only communicate with application servers on specific ports, while database servers only accept connections from application servers.
The policy can