Should I use network tags or service accounts for firewall rule targets?

Service accounts are more secure because they are managed through IAM and cannot be modified by instance administrators. Network tags can be changed by anyone with compute.instances.setTags permission, which means a compromised instance could potentially add tags to gain access to additional firewall rules. Google recommends service account-based targeting for production workloads and uses network tags primarily for development environments or simpler configurations.

How does GCP firewall rule priority work compared to AWS Security Groups?

GCP firewall rules use explicit numeric priority (0-65535) where lower numbers take precedence. The default rules have priority 65534-65535. When multiple rules match, only the highest-priority (lowest number) rule applies. AWS Security Groups have no priority concept — all rules are evaluated together, and traffic is allowed if any rule matches. GCP's priority system allows you to create exception patterns (a specific allow at priority 900 overriding a broad deny at priority 1000) that are not possible with AWS Security Groups.

What is the implied deny-all rule in GCP firewall?

Every GCP VPC network has two implied firewall rules that cannot be deleted: an implied allow-all egress rule (priority 65535) and an implied deny-all ingress rule (priority 65535). This means all outbound traffic is allowed by default, and all inbound traffic is denied unless you create explicit allow rules. You can override these implied rules by creating rules at higher priority (lower numbers). The default network also includes pre-populated rules allowing internal traffic, SSH, RDP, and ICMP.

GCP Firewall Rule Builder

IAM & SecurityGCP

Build GCP VPC firewall rules with priority, direction, and target configuration.

Firewall Rule Configuration

Preset

Rule Name

Lowercase letters, numbers, and hyphens only (1-63 chars)

Network

Direction

Action

Priority

0 (highest) to 65535 (lowest). Default is 1000.

Protocols and Ports

Source Ranges (CIDR, one per line)

Target Tags (one per line)

Description (optional)

Rule disabled

Output

Output will appear here...

About This Tool

GCP VPC firewall rules control traffic to and from instances based on direction, priority, protocol/port combinations, and target/source specifiers like network tags, service accounts, or IP ranges. Unlike AWS security groups, GCP firewall rules are defined at the VPC network level and use a priority system (0-65535, lower wins) that determines which rule takes effect when multiple rules match the same traffic. This builder provides a structured form for specifying direction, priority, targets, sources/destinations, and protocol/port pairs, generating valid gcloud commands or Terraform configuration for deployment.

When to Use This Tool

•Creating ingress rules that restrict SSH access to specific IP ranges using network tags to target only bastion host instances
•Building egress rules that block outbound traffic to the internet for backend instances while allowing access to internal APIs
•Configuring priority-based rule sets where a specific allow rule (priority 1000) overrides a broader deny rule (priority 2000)
•Generating firewall rules that use service account-based targeting instead of network tags for more secure identity-based access control

Frequently Asked Questions

Should I use network tags or service accounts for firewall rule targets?: Service accounts are more secure because they are managed through IAM and cannot be modified by instance administrators. Network tags can be changed by anyone with compute.instances.setTags permission, which means a compromised instance could potentially add tags to gain access to additional firewall rules. Google recommends service account-based targeting for production workloads and uses network tags primarily for development environments or simpler configurations.
How does GCP firewall rule priority work compared to AWS Security Groups?: GCP firewall rules use explicit numeric priority (0-65535) where lower numbers take precedence. The default rules have priority 65534-65535. When multiple rules match, only the highest-priority (lowest number) rule applies. AWS Security Groups have no priority concept — all rules are evaluated together, and traffic is allowed if any rule matches. GCP's priority system allows you to create exception patterns (a specific allow at priority 900 overriding a broad deny at priority 1000) that are not possible with AWS Security Groups.
What is the implied deny-all rule in GCP firewall?: Every GCP VPC network has two implied firewall rules that cannot be deleted: an implied allow-all egress rule (priority 65535) and an implied deny-all ingress rule (priority 65535). This means all outbound traffic is allowed by default, and all inbound traffic is denied unless you create explicit allow rules. You can override these implied rules by creating rules at higher priority (lower numbers). The default network also includes pre-populated rules allowing internal traffic, SSH, RDP, and ICMP.

Disclaimer: This tool runs entirely in your browser. No data is sent to our servers. Always verify outputs before using them in production. AWS, Azure, and GCP are trademarks of their respective owners.