Firewall ingress and egress rules in Google Cloud Platform (GCP) are essential components of Virtual Private Cloud (VPC) network security that control traffic flow to and from your cloud resources.
**Ingress Rules** govern incoming traffic to your VPC network resources. These rules determine which…Firewall ingress and egress rules in Google Cloud Platform (GCP) are essential components of Virtual Private Cloud (VPC) network security that control traffic flow to and from your cloud resources.
**Ingress Rules** govern incoming traffic to your VPC network resources. These rules determine which external connections can reach your instances, load balancers, and other services. When configuring ingress rules, you specify source IP ranges, protocols, ports, and target resources. For example, you might create an ingress rule allowing HTTP traffic (port 80) from any IP address (0.0.0.0/0) to reach web servers tagged with 'web-server'.
**Egress Rules** control outbound traffic from your VPC resources to external destinations. These rules define what connections your instances can initiate to other networks or the internet. By default, GCP allows all egress traffic, but you can restrict this for security compliance. For instance, you might block all outbound traffic except to specific approved IP ranges.
**Key Components of Firewall Rules:**
- **Priority**: Lower numbers indicate higher priority (0-65535)
- **Direction**: Ingress or egress
- **Action**: Allow or deny
- **Targets**: All instances, specific tags, or service accounts
- **Source/Destination**: IP ranges, tags, or service accounts
- **Protocols and Ports**: TCP, UDP, ICMP with specific port numbers
**Best Practices:**
1. Follow the principle of least privilege - only allow necessary traffic
2. Use network tags or service accounts for granular targeting
3. Document all rules for audit purposes
4. Regularly review and remove unused rules
5. Set appropriate priorities to ensure correct rule evaluation order
**Default Behavior:**
GCP includes implied rules: a default deny-all ingress rule and a default allow-all egress rule. Custom rules override these defaults based on priority settings, enabling precise control over network traffic patterns.
Firewall Ingress and Egress Rules in Google Cloud Platform
Why Firewall Rules Are Important
Firewall rules are fundamental to securing your cloud infrastructure. They act as the first line of defense, controlling what traffic can enter (ingress) and leave (egress) your Virtual Private Cloud (VPC) networks. Properly configured firewall rules protect your resources from unauthorized access, data breaches, and malicious attacks while allowing legitimate traffic to flow.
What Are Firewall Ingress and Egress Rules?
Ingress Rules control incoming traffic to your instances. They determine which external sources can communicate with your VMs and on which ports and protocols.
Egress Rules control outgoing traffic from your instances. They specify which destinations your VMs can reach and through which ports and protocols.
Key components of firewall rules include: - Direction: Ingress or Egress - Priority: A number from 0-65535 (lower numbers = higher priority) - Action: Allow or Deny - Target: Which instances the rule applies to (all instances, specific tags, or service accounts) - Source/Destination: IP ranges, tags, or service accounts - Protocol and Ports: TCP, UDP, ICMP, or specific port numbers
How Firewall Rules Work
GCP firewall rules are stateful, meaning if you allow incoming traffic, the response is automatically allowed regardless of egress rules.
Rules are evaluated by priority (lowest number first). When a matching rule is found, that action is taken and no further rules are evaluated.
Default Rules: - Implied deny ingress: All incoming traffic is denied by default (priority 65535) - Implied allow egress: All outgoing traffic is allowed by default (priority 65535) - These implied rules cannot be deleted but can be overridden with higher priority rules
Network Tags vs Service Accounts: - Network tags are simpler but less secure (any user with instance edit permissions can modify tags) - Service accounts provide stronger security as they require IAM permissions to modify
Exam Tips: Answering Questions on Firewall Ingress and Egress Rules
1. Remember the defaults: By default, all ingress is denied and all egress is allowed. Questions often test this knowledge.
2. Priority matters: Lower numbers mean higher priority. A rule with priority 100 is evaluated before priority 1000.
3. Stateful behavior: Understand that return traffic for allowed connections is permitted. If a question involves response traffic, remember it flows through because of statefulness.
4. Scope of rules: Firewall rules are defined at the VPC network level but apply to individual instances based on targets.
5. Tags vs Service Accounts: For questions about security best practices, service accounts are preferred over network tags for applying firewall rules.
6. 0.0.0.0/0: This CIDR range means all IP addresses. Questions may use this to represent internet-facing rules.
7. Least privilege principle: When asked about best practices, choose answers that limit access to only what is necessary.
8. Common scenarios: Know how to allow SSH (TCP port 22), HTTP (TCP port 80), HTTPS (TCP port 443), and RDP (TCP port 3389).
9. VPC Flow Logs: These help monitor firewall rule effectiveness and are often mentioned in troubleshooting scenarios.
10. Hierarchical Firewall Policies: Organization and folder-level policies take precedence over VPC firewall rules. Consider this in multi-project scenarios.