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Networking (VPC & SDN)Door LYNIO Support

Securing Infrastructure with Security Lists

Security Lists act as virtual firewalls for your Compute Instances, controlling both inbound (ingress) and outbound (egress) traffic at the network level.

How Security Lists Work

Unlike traditional OS-level firewalls (like iptables or ufw), Security Lists operate at the hypervisor level. This means traffic is filtered before it even reaches your instance.

A Security List contains a set of rules. Each rule specifies:

  • Direction: Ingress (incoming) or Egress (outgoing).
  • Protocol: TCP, UDP, ICMP, or ALL.
  • Port Range: A specific port (e.g., 80) or a range (e.g., 8000-9000).
  • Source/Destination CIDR: The IP range allowed to connect (e.g., 0.0.0.0/0 for anyone).

Default Behavior

By default, LYNIO instances are launched with a restrictive profile:

  • Ingress: All incoming traffic is denied.
  • Egress: All outgoing traffic is allowed.

Adding a New Rule

To allow web traffic (HTTP and HTTPS) to your instance:

  1. Navigate to Networking > Security Lists.
  2. Click on the default Security List or create a new one.
  3. Go to the Ingress Rules tab.
  4. Click Add Rule.
  5. Configure the rule for HTTP:
    • Protocol: TCP
    • Port: 80
    • Source CIDR: 0.0.0.0/0 (Allow from anywhere)
  6. Add another rule for HTTPS:
    • Protocol: TCP
    • Port: 443
    • Source CIDR: 0.0.0.0/0
  7. Click Save Changes.

Applying Security Lists

Security Lists can be applied directly to a VPC Subnet (affecting all instances in that subnet) or directly to individual Compute Instances.

To verify your rules are working, you can use curl to test HTTP access from your local machine:

curl -I http://<INSTANCE_IP>

If you receive an HTTP 200 OK response, your Security List is correctly configured.