module-4-security-guardrails.md

Module 4 - Security Guardrails for Network-based Threats

Calico provides methods to enable fine-grained access controls between your microservices and external databases, cloud services, APIs, and other applications protected by a firewall. You can enforce controls from within the cluster using DNS egress policies from a firewall outside the cluster using the egress gateway. Controls are applied on a fine-grained, per-pod basis.

In this module, we will learn how to use Calico to create network policies to control access to and from a pod. We will install the Example Voting Application. Once the application is deployed, we will create and test network security policies with different ingress and egress rules to demonstrate how the workload access control is done.

1. Installing the example application stacks:

   From the cloned directory, execute:

   kubectl apply -f pre
   

Included in the pre folder, there is an application that will be used in the exercises during the workshop. The diagram below shows how the elements of this application communicate between themselves.

There are also other objects that will be created. We will learn about them later in the workshop.

Note: Wait until all the pods are up and running to move to the next step.

Service Graph and Flow Visualizer

Connect to Calico Cloud GUI. From the menu, select Service Graph > Default. Explore the options.

Connect to Calico Cloud GUI. From the menu select Service Graph > Flow Visualizations. Explore the options.

Security Policies

Calico Security Policies provide a richer set of policy capabilities than the native Kubernetes network policies, including:

• Policies that can be applied to any endpoint: pods/containers, VMs, and/or to host interfaces
• Policies that can define rules that apply to ingress, egress, or both
• Policy rules support:
  • Actions: allow, deny, log, pass
  • Source and destination match criteria:
    • Ports: numbered, ports in a range, and Kubernetes named ports
    • Protocols: TCP, UDP, ICMP, SCTP, UDPlite, ICMPv6, protocol numbers (1-255)
    • HTTP attributes (if using Istio service mesh)
    • ICMP attributes
    • IP version (IPv4, IPv6)
    • IP or CIDR
    • Endpoint selectors (using label expression to select pods, VMs, host interfaces, and/or network sets)
    • Namespace selectors
    • Service account selectors

The Zero Trust approach

A global default deny policy ensures that unwanted traffic (ingress and egress) is denied by default. Pods without policy (or incorrect policy) are not allowed traffic until the appropriate network policy is defined. Although the staging policy tool will help you find the incorrect or the missing policy, a global deny policy helps mitigate other lateral malicious attacks.

By default, all traffic is allowed between the pods in a cluster. Let's start by testing connectivity between application components and across application stacks. All of these tests should succeed as there are no policies in place.

We recommend creating a global default deny policy after you complete writing the policy for the traffic you want to allow. Use the stage policy feature to get your allowed traffic working as expected, then lock down the cluster to block unwanted traffic.

1. Create a staged global default-deny policy. It will show all the traffic that would be blocked if it were enforced.

   • Go to the Policies Board
   • On the bottom of the tier box default click on Add Policy
     • In the Create Policy page enter the policy name: default-deny
     • On the Applies To session, click Add Namespace Seletor First, lets apply only to the vote namespace
       • Select Key... kubernetes.io/metadata.name
       • =
       • Select Value... vote
     • On the field Type select both checkboxes: Ingress and Egress.
     • You are done. Click Stage on the top-right of your page.

   The staged policy does not affect the traffic directly but allows you to view the policy impact if it were to be enforced. You can see the denied traffic in the staged policy.

2. Based on the application design, the db lists on port 5432 and receive connections from the worker and the result microservices. Let's use the Calico Cloud UI to create a policy to microsegment this traffic.

   • Go to the Policies Board
   • On the bottom of the tier box platform click on Add Policy
     • In the Create Policy page enter the policy name: db
     • Change the Scope from Global to Namespace and select the namespace vote
     • On the Applies To session, click Add Label Seletor
       • Select Key... app
       • =
       • Select Value... db
       • Click on SAVE LABEL SELECTOR
     • On the field Type select the checkbox for Ingress.
     • Click on Add Ingress Rule
       • On the Create New Policy Rule window,
         • Click on the dropdown with Any Protocol
         • Change the radio button to Protocol is and select TCP
         • In the field To: click on Add Port
         • Port is 5432 - Save
         • In the field From:, click Add Label Seletor
           • Select Key... app
           • =
           • Select Value... worker
           • Click on SAVE LABEL SELECTOR
           • On OR, click Add Label Seletor
           • Select Key... app
           • =
           • Select Value... result
           • Click on SAVE LABEL SELECTOR
         • Click on the button Save Rule
     • You are done. Click Enforce on the top-right of your page.

3. Now that you learned how to create policies using Calico Cloud UI, go ahead and create microsegmentation policies for all other workloads in the application.

4. If you create all the policies correctly, at some point, you will start seeing zero traffic being denied by your default-deny staged policy. At that point, you can go ahead and enforce the default-deny policy. Voilà! The vote namespace is now secure.

Bonus - About Tiers

Tiers are a hierarchical construct used to group policies and enforce higher precedence policies that other teams cannot circumvent, providing the basis for Identity-aware micro-segmentation.

All Calico and Kubernetes security policies reside in tiers. You can start “thinking in tiers” by grouping your teams and the types of policies within each group, such as security, platform, etc.

Policies are processed in sequential order from top to bottom.

Two mechanisms drive how traffic is processed across tiered policies:

• Labels and selectors
• Policy action rules

For more information about tiers, please refer to the Calico Cloud documentation Understanding policy tiers

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➡️ Module 5 - Configuring IDS protection and Workload-Centric WAF

⬅️ Module 3 - Calico Cloud Admission Controller
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