Configuring Network Policies to Restrict Pod Access

Relationships Between Network Policies and Cluster Types

Using Ingress Rules Through YAML

• Scenario 1: Use a network policy to limit access to a pod to only pods with specific labels.

  Figure 1 podSelector

  
  

  The pod labeled with role=db only permits access to its port 6379 from pods labeled with role=frontend. To do so, perform the following operations:

  1. Create the access-demo1.yaml file.

     vim access-demo1.yaml
     
     

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-demo1
       namespace: default
     spec:
       podSelector:                  # The rule takes effect for pods with the role=db label.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - podSelector:              # Only allow the access of the pods labeled with role=frontend.
             matchLabels:
               role: frontend
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379
     
     

  2. Run the following command to create the network policy based on the access-demo1.yaml file:

     kubectl apply -f access-demo1.yaml
     
     

     Expected output:

     networkpolicy.networking.k8s.io/access-demo1 created
     
     

• Scenario 2: Use a network policy to limit access to a pod to only pods in a specific namespace.

  Figure 2 namespaceSelector

  
  

  The pod labeled with role=db only permits access to its port 6379 from pods in the namespace labeled with project=myproject. To do so, perform the following operations:

  1. Create the access-demo2.yaml file.

     vim access-demo2.yaml
     
     

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-demo2
     spec:
       podSelector:                  # The rule takes effect for pods with the role=db label.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - namespaceSelector:        # Only allow the access of the pods in the namespace labeled with project=myproject.
             matchLabels:
               project: myproject
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379
     
     

  2. Run the following command to create the network policy based on the access-demo2.yaml file:

     kubectl apply -f access-demo2.yaml
     
     

     Expected output:

     networkpolicy.networking.k8s.io/access-demo2 created
     
     

Using Egress Rules Through YAML

• Scenario 1: Use a network policy to limit a pod's access to specific addresses.

  Figure 3 IPBlock

  
  

  The pod labeled with role=db only permits access to the 172.16.0.0/16 CIDR block, excluding 172.16.0.40/32 within it. To do so, perform the following operations:

  1. Create the access-demo3.yaml file.

     vim access-demo3.yaml
     
     

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-demo3
       namespace: default
     spec:
       policyTypes:                  # Must be specified for an egress rule.
         - Egress
       podSelector:                  # The rule takes effect for pods with the role=db label.
         matchLabels:
           role: db
       egress:                       # Egress rule
       - to:
         - ipBlock:
             cidr:172.16.0.0/16    # Allow access to this CIDR block in the outbound direction.
             except:
             - 172.16.0.40/32        # Block access to this address in the CIDR block.
     
     

  2. Run the following command to create the network policy based on the access-demo3.yaml file:

     kubectl apply -f access-demo3.yaml
     
     

     Expected output:

     networkpolicy.networking.k8s.io/access-demo3 created
     
     

• Scenario 2: Use a network policy to limit access to a pod to only pods with specific labels and this pod can only access specific pods.

  Figure 4 Using both ingress and egress

  
  

  The pod labeled with role=db only permits access to its port 6379 from pods labeled with role=frontend, and this pod can only access the pods labeled with role=web. You can use the same rule to configure both ingress and egress in a network policy. To do so, perform the following operations:

  1. Create the access-demo4.yaml file.

     vim access-demo4.yaml
     
     

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-demo4
       namespace: default
     spec:
       policyTypes:
       - Ingress
       - Egress
       podSelector:                  # The rule takes effect for pods with the role=db label.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - podSelector:              # Only allow the access of the pods labeled with role=frontend.
             matchLabels:
               role: frontend
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379
       egress:                       # Egress rule
       - to:
         - podSelector:              # Only pods with the role=web label can be accessed.
             matchLabels:
               role: web
     
     

  2. Run the following command to create the network policy based on the access-demo4.yaml file:

     kubectl apply -f access-demo4.yaml
     
     

     Expected output:

     networkpolicy.networking.k8s.io/access-demo4 created
     
     

Creating a Network Policy on the Console

1. Log in to the CCE console and click the cluster name to access the cluster console.
2. Choose Policies in the navigation pane, click the Network Policies tab, and click Create Network Policy in the upper right corner.
   • Policy Name: Specify a network policy name.
   • Namespace: Select a namespace in which the network policy is applied.
   • Selector: Enter a label, select the pod to be associated, and click Add. You can also click Reference Workload Label to use the label of an existing workload.
   • Inbound Rule: Click to add an inbound rule. For details about parameter settings, see Table 1.

     Table 1 Adding an inbound rule

     Parameter	Description
     Protocol & Port	Select the protocol type and port. Currently, TCP and UDP are supported.
     Source CIDR Block	For clusters of v1.27.16-r10, v1.28.15-r0, v1.29.10-r0, v1.30.6-r0, or later versions with DataPlane V2 enabled, you can configure the source CIDR block. The specified source CIDR block allows traffic from a destination CIDR block (multiple exception CIDR blocks can be specified). Separate the destination and exception CIDR blocks using a vertical bar (|). If there are multiple exception CIDR blocks, separate them using commas (,). For example, 172.17.0.0/16|172.17.1.0/24,172.17.2.0/24 indicates that 172.17.0.0/16 is accessible, but not for 172.17.1.0/24 and 172.17.2.0/24.
     Source Namespace	Select a namespace whose objects can be accessed. If this parameter is not specified, the object belongs to the same namespace as the current policy.
     Source Pod Label	Allow accessing the pods with this label. If this parameter is not specified, all pods in the namespace can be accessed.

   • Outbound Rule: Click to add an outbound rule. For details about parameter settings, see Table 2.

     Table 2 Adding an outbound rule

     Parameter	Description
     Protocol & Port	Select the protocol type and port. Currently, TCP and UDP are supported. If this parameter is not specified, the protocol type is not limited.
     Destination CIDR Block	Allows requests to be routed to a specified CIDR block (and not to the exception CIDR blocks). Separate the destination and exception CIDR blocks using a vertical bar (|). If there are multiple exception CIDR blocks, separate them using commas (,). For example, 172.17.0.0/16|172.17.1.0/24,172.17.2.0/24 indicates that 172.17.0.0/16 is accessible, but not for 172.17.1.0/24 and 172.17.2.0/24.
     Destination Namespace	Select a namespace whose objects can be accessed. If this parameter is not specified, the object belongs to the same namespace as the current policy.
     Destination Pod Label	Allow accessing the pods with this label. If this parameter is not specified, all pods in the namespace can be accessed.

3. Click OK.