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Container Service for Kubernetes:Use network policies in ACK clusters

Last Updated:Aug 07, 2024

You can use network policies provided by Container Service for Kubernetes (ACK) to implement policy-based access control. If you use the Terway network plug-in and you want to control network traffic based on IP addresses or ports, you can configure network policies to control access to specific applications. This topic describes how to use network policies in an ACK cluster and the common use scenarios of the network policies.

Prerequisites

Usage notes

  • To use network policies in the ACK console, go to the Quota Center console page to submit an application.

  • To use network policies through a CLI, you do not need to apply to be added to a whitelist.

  • You can use label selectors in network policies to select namespaces and pods. If you create a large number of network policies in a cluster, the process of matching requests against rules in network policies will be time-consuming. In addition, cluster management and troubleshooting become complicated if the cluster has a large number of network policies. We recommend that you create less than 40 network policies in a cluster.

Supported items

When you create a cluster, the implementation of the network policies depends on the version of the Terway plug-in.

Version 1.9.0 and later

Component

Network policy implementation

terway-eniip

eBPF

Important
  • If you want to use network policies to match pods in the cluster, you can use podSelector or namespaceSelector. The ipBlock selector can be used to match addresses outside the cluster.

  • If the initial version of Terway is earlier than 1.9.0 when you create a cluster, the implementation of network policies remains unchanged after Terway is updated to 1.9.0 or later.

  • The kernel version required by Extended Berkeley Packet Filter (eBPF)-based network policies must be 4.19 or later. If the kernel versions of your nodes are earlier than 4.19, the network policies do not take effect.

  • The preceding description applies only to regular Elastic Container Instances that run Terway. For more information about how to enable network policies on virtual nodes, see Use network policies.

Versions earlier than 1.9.0

Component

Network policy implementation

The terway-eniip component is installed, and DataPath V2 or IPVLAN is disabled.

iptables

The terway-eniip component is installed, and DataPath V2 or IPVLAN is enabled.

eBPF

Important
  • If you want to use network policies to match pods in the cluster, you can use podSelector or namespaceSelector. For eBPF-based network policies, the ipBlock selector can be used to match addresses outside the cluster.

  • If the initial version of Terway is earlier than 1.9.0 when you create a cluster, the implementation of network policies remains unchanged after Terway is updated to 1.9.0 or later.

  • The kernel version required for the eBPF-based network policies must be 4.19 or later. If the kernel versions of your nodes are earlier than 4.19, the network policy feature reverts to the iptables mode. Network policies may not take effect as expected.

  • The preceding description applies only to regular Elastic Container Instances that run Terway. For more information about how to enable network policies on virtual nodes, see Use network policies.

Enable network policies

You can enable network policies when you create a cluster or after a cluster is created.

Created clusters

When you create a cluster, select Support for NetworkPolicy to enable the network policy feature. For more information, see Create an ACK Pro cluster.

Existing clusters

  1. Log on to the ACK console. In the left-side navigation pane, click Clusters.

  2. On the Clusters page, find the cluster that you want to manage and click its name. In the left-side navigation pane, choose Operations > Add-ons.

  3. Click the Networking tab, find the terway-eniip component, and click Configuration. In the dialog box that appears, select Enable NetworkPolicy and then click OK.

    image

Examples on using network policies

Prepare an application

Perform the following steps to create an NGINX application that allows access from other pods:

Use the ACK console

  1. Log on to the ACK console. In the left-side navigation pane, click Clusters.

  2. On the Clusters page, click the name of the cluster that you want to manage and choose Workloads > Deployments in the left-side navigation pane.

  3. On the Deployments tab, click Create from Image. On the Create page, create an application named nginx and expose the application by using a Service. After you complete the application configuration, click Create.

    You can configure the following parameters based on the description in the following table and use default settings for other parameters. For more information, see Create a Deployment from an image.

    Parameter

    Description

    Example

    Basic Information

    Name

    Specify a custom application name.

    nginx

    Replicas

    Specify the value based on your business requirements.

    1

    Container

    Image Name

    Specify the name of the container image.

    nginx:latest

    Advanced

    Services

    Click Create to the right of Services. In the Create Service dialog box, set the parameters.

    Name: nginx

    Type:

    • Server Load Balancer

    • Public Access

    • Create SLB Instance

    Port Mapping:

    • Name: nginx

    • Service Port: 80

    • Container Port: 80

    • Protocol: TCP

  4. Return to the Deployments page and click Create from Image. On the Create page, create a client application named busybox to test the accessibility of the nginx Service created in the preceding step.

    You can configure the following parameters for the busybox client application based on the description in the following table and use default settings for other parameters. For more information, see Create a Deployment from an image.

    Parameter

    Description

    Example

    Basic Information

    Name

    Specify a custom application name.

    busybox

    Replicas

    Specify a value based on your business requirements.

    1

    Container Start Parameter

    Image Name

    Specify the name of the container image.

    busybox:latest

    Container Start Parameter

    None.

    Select stdin and tty.

  5. Check whether the busybox client application can access the nginx Service.

    1. On the Deployments page, find the busybox application and click its name.

    2. On the Pods page, select a pod named busybox-{hash value} and click Terminal in the Actions column.

      image.png

    3. In the terminal, run the wget nginx command to access the nginx Service.

      connection

      The preceding output indicates that busybox can access the nginx Service.

Use the CLI

  1. Run the following command to create an application named nginx. Then, create a Service named nginx to expose the application.

    Create an application named nginx:

    kubectl run nginx --image=nginx

    Expected output:

    pod/nginx created

    Query whether the pod of the application is started:

    kubectl get pod

    Expected output:

    NAME                     READY   STATUS    RESTARTS   AGE
    nginx                    1/1     Running   0          45s

    Create a Service named nginx:

    kubectl expose pod nginx --port=80

    Expected output:

    service/nginx exposed

    View the Service:

    kubectl get service

    Expected output:

    NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
    kubernetes   ClusterIP   172.XX.XX.1     <none>        443/TCP   30m
    nginx        ClusterIP   172.XX.XX.48    <none>        80/TCP    12s
  2. Run the following command to create a pod named busybox and use the pod to access the nginx Service:

    kubectl run busybox --rm -ti --image=busybox /bin/sh

    Expected output:

    If you don't see a command prompt, try pressing enter.
    / #
    / #

    Obtain the nginx Service:

    If you don't see a command prompt, try pressing enter.
    / #
    / # wget nginx  # Enter wget nginx.

    Expected output:

    Connecting to nginx (172.XX.XX.48:80)
    saving to 'index.html'
    index.html           100% |****************************************************************************************************************************************************|   612  0:00:00 ETA
    'index.html' saved

Scenario 1: Allow only applications with specific labels to access a Service

Use the ACK console

  1. Log on to the ACK console. In the left-side navigation pane, click Clusters.

  2. On the Clusters page, find the cluster that you want to manage and click its name. In the left-side pane, choose Network > Network Policies.

  3. In the upper part of the Network Policies page, select the namespace where you want to create the network policy. In this example, the default namespace is selected. In the upper-right corner of the page, click Create. In the Create panel, configure the network policy.

    Parameter

    Description

    Example

    Parameter

    Specify a custom network policy name.

    access-nginx

    Pod Selectors

    Click + Specify workload type and labels and specify pod selectors for the network policy.

    Note

    If you do not set the pod selector, the network policy applies to all pods in the specified namespace.

    In this example, the following settings are used:

    • Type: Deployment

    • Workload: nginx

    • Label: app=nginx

    Source

    Each network policy can include a whitelist of allowed ingress rules. Each rule allows network traffic that matches both the source and port sections.

    • Rule:

      • podSelector: selects pods in the same namespace as the network policy and allows inbound traffic from these pods.

      • namespaceSelector: selects pods from the specified namespaces and allows inbound traffic from these pods.

      • ipBlock: selects the specified CIDR blocks and allows inbound traffic from these CIDR blocks.

    • Port: TCP and UDP are supported.

    Note
    • If you do not add rules, no pods are allowed to access the pods to which the network policy applies.

    • If DataPath V2 or IPVLAN is enabled for the cluster, you need to use the podSelector selector instead of the ipBlock selector to limit the pods that are allowed to access the pods to which the network policy applies.

    In this example, no ingress rules are added.

    Destination

    Each network policy can include a whitelist of allowed egress rules. Each rule allows network traffic that matches both the destination and port sections.

    • Rule:

      • podSelector: selects pods in the same namespace as the network policy and allows outbound traffic to these pods.

      • namespaceSelector: selects pods from the specified namespaces and allows outbound traffic to these pods.

      • ipBlock: selects the specified CIDR blocks and allows outbound traffic to these CIDR blocks.

    • Port: TCP and UDP are supported.

    Note

    If DataPath V2 or IPVLAN is enabled for the cluster, you need to use the podSelector selector instead of the ipBlock selector to limit the pods that can be accessed to access the pods to which the network policy applies.

    In this example, no egress rules are added.

  4. Click Next. Then, click OK.

  5. Run the wget nginx command on the terminal of the busybox pod to test the accessibility of the nginx Service. For more information, see Step 5.

    The connection timed out because the network policy does not allow access from the busybox pod.

    timeout

  6. Modify the network policy to allow access from the busybox pod.

    1. On the NetworkPolicies page, find the access-nginx network policy and click Edit in the Actions column.

    2. Add an ingress rule.

      Click + Add to the right of Source, and then perform the following steps:

      • Click + Add to the right of Rule. The following table describes the rule parameters.

        Parameter

        Example

        Selector

        podSelector

        Type

        Deployment

        Workload

        busybox

        Labels

        app=busybox

      • Click + Add to the right of Port. The following table describes the port parameters.

        Parameter

        Example

        Protocol

        TCP

        Port

        80

    3. Click Next, and then click OK.

    4. Run the wget -O /dev/null nginx command to test the accessibility of the nginx Service from the busybox pod after the network policy is modified.

      After the ingress rule is added to the network policy, the busybox pod can access the nginx Service.正常访问

Use the CLI

  1. Run the vim policy.yaml command to create a file named policy.yaml with the following YAML template.

    vim policy.yaml

    The following code block shows the content of the YAML template:

    kind: NetworkPolicy
    apiVersion: networking.k8s.io/v1
    metadata:
      name: access-nginx
    spec:
      podSelector:
        matchLabels:
          run: nginx
      ingress:
      - from:
        - podSelector:
            matchLabels:
              access: "true"
  2. Run the following command to create a network policy by using the preceding policy.yaml file:

    kubectl apply -f policy.yaml 

    Expected output:

    networkpolicy.networking.k8s.io/access-nginx created
  3. Run the following command to access the nginx Service. A connection timeout error is returned because the pod does not have the specified label:

    kubectl run busybox --rm -ti --image=busybox /bin/sh

    Test the accessibility of the nginx Service:

    wget nginx

    Expected output:

    Connecting to nginx (172.19.XX.XX:80)
    wget: can't connect to remote host (172.19.XX.XX): Connection timed out
  4. Run the following command to add the specified label to the pod:

    kubectl run busybox --rm -ti --labels="access=true" --image=busybox /bin/sh

    Test the accessibility of the nginx Service:

    wget nginx

    Expected output:

    Connecting to nginx (172.21.XX.XX:80)
    saving to 'index.html'
    index.html           100% |****************************************************************************************************************************************************|   612  0:00:00 ETA
    'index.html' saved

    The output shows that the progress of the connection is 100%. This indicates that the pod can access the nginx Service as expected.

Scenario 2: Allow only specific source IP addresses to access a Service through an Internet-facing SLB instance

Use the ACK console

  1. Create a network policy for the nginx Service. For more information, see Allow only applications with specific labels to access a Service.

  2. On the Services page, find the nginx Service and copy its IP address (47.xxx.xx.x) in the External Endpoint column. Access the IP address in your browser.en

    The nginx Service cannot be accessed due to the preconfigured network policy.

  3. Modify the network policy to allow specific IP addresses to access the Service.

    1. Visit myip.ipip.net in your browser to obtain the IP address of your on-premises machine.

    2. On the NetworkPolicies page, find the access-nginx network policy and click Edit in the Actions column. Add an ingress rule in the Edit panel.

      Click + Add to the right of Source, and then perform the following steps:

      • Click + Add to the right of Rule. Add the IP address of your on-premises machine to the rule.

        Parameter

        Example

        Selector

        ipBlock

        cidr

        <IP address of your on-premises machine>/32

        Example: 42.xx.xx.xx/32.

      • Click + Add to the right of Rule. Add the CIDR block used for Server Load Balancer (SLB) health checks to the rule.

        Parameter

        Example

        Selector

        ipBlock

        cidr

        100.0.0.0/8

      • Click + Add to the right of Port. The following table describes the port parameters.

        Parameter

        Example

        Protocol

        TCP

        Port

        80

      ipblock

    3. Click Next, and then click OK.

    4. On the Services page, find the nginx Service and click the IP address (47.xxx.xx.x:80) in the External Endpoint column.

      image.png

      After the network policy is modified, the nginx Service can be accessed through an Internet-facing SLB instance from an on-premises machine.

Use the CLI

  1. Run the following command to create an SLB instance for the preceding nginx application. Set the Service type to LoadBalancer to make the application accessible over the Internet.

    vim nginx-service.yaml

    In this example, a file named nginx-service.yaml is used.

    # Copy the following YAML content to the nginx-service.yaml file: 
    apiVersion: v1
    kind: Service
    metadata:
      labels:
        run: nginx
      name: nginx-slb
    spec:
      externalTrafficPolicy: Local
      ports:
      - port: 80
        protocol: TCP
        targetPort: 80
      selector:
        run: nginx
      type: LoadBalancer

    Run the following command to create a network policy by using the nginx-service.yaml file:

    kubectl apply -f nginx-service.yaml 

    Expected output:

    service/nginx-slb created

    Check whether the application is exposed by using the nginx Service:

    kubectl get service nginx-slb

    Expected output:

    NAME        TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)        AGE
    nginx-slb   LoadBalancer   172.19.xx.xxx   47.110.xxx.xxx   80:32240/TCP   8m
  2. Run the following command to connect to the IP address of the created SLB instance: 47.110.xxx.xxx. The output shows that the connection failed.

    wget 47.110.xxx.xxx

    Expected output:

    --2018-11-21 11:46:05--  http://47.110.xx.xxx/
    Connecting to 47.110.XX.XX:80... failed: Connection refused.
    Note

    The connection failed due to the following reasons:

    • The nginx Service can be accessed only by applications that have the access=true label.

    • When you connect to the IP address of the SLB instance from your on-premises machine, you are accessing the nginx Service from outside the Kubernetes cluster. This is not the same as when you use a network policy to allow only applications with specified labels to access the nginx Service.

    Solution: Modify the network policy to allow the source IP address to access the nginx Service.

  3. Run the following command to query the IP address of your on-premises machine:

    curl myip.ipip.net

    Expected output:

    IP address: 10.0.x.x. From: China Beijing Beijing        # This is an example. Use the actual IP address.

  4. Run the following command to modify the policy.yaml file:

    vim policy.yaml

    Example of the policy.yaml file:

    # The following content is an example of the YAML file. 
    kind: NetworkPolicy
    apiVersion: networking.k8s.io/v1
    metadata:
      name: access-nginx
    spec:
      podSelector:
        matchLabels:
          run: nginx
      ingress:
      - from:
        - podSelector:
            matchLabels:
              access: "true"
        - ipBlock:
            cidr: 100.64.0.0/10
        - ipBlock:
            cidr: 10.0.0.1/24      # This is an example. Use the actual IP address.

    Run the following command to create a network policy by using the preceding policy.yaml file:

    kubectl apply -f policy.yaml 

    Expected output:

    networkpolicy.networking.k8s.io/access-nginx unchanged
    Note
    • The request may come from different IP addresses. Therefore, specify a CIDR block with a mask length of 24.

    • The IP addresses used by SLB for health checks are within the 100.64.0.0/10 CIDR block. Therefore, make sure that you add 100.64.0.0/10 to the rule.

  5. Run the following command to create the resources that are provisioned for the nginx Service:

    kubectl run busybox --rm -ti --labels="access=true" --image=busybox /bin/sh

    Access the nginx Service:

    wget 47.110.XX.XX

    Expected output:

    Connecting to 47.110.XX.XX (47.110.XX.XX:80)
    index.html           100% |***********************************************************|   612  0:00:00 ETA

    If the output shows 100%, this indicates that the nginx Service can be accessed.

Scenario 3: Allow a pod to access a specific address

Use the ACK console

In this section, www.aliyun.com and registry.aliyuncs.com are used as examples. The network policy allows a pod to access only registry.aliyuncs.com.

  1. Use the Ping command to query the IP address (120.55.XXX.XXX) to which the registry.aliyuncs.com domain name is resolved.

  2. Create a network policy and add an egress rule to allow the busybox application to access only registry.aliyuncs.com.

    1. In the upper-right corner of the NetworkPolicies page, click Create. In the Create panel, set the parameters.

    2. For more information about the parameters, see Allow only applications with specific labels to access a Service. The following table provides a sample configuration.

      Parameter

      Description

      Example

      Parameter

      Specify a custom network policy name.

      busybox-policy

      Pod Selectors

      Click + Specify workload type and labels and specify pod selectors for the network policy.

      Note

      If you do not set the pod selector, the network policy applies to all pods in the specified namespace.

      In this example, the following settings are used:

      • Type: Deployment

      • Workload: busybox

      • Label: app=busybox

      Destination

      Click + Add to the right of Destination. Then, click + Add to the right of Rule.

      Select ipBlock and add the IP address to which registry.aliyuncs.com is resolved. In this example, the IP address is 120.55.XXX.XXX/32.

      • Selector: ipBlock

      • CIDR: 120.55.XXX.XXX/32

      image.png

      Click + Add to the right of Destination. Select namespaceSelector and allow outbound traffic to pods in all namespaces through UDP port 53. This ensures that the application can perform DNS lookups.

      • Click + Add to the right of Rule. The following table describes the rule that selects all namespaces.

      • Click + Add to the right of Port. Add UDP port 53 to ensure that the application can perform DNS lookups.

      • Rules:

        • Selector: namespaceSelector

        • Namespace: All

      • Port:

        • Protocol: UDP

        • Port: 53

      image

    3. Click Next, and then click OK.

    4. Go to the terminal of the busybox pod and run the following commands to access www.aliyun.com and registry.aliyuncs.com in sequence:

      nc -vz -w 1 www.aliyunc.com 443
      nc -vz -w 1 registry.aliyuncs.com 443

      After the network policy is added, the busybox application can access only registry.aliyuncs.com.dns

Use the CLI

  1. Run the following command to query the IP addresses to which www.aliyun.com is resolved:

    dig +short www.aliyun.com

    Expected output:

    www-jp-de-intl-adns.aliyun.com.
    www-jp-de-intl-adns.aliyun.com.gds.alibabadns.com.
    v6wagbridge.aliyun.com.
    v6wagbridge.aliyun.com.gds.alibabadns.com.
    106.XX.XX.21
    140.XX.XX.4
    140.XX.XX.13
    140.XX.XX.3
  2. Run the following command to create a file named busybox-policy:

    vim busybox-policy.yaml

    Example of the busybox-policy file:

    # The following content is a sample YAML file. 
    kind: NetworkPolicy
    apiVersion: networking.k8s.io/v1
    metadata:
      name: busybox-policy
    spec:
      podSelector:
        matchLabels:
          run: busybox
      egress:
      - to:
        - ipBlock:
            cidr: 106.XX.XX.21/32
        - ipBlock:
            cidr: 140.XX.XX.4/32
        - ipBlock:
            cidr: 140.XX.XX.13/32
        - ipBlock:
            cidr: 140.XX.XX.3/32
      - to:
        - ipBlock:
            cidr: 0.0.0.0/0
        - namespaceSelector: {}
        ports:
        - protocol: UDP
          port: 53
    Note

    Egress rules are configured in the busybox-policy file to limit outbound access from the application. You must allow the application to access UDP port 53. Otherwise, Domain Name System (DNS) resolution does not work.

  3. Run the following command to create a network policy based on the busybox-policy file:

    kubectl apply -f busybox-policy.yaml 

    Expected output:

    networkpolicy.networking.k8s.io/busybox-policy created
  4. Run the following command to create the busybox application:

    kubectl run busybox --rm -ti --image=busybox /bin/sh

    Access a website other than www.aliyun.com, such as www.taobao.com:

    wget www.taobao.com

    Expected output:

    Connecting to www.taobao.com (64.13.XX.XX:80)
    wget: can't connect to remote host (64.13.XX.XX): Connection timed out

    The output shows the can't connect to remote host message. This indicates that the application failed to access the domain name.

  5. Run the following command to access www.aliyun.com:

    wget www.aliyun.com

    Expected output:

    Connecting to www.aliyun.com (140.205.XX.XX:80)
    Connecting to www.aliyun.com (140.205.XX.XX:443)
    wget: note: TLS certificate validation not implemented
    index.html           100% |***********************************************************|  462k  0:00:00 ETA

    The output shows that the progress of the connection is 100%. This indicates that the application can access the domain name as expected.

Scenario 4: Control pod access to the Internet in specific namespaces

Note

The operations in this section may affect services that communicate with the Internet. We recommend that you create an empty namespace to perform the following operations.

Use the ACK console

  1. In the upper-right corner of the NetworkPolicies page, click Create. In the Create panel, set the parameters.

    For more information about the parameters, see Allow only applications with specific labels to access a Service. The following table provides a sample configuration.

    Parameter

    Example

    Parameter

    deny-public-net

    Pod Selectors

    Set Type to All.

    Source

    Add the following ingress rules:

    • Set namespaceSelector to All.

    • Set ipBlock to 0.0.0.0/0.

    来源

    Destination

    Add egress rules that allow the pod to access only the internal network.

    • Set namespaceSelector to All. This allows the pod to access all other pods in the internal network.

    • Create three rules and set ipBlock to the following CIDR blocks in sequence:

      • 10.0.0.0/8

      • 172.16.0.0/12

      • 192.168.0.0/16

      Note

      You cannot specify multiple CIDR blocks for the ipBlock parameter in one rule.

      公网 去向

  2. Click Next, and then click OK.

  3. On the Basic Information tab of the cluster details page, obtain the private IP address and port.

    image.png

  4. Run the following command on the terminal of the busybox pod to test whether the pod can access the Internet and the internal network:

    nc -vz -w 1 www.aliyunc.com 443
    nc -vz -w 1 10.xx.xx.xx:<IP port> # Specify the private IP address.

    The output shows that the pod can access the internal network but not the Internet.Pod公网访问

Use the CLI

  1. Run the following command to create a namespace for testing.

    Create a namespace named test-np.

    kubectl create ns test-np

    Expected output:

    namespace/test-np created
  2. Run the following command to create a default network policy that allows pods in the test-np namespace to access only internal services:

    vim default-deny.yaml

    Example of the default-deny.yaml file:

    # The following content is a sample YAML file. 
    kind: NetworkPolicy
    apiVersion: networking.k8s.io/v1
    metadata:
      namespace: test-np
      name: deny-public-net
    spec:
      podSelector: {}
      ingress:
      - from:
        - ipBlock:
            cidr: 0.0.0.0/0
      egress:
      - to:
        - ipBlock:
            cidr: 192.168.0.0/16
        - ipBlock:
            cidr: 172.16.0.0/12
        - ipBlock:
            cidr: 10.0.0.0/8

    Check whether a network policy is created by using the default-deny.yaml file.

    kubectl apply -f default-deny.yaml

    Expected output:

    networkpolicy.networking.k8s.io/deny-public-net created

    View the network policy:

    kubectl get networkpolicy -n test-np

    Expected output:

    NAME                              POD-SELECTOR          AGE
    deny-public-net                   <none>                1m
  3. Run the following command to allow pods with specific labels to access the Internet.

    vim allow-specify-label.yaml

    In this example, the public-network=true label is used.

    # The following content is a sample YAML file. 
    kind: NetworkPolicy
    apiVersion: networking.k8s.io/v1
    metadata:
      name: allow-public-network-for-labels
      namespace: test-np
    spec:
      podSelector:
        matchLabels:
          public-network: "true"
      ingress:
      - from:
        - ipBlock:
            cidr: 0.0.0.0/0
      egress:
      - to:
        - ipBlock:
            cidr: 0.0.0.0/0
        - namespaceSelector:
            matchLabels:
              ns: kube-system

    Run the following command to create the network policy:

    kubectl apply -f allow-specify-label.yaml

    Expected output:

    networkpolicy.networking.k8s.io/allow-public-network-for-labels created

    View the network policy:

    kubectl get networkpolicy -n test-np

    Expected output:

    NAME                              POD-SELECTOR          AGE
    allow-public-network-for-labels   public-network=true    1m
    deny-public-net                   <none>                 3m
  4. Run the following command to verify that a pod without the specified label cannot access the Internet:

    kubectl run -it --namespace test-np --rm --image busybox  busybox-intranet
    ping aliyun.com

    Expected output:

    PING aliyun.com (106.11.2xx.xxx): 56 data bytes
    ^C
    --- aliyun.com ping statistics ---
    9 packets transmitted, 0 packets received, 100% packet loss

    The output shows 0 packets received. This indicates that the pod failed to access the Internet.

    Note

    The pod failed to access the Internet because the deny-public-net network policy does not allow pods in the test-np namespace to access the Internet. Therefore, pods with default labels cannot access the Internet.

  5. Run the following command to verify that a pod with the public-network=true label can access the Internet:

    kubectl run -it --namespace test-np --labels public-network=true --rm --image busybox  busybox-internet
    ping aliyun.com

    Expected output:

    PING aliyun.com (106.11.1xx.xx): 56 data bytes
    64 bytes from 106.11.1xx.xx: seq=0 ttl=47 time=4.235 ms
    64 bytes from 106.11.1xx.xx: seq=1 ttl=47 time=4.200 ms
    64 bytes from 106.11.1xx.xx: seq=2 ttl=47 time=4.182 ms
    ^C
    --- aliyun.com ping statistics ---
    3 packets transmitted, 3 packets received, 0% packet loss
    round-trip min/avg/max = 4.182/4.205/4.235 ms

    The output shows 0% packet loss. This indicates that the pod can access the Internet.

    Note

    The pod can access the Internet because the allow-public-network-for-labels network policy allows pods with the public-network=true label to access the Internet. The busybox-internet pod has this label and therefore can access the Internet.