Unexpected inbound connection source

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Event Information

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Meaning

• The Unexpected inbound connection source event in a Kubernetes cluster indicates that a network connection was established from an unexpected source to a pod or service within the cluster.
• This event could potentially indicate a security breach or unauthorized access attempt, as it suggests that a connection was made from an external source that is not whitelisted or expected.
• To investigate this event, you can use kubectl commands to check the network policies, pod logs, and cluster firewall rules to identify any potential misconfigurations or security vulnerabilities. For example, you can use “kubectl get networkpolicies” to list the network policies in the cluster and “kubectl logs <pod-name>” to view the logs of the affected pod.

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Remediation

1. Identify the affected pod(s) by checking the source IP address mentioned in the event.

   • Use the following command to filter the pods based on the source IP address:

     kubectl get pods -o json | jq '.items[] | select(.status.podIP == "<source_ip>") | .metadata.name'
     

   • Replace <source_ip> with the actual source IP address mentioned in the event.

2. Update the affected pod(s) by adding a network policy to block inbound connections from the identified source IP address.

   • Create a YAML file named network-policy.yaml with the following content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: block-inbound-connections
     spec:
       podSelector:
         matchLabels:
           app: <app_label>
       policyTypes:
         - Ingress
       ingress:
         - from:
             - ipBlock:
                 cidr: <source_ip>/32
     

   • Replace <app_label> with the label of the affected application.
   • Replace <source_ip> with the actual source IP address mentioned in the event.

3. Apply the network policy to the cluster to block inbound connections from the identified source IP address.

   • Run the following command to apply the network policy:

     kubectl apply -f network-policy.yaml
     

   • This will enforce the network policy on the cluster and block inbound connections from the specified source IP address to the affected pod(s).