<p>I have a TCP service that runs on via a Kubernetes Deployment on an AWS EKS cluster and is exposed to the internet by a Service of type LoadBalancer using the following definition</p>

<pre><code>apiVersion: v1
kind: Service
metadata:
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-type: nlb
    service.beta.kubernetes.io/aws-load-balancer-backend-protocol: tcp
  name: tcpservice
spec:
  selector:
    app: tcpapp
  type: LoadBalancer
  ports:
  - port: 4453
    targetPort: 4453
    name: tcpport
</code></pre>

<p>Because the load balancer type is NLB, the ingress traffic has to be explicitly allowed on the security group that is applied to the nodes themselves.  The security group was created like this:</p>

<pre><code>✔ ~$ aws ec2 describe-security-groups --group-ids sg-2645567125762c6e2 | jq '.SecurityGroups[0].IpPermissions[0]'
{
  "FromPort": 32163,
  "IpProtocol": "tcp",
  "IpRanges": [
    {
      "CidrIp": "10.20.0.0/20",
      "Description": "kubernetes.io/rule/nlb/health=afd5427b6058811ea989512627425a2e"
    },
    {
      "CidrIp": "0.0.0.0/0",
      "Description": "kubernetes.io/rule/nlb/client=afd5427b6058811ea989512627425a2e"
    }
  ],
  "Ipv6Ranges": [],
  "PrefixListIds": [],
  "ToPort": 32163,
  "UserIdGroupPairs": []
}
</code></pre>

<p>So now I need to change the CidrIp in the "0.0.0.0/0" to a different block. How can I do this using kubernetes manifests? I've looked at the NetworkPolicy and Calico documentation, but this controls traffic to pods not services. I can change it with the AWS API or manually, but those changes are lost when the service is redeployed.</p>

<p>you need to add in your service manifest the loadBalancerSourceRanges parameter.</p>

<p>from documentation: </p>

<p>In order to limit which client IP’s can access the Network Load Balancer, specify loadBalancerSourceRanges.</p>

<pre><code>spec:
  loadBalancerSourceRanges:
  - "143.231.0.0/16"
</code></pre>

<p><a href="https://v1-13.docs.kubernetes.io/docs/concepts/services-networking/service/" rel="noreferrer">https://v1-13.docs.kubernetes.io/docs/concepts/services-networking/service/</a></p>

<p>how code is implemented can be found here:</p>

<p><a href="https://github.com/kubernetes/kubernetes/blob/9d6ebf6c78f406d8639aae189901e47562418071/pkg/api/service/util.go" rel="noreferrer">https://github.com/kubernetes/kubernetes/blob/9d6ebf6c78f406d8639aae189901e47562418071/pkg/api/service/util.go</a></p>
