The Linux Foundation CKS 시험

Question No : 1

CORRECT TEXT
Create a new ServiceAccount named backend-sa in the existing namespace default, which has the capability to list the pods inside thenamespace default.
Create a new Pod named backend-pod in the namespace default, mount the newly created sa backend-sa to the pod, and Verify that the pod is able to list pods.
Ensure that the Pod is running.

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정답: A service account provides an identity for processes that run in a Pod.
When you (a human) access the cluster (for example, using kubectl), you are authenticated by the apiserver as a particular User Account (currently this is usually admin,unless your cluster administrator has customized your cluster). Processes in containers inside pods can also contact the apiserver. When they do, they are authenticated as a particular Service
Account (for example, default).
When you create a pod, if youdo not specify a service account, it is automatically assigned the default service account in the same namespace. If you get the raw json or yaml for a pod you have created (for example, kubectl get pods/<podname> -o yaml), you can see the spec.serviceAccountName field has been automatically set.
You can access the API from inside a pod using automatically mounted service account credentials, as described in Accessing the Cluster. The API permissions of the service account depend on the authorization plugin and policy in use.
In version 1.6+, you can opt out of automounting API credentials for a service account by setting automountServiceAccountToken: false on the service account: apiVersion:v1
kind:ServiceAccount
metadata:
name:build-robot
automountServiceAccountToken:false
In version 1.6+, you can also opt out of automounting API credentials for a particular pod:
apiVersion:v1
kind:Pod
metadata:
name:my-pod
spec:
serviceAccountName:build-robot
automountServiceAccountToken:false
The pod spec takes precedence over the service account if both specify a automountServiceAccountToken value.

Question No : 2

CORRECT TEXT
Using the runtime detection tool Falco, Analyse the container behavior for at least 30 seconds, using filters that detect newly spawning and executing processes store the incident file art /opt/falco-incident.txt, containing the detected incidents. one per line, in the format
[timestamp],[uid],[user-name],[processName]

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Question No : 3

Create the Pod using this manifest

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정답: [desk@cli] $ ssh worker1[worker1@cli] $apparmor_parser -q /etc/apparmor.d/nginx[worker1@cli] $aa-status | grep nginxnginx-profile-1[worker1@cli] $ logout[desk@cli] $vim nginx-deploy.yamlAdd these lines under metadata:annotations: # Add this line container.apparmor.security.beta.kubernetes.io/<container-name>: localhost/nginx-profile-1[desk@cli] $kubectl apply -f nginx-deploy.yaml
Explanation[desk@cli] $ ssh worker1[worker1@cli] $apparmor_parser -q /etc/apparmor.d/nginx[worker1@cli] $aa-status | grep nginxnginx-profile-1[worker1@cli] $ logout[desk@cli] $vim nginx-deploy.yaml



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Description automatically generated

Question No : 4

CORRECT TEXT
Fix all issues via configuration and restart the affected components to ensure the new setting takes effect.
Fix all of the following violations that were found against the API server:-
✑ a. Ensure that the RotateKubeletServerCertificate argumentissettotrue.
✑ b. Ensure that the admission control plugin PodSecurityPolicyisset.
✑ c. Ensure that the --kubelet-certificate-authority argumentissetasappropriate.
Fix all of the following violations that were found against the Kubelet:-
✑ a. Ensure the --anonymous-auth argumentissettofalse.
✑ b. Ensure that the --authorization-mode argumentissetto Webhook.
Fix all of the following violations that were found against the ETCD:-
✑ a. Ensure that the --auto-tls argumentisnotsettotrue
✑ b. Ensure that the --peer-auto-tls argumentisnotsettotrue
Hint: Take the use of Tool Kube-Bench

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정답: Fix all of thefollowing violations that were found against the API server:-
✑ a. Ensure that the RotateKubeletServerCertificate argumentissettotrue.
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
component:kubelet
tier: control-plane
name: kubelet
namespace: kube-system
spec:
containers:
- command:
- kube-controller-manager
+ - --feature-gates=RotateKubeletServerCertificate=true image: gcr.io/google_containers/kubelet-amd64:v1.6.0 livenessProbe:
failureThreshold: 8 httpGet:
host: 127.0.0.1
path: /healthz
port: 6443
scheme: HTTPS
initialDelaySeconds: 15
timeoutSeconds: 15
name:kubelet
resources:
requests:
cpu: 250m
volumeMounts:
- mountPath: /etc/kubernetes/ name: k8s
readOnly: true
- mountPath: /etc/ssl/certs name: certs
- mountPath: /etc/pki name:pki hostNetwork: true volumes:
- hostPath:
path: /etc/kubernetes
name: k8s
- hostPath:
path: /etc/ssl/certs
name: certs
- hostPath: path: /etc/pki name: pki
✑ b. Ensure that theadmission control plugin PodSecurityPolicyisset.
audit: "/bin/ps -ef | grep $apiserverbin | grep -v grep"
tests:
test_items:
- flag: "--enable-admission-plugins"
compare:
op: has
value:"PodSecurityPolicy"
set: true
remediation: |
Follow the documentation and create Pod Security Policy objects as per your environment. Then, edit the API server pod specification file $apiserverconf
on themaster node and set the --enable-admission-plugins parameter to a
value that includes PodSecurityPolicy :
--enable-admission-plugins=...,PodSecurityPolicy,...
Then restart the API Server.
scored: true
✑ c. Ensure thatthe --kubelet-certificate-authority argumentissetasappropriate.
audit: "/bin/ps -ef | grep $apiserverbin | grep -v grep"
tests:
test_items:
- flag: "--kubelet-certificate-authority" set: true
remediation: |
Follow the Kubernetes documentation and setup the TLS connection between the apiserver and kubelets. Then, edit the API server pod specification file $apiserverconf on the master node and set the --kubelet-certificate-authority parameter to the path to the cert file for the certificate authority. --kubelet-certificate-authority=<ca-string>
scored: true
Fix all of the following violations that were found against the ETCD:-
✑ a. Ensurethat the --auto-tls argumentisnotsettotrue
Edit the etcd pod specification file $etcdconf on the masternode and either remove the -- auto-tls parameter or set it to false.--auto-tls=false
✑ b. Ensure that the --peer-auto-tls argumentisnotsettotrue
Edit the etcd pod specification file $etcdconf on the masternode and either remove the -- peer-auto-tls parameter or set it to false.--peer-auto-tls=false

Question No : 5

sysdig
Tools are pre-installed on the worker1 node only.
Analyse the container’s behaviour for at least 40 seconds, using filters that detect newly spawning and executing processes.
Store an incident file at /home/cert_masters/report, in the following format:
[timestamp],[uid],[processName]
Note: Make sure to store incident file on the cluster's worker node, don't move it to master node.

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정답: $vim /etc/falco/falco_rules.local.yaml
✑ uk.co.certification.simulator.questionpool.PList@dd92f60 $kill -1 <PID of falco>
Explanation[desk@cli] $ ssh node01[node01@cli] $ vim /etc/falco/falco_rules.yamlsearch for Container Drift Detected & paste in falco_rules.local.yaml[node01@cli] $ vim /etc/falco/falco_rules.local.yaml
- rule: Container Drift Detected (open+create)
desc: New executable created in a container due to open+create
condition: >
evt.type in (open,openat,creat) and
evt.is_open_exec=true and
container and
not runc_writing_exec_fifo and
not runc_writing_var_lib_docker and
not user_known_container_drift_activities and
evt.rawres>=0
output: >
%evt.time,%user.uid,%proc.name # Add this/Refer falco documentation priority: ERROR
[node01@cli] $ vim /etc/falco/falco.yaml

Question No : 6

CORRECT TEXT
On the Cluster worker node, enforce the prepared AppArmor profile
✑ #include<tunables/global>
✑
✑ profilenginx-deny flags=(attach_disconnected) {
✑ #include<abstractions/base>
✑
✑ file,
✑
✑ # Deny all file writes.
✑ deny/** w,
✑ }
✑ EOF'
Edit the prepared manifest file to include the AppArmor profile.
✑ apiVersion: v1
✑ kind: Pod
✑ metadata:
✑ name:apparmor-pod
✑ spec:
✑ containers:
✑ - name: apparmor-pod
✑ image: nginx
Finally, apply the manifests files and create the Pod specified on it.
Verify: Try to make a file inside the directory which is restricted.

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Question No : 7

CORRECT TEXT
Cluster: scanner
Master node: controlplane
Worker node: worker1
You can switch the cluster/configuration context using the following command:
[desk@cli] $ kubectl config use-context scanner
Given:
You may use Trivy's documentation.
Task:
Use the Trivy open-source container scanner to detect images with severe vulnerabilities used by Pods in the namespace nato.
Look for images with High or Critical severity vulnerabilities and delete the Pods that use those images.
Trivy is pre-installed on the cluster's master node. Use cluster's master node to use Trivy.

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정답: [controlplane@cli] $ k get pods -n nato -o yaml | grep "image: "[controlplane@cli] $ trivy image <image-name>[controlplane@cli] $ k delete pod <vulnerable-pod> -n nato
[desk@cli] $ ssh controlnode[controlplane@cli] $ k get pods -n nato
NAME READY STATUS RESTARTS AGE
alohmora 1/1 Running 0 3m7s
c3d3 1/1 Running 0 2m54s
neon-pod 1/1 Running 0 2m11s
thor 1/1 Running 0 58s
[controlplane@cli] $ k get pods -n nato -o yaml | grep "image: "



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Description automatically generated[controlplane@cli] $ trivy image <image-name>



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Description automatically generated
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Description automatically generatedNote: As there are 2 images have vulnerability with severity Hight & Critical. Delete containers for nginx:latest & alpine:3.7 [controlplane@cli] $ k delete pod thor -n nato

Question No : 8

Pods being configured to be privileged in any way must be treated as potentially not stateless or not immutable.

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정답: k get pods -n prodk get pod <pod-name> -n prod -o yaml | grep -E 'privileged|ReadOnlyRootFileSystem'Delete the pods which do have any of these 2 propertiesprivileged:true or ReadOnlyRootFileSystem: false
[desk@cli]$ k get pods -n prod
NAME READY STATUS RESTARTS AGE
cms 1/1 Running 0 68m
db 1/1 Running 0 4m
nginx 1/1 Running 0 23m
[desk@cli]$ k get pod nginx -n prod -o yaml | grep -E 'privileged|RootFileSystem' {"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"creationTimestamp":null,"label s":{"run":"nginx"},"name":"nginx","namespace":"prod"},"spec":{"containers":[{"image":"nginx ","name":"nginx","resources":{},"securityContext":{"privileged":true }}],"dnsPolicy":"ClusterFirst","restartPolicy":"Always"},"status":{}}f:privileged: {}privileged:
true



[desk@cli]$ k delete pod nginx -n prod
[desk@cli]$ k get pod db -n prod -o yaml | grep -E 'privileged|RootFilesystem'



[desk@cli]$ k get pod cms -n prod -o yaml | grep -E 'privileged|RootFilesystem'

Question No : 9

CORRECT TEXT
Create a RuntimeClass named untrusted using the prepared runtime handler named runsc.
Create a Pods of image alpine:3.13.2 in the Namespace default to run on the gVisor runtime class.
Verify: Exec the pods and run the dmesg, you will see output like this:-

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Question No : 10

CORRECT TEXT
a. Retrieve the content of the existing secret named default-token-xxxxx in the testing namespace.
Store the value of the token in thetoken.txt
b. Create a new secret named test-db-secret in the DB namespace with the following content:
username: mysql
password: password@123
Create the Pod name test-db-pod of image nginx in the namespace db that can accesstest-db-secret via a volume at path /etc/mysql-credentials

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정답: To add a Kubernetes cluster to your project, group, or instance:
✑ Navigate to your:
✑ Click Add Kubernetes cluster.
✑ Click the Add existing cluster tab and fill in the details:
Get the API URL by running this command:
kubectl cluster-info | grep-E'Kubernetes master|Kubernetes control plane'| awk'/http/ {print $NF}'
✑ uk.co.certification.simulator.questionpool.PList@dd80600
kubectl get secret <secret name>-ojsonpath="{['data']['ca\.crt']}"