Linux Foundation CKS試験問題（更新されたのは2024年）100%リアル問題解答 [Q14-Q32]

Linux Foundation CKS試験問題（更新されたのは2024年）100%リアル問題解答

合格させるLinux Foundation CKS試験最速合格

質問 # 14
Context: Cluster: prod Master node: master1 Worker node: worker1
You can switch the cluster/configuration context using the following command:
[desk@cli] $ kubectl config use-context prod
Task: Analyse and edit the given Dockerfile (based on the ubuntu:18:04 image) /home/cert_masters/Dockerfile fixing two instructions present in the file being prominent security/best-practice issues.
Analyse and edit the given manifest file /home/cert_masters/mydeployment.yaml fixing two fields present in the file being prominent security/best-practice issues.
Note: Don't add or remove configuration settings; only modify the existing configuration settings, so that two configuration settings each are no longer security/best-practice concerns. Should you need an unprivileged user for any of the tasks, use user nobody with user id 65535

正解：

解説：
1. For Dockerfile: Fix the image version & user name in Dockerfile 2. For mydeployment.yaml : Fix security contexts Explanation
[desk@cli] $ vim /home/cert_masters/Dockerfile
FROM ubuntu:latest # Remove this
FROM ubuntu:18.04 # Add this
USER root # Remove this
USER nobody # Add this
RUN apt get install -y lsof=4.72 wget=1.17.1 nginx=4.2
ENV ENVIRONMENT=testing
USER root # Remove this
USER nobody # Add this
CMD ["nginx -d"]

[desk@cli] $ vim /home/cert_masters/mydeployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
labels:
app: kafka
name: kafka
spec:
replicas: 1
selector:
matchLabels:
app: kafka
strategy: {}
template:
metadata:
creationTimestamp: null
labels:
app: kafka
spec:
containers:
- image: bitnami/kafka
name: kafka
volumeMounts:
- name: kafka-vol
mountPath: /var/lib/kafka
securityContext:
{"capabilities":{"add":["NET_ADMIN"],"drop":["all"]},"privileged": True,"readOnlyRootFilesystem": False, "runAsUser": 65535} # Delete This
{"capabilities":{"add":["NET_ADMIN"],"drop":["all"]},"privileged": False,"readOnlyRootFilesystem": True, "runAsUser": 65535} # Add This resources: {} volumes:
- name: kafka-vol
emptyDir: {}
status: {}
Pictorial View: [desk@cli] $ vim /home/cert_masters/mydeployment.yaml

質問 # 15
Cluster: admission-cluster
Master node: master
Worker node: worker1
You can switch the cluster/configuration context using the following command:
[desk@cli] $ kubectl config use-context admission-cluster
Context:
A container image scanner is set up on the cluster, but it's not yet fully integrated into the cluster's configuration. When complete, the container image scanner shall scan for and reject the use of vulnerable images.
Task:
You have to complete the entire task on the cluster's master node, where all services and files have been prepared and placed.
Given an incomplete configuration in directory /etc/Kubernetes/config and a functional container image scanner with HTTPS endpoint https://imagescanner.local:8181/image_policy:
1. Enable the necessary plugins to create an image policy
2. Validate the control configuration and change it to an implicit deny
3. Edit the configuration to point to the provided HTTPS endpoint correctly Finally, test if the configuration is working by trying to deploy the vulnerable resource /home/cert_masters/test-pod.yml Note: You can find the container image scanner's log file at /var/log/policy/scanner.log

正解：

解説：
[master@cli] $ cd /etc/Kubernetes/config
1. Edit kubeconfig to explicity deny
[master@cli] $ vim kubeconfig.json
"defaultAllow": false # Change to false
2. fix server parameter by taking its value from ~/.kube/config
[master@cli] $cat /etc/kubernetes/config/kubeconfig.yaml | grep server
server:
3. Enable ImagePolicyWebhook
[master@cli] $ vim /etc/kubernetes/manifests/kube-apiserver.yaml
- --enable-admission-plugins=NodeRestriction,ImagePolicyWebhook # Add this
- --admission-control-config-file=/etc/kubernetes/config/kubeconfig.json # Add this Explanation
[desk@cli] $ ssh master
[master@cli] $ cd /etc/Kubernetes/config
[master@cli] $ vim kubeconfig.json
{
"imagePolicy": {
"kubeConfigFile": "/etc/kubernetes/config/kubeconfig.yaml",
"allowTTL": 50,
"denyTTL": 50,
"retryBackoff": 500,
"defaultAllow": true # Delete this
"defaultAllow": false # Add this
}
}

Note: We can see a missing value here, so how from where i can get this value
[master@cli] $cat ~/.kube/config | grep server
or
[master@cli] $cat /etc/kubernetes/manifests/kube-apiserver.yaml

[master@cli] $vim /etc/kubernetes/config/kubeconfig.yaml

[master@cli] $ vim /etc/kubernetes/manifests/kube-apiserver.yaml - --enable-admission-plugins=NodeRestriction # Delete This - --enable-admission-plugins=NodeRestriction,ImagePolicyWebhook # Add this - --admission-control-config-file=/etc/kubernetes/config/kubeconfig.json # Add this Reference: https://kubernetes.io/docs/reference/access-authn-authz/admission-controllers/
- --enable-admission-plugins=NodeRestriction # Delete This
- --enable-admission-plugins=NodeRestriction,ImagePolicyWebhook # Add this
- --admission-control-config-file=/etc/kubernetes/config/kubeconfig.json # Add this
[master@cli] $ vim /etc/kubernetes/manifests/kube-apiserver.yaml - --enable-admission-plugins=NodeRestriction # Delete This - --enable-admission-plugins=NodeRestriction,ImagePolicyWebhook # Add this - --admission-control-config-file=/etc/kubernetes/config/kubeconfig.json # Add this Reference: https://kubernetes.io/docs/reference/access-authn-authz/admission-controllers/

質問 # 16
Use the kubesec docker images to scan the given YAML manifest, edit and apply the advised changes, and passed with a score of 4 points.
kubesec-test.yaml
apiVersion: v1
kind: Pod
metadata:
name: kubesec-demo
spec:
containers:
- name: kubesec-demo
image: gcr.io/google-samples/node-hello:1.0
securityContext:
readOnlyRootFilesystem: true

A. Hint: docker run -i kubesec/kubesec:512c5e0 scan /dev/stdin < kubesec-test.yaml

正解：A

質問 # 17
Given an existing Pod named nginx-pod running in the namespace test-system, fetch the service-account-name used and put the content in /candidate/KSC00124.txt Create a new Role named dev-test-role in the namespace test-system, which can perform update operations, on resources of type namespaces.
Create a new RoleBinding named dev-test-role-binding, which binds the newly created Role to the Pod's ServiceAccount ( found in the Nginx pod running in namespace test-system).

正解：

解説：

質問 # 18
Analyze and edit the given Dockerfile
FROM ubuntu:latest
RUN apt-get update -y
RUN apt-install nginx -y
COPY entrypoint.sh /
ENTRYPOINT ["/entrypoint.sh"]
USER ROOT
Fixing two instructions present in the file being prominent security best practice issues Analyze and edit the deployment manifest file apiVersion: v1 kind: Pod metadata:
name: security-context-demo-2
spec:
securityContext:
runAsUser: 1000
containers:
- name: sec-ctx-demo-2
image: gcr.io/google-samples/node-hello:1.0
securityContext:
runAsUser: 0
privileged: True
allowPrivilegeEscalation: false
Fixing two fields present in the file being prominent security best practice issues Don't add or remove configuration settings; only modify the existing configuration settings Whenever you need an unprivileged user for any of the tasks, use user test-user with the user id 5487

A. Send us your Feedback on this.

正解：A

質問 # 19
Context
A CIS Benchmark tool was run against the kubeadm-created cluster and found multiple issues that must be addressed immediately.
Task
Fix all issues via configuration and restart the affected components to ensure the new settings take effect.
Fix all of the following violations that were found against the API server:

Fix all of the following violations that were found against the Kubelet:

Fix all of the following violations that were found against etcd:

正解：

解説：

質問 # 20
SIMULATION
Create a network policy named allow-np, that allows pod in the namespace staging to connect to port 80 of other pods in the same namespace.
Ensure that Network Policy:-
1. Does not allow access to pod not listening on port 80.
2. Does not allow access from Pods, not in namespace staging.

正解：

解説：
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: network-policy
spec:
podSelector: {} #selects all the pods in the namespace deployed
policyTypes:
- Ingress
ingress:
- ports: #in input traffic allowed only through 80 port only
- protocol: TCP
port: 80

質問 # 21
SIMULATION
Enable audit logs in the cluster, To Do so, enable the log backend, and ensure that
1. logs are stored at /var/log/kubernetes/kubernetes-logs.txt.
2. Log files are retained for 5 days.
3. at maximum, a number of 10 old audit logs files are retained.
Edit and extend the basic policy to log:
1. Cronjobs changes at RequestResponse
2. Log the request body of deployments changes in the namespace kube-system.
3. Log all other resources in core and extensions at the Request level.
4. Don't log watch requests by the "system:kube-proxy" on endpoints or

A. Send us the Feedback on it.

正解：A

質問 # 22
You can switch the cluster/configuration context using the following command:
[desk@cli] $ kubectl config use-context stage
Context:
A PodSecurityPolicy shall prevent the creation of privileged Pods in a specific namespace.
Task:
1. Create a new PodSecurityPolcy named deny-policy, which prevents the creation of privileged Pods.
2. Create a new ClusterRole name deny-access-role, which uses the newly created PodSecurityPolicy deny-policy.
3. Create a new ServiceAccount named psd-denial-sa in the existing namespace development.
Finally, create a new ClusterRoleBindind named restrict-access-bind, which binds the newly created ClusterRole deny-access-role to the newly created ServiceAccount psp-denial-sa

正解：

解説：
Create psp to disallow privileged container
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: deny-access-role
rules:
- apiGroups: ['policy']
resources: ['podsecuritypolicies']
verbs: ['use']
resourceNames:
- "deny-policy"
k create sa psp-denial-sa -n development
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: restrict-access-bing
roleRef:
kind: ClusterRole
name: deny-access-role
apiGroup: rbac.authorization.k8s.io
subjects:
- kind: ServiceAccount
name: psp-denial-sa
namespace: development
Explanation
master1 $ vim psp.yaml
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
name: deny-policy
spec:
privileged: false # Don't allow privileged pods!
seLinux:
rule: RunAsAny
supplementalGroups:
rule: RunAsAny
runAsUser:
rule: RunAsAny
fsGroup:
rule: RunAsAny
volumes:
- '*'
master1 $ vim cr1.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: deny-access-role
rules:
- apiGroups: ['policy']
resources: ['podsecuritypolicies']
verbs: ['use']
resourceNames:
- "deny-policy"
master1 $ k create sa psp-denial-sa -n development
master1 $ vim cb1.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: restrict-access-bing
roleRef:
kind: ClusterRole
name: deny-access-role
apiGroup: rbac.authorization.k8s.io
subjects:
# Authorize specific service accounts:
- kind: ServiceAccount
name: psp-denial-sa
namespace: development
master1 $ k apply -f psp.yaml master1 $ k apply -f cr1.yaml master1 $ k apply -f cb1.yaml Reference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/ master1 $ k apply -f cr1.yaml master1 $ k apply -f cb1.yaml master1 $ k apply -f psp.yaml master1 $ k apply -f cr1.yaml master1 $ k apply -f cb1.yaml Reference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/

質問 # 23
Before Making any changes build the Dockerfile with tag base:v1
Now Analyze and edit the given Dockerfile(based on ubuntu 16:04)
Fixing two instructions present in the file, Check from Security Aspect and Reduce Size point of view.
Dockerfile:
FROM ubuntu:latest
RUN apt-get update -y
RUN apt install nginx -y
COPY entrypoint.sh /
RUN useradd ubuntu
ENTRYPOINT ["/entrypoint.sh"]
USER ubuntu
entrypoint.sh
#!/bin/bash
echo "Hello from CKS"
After fixing the Dockerfile, build the docker-image with the tag base:v2

A. To Verify: Check the size of the image before and after the build.

正解：A

質問 # 24
Enable audit logs in the cluster, To Do so, enable the log backend, and ensure that
1. logs are stored at /var/log/kubernetes/kubernetes-logs.txt.
2. Log files are retained for 5 days.
3. at maximum, a number of 10 old audit logs files are retained.
Edit and extend the basic policy to log:

A. 1. Cronjobs changes at RequestResponse

正解：A

解説：
2. Log the request body of deployments changes in the namespace kube-system.
3. Log all other resources in core and extensions at the Request level.
4. Don't log watch requests by the "system:kube-proxy" on endpoints or

質問 # 25
Context
AppArmor is enabled on the cluster's worker node. An AppArmor profile is prepared, but not enforced yet.

Task
On the cluster's worker node, enforce the prepared AppArmor profile located at /etc/apparmor.d/nginx_apparmor.
Edit the prepared manifest file located at /home/candidate/KSSH00401/nginx-pod.yaml to apply the AppArmor profile.
Finally, apply the manifest file and create the Pod specified in it.

正解：

解説：

質問 # 26
SIMULATION
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]

A. Sendusyoursuggestiononit

正解：A

質問 # 27
SIMULATION
use the Trivy to scan the following images,
1. amazonlinux:1
2. k8s.gcr.io/kube-controller-manager:v1.18.6
Look for images with HIGH or CRITICAL severity vulnerabilities and store the output of the same in /opt/trivy-vulnerable.txt

A. Send us the Feedback on it.

正解：A

質問 # 28
Create a new NetworkPolicy named deny-all in the namespace testing which denies all traffic of type ingress and egress traffic

正解：

解説：
You can create a "default" isolation policy for a namespace by creating a NetworkPolicy that selects all pods but does not allow any ingress traffic to those pods.
---
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: default-deny-ingress
spec:
podSelector: {}
policyTypes:
- Ingress
You can create a "default" egress isolation policy for a namespace by creating a NetworkPolicy that selects all pods but does not allow any egress traffic from those pods.
---
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: allow-all-egress
spec:
podSelector: {}
egress:
- {}
policyTypes:
- Egress
Default deny all ingress and all egress traffic
You can create a "default" policy for a namespace which prevents all ingress AND egress traffic by creating the following NetworkPolicy in that namespace.
---
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: default-deny-all
spec:
podSelector: {}
policyTypes:
- Ingress
- Egress
This ensures that even pods that aren't selected by any other NetworkPolicy will not be allowed ingress or egress traffic.

質問 # 29
Create a RuntimeClass named gvisor-rc using the prepared runtime handler named runsc.
Create a Pods of image Nginx in the Namespace server to run on the gVisor runtime class

正解：

解説：
Install the Runtime Class for gVisor
{ # Step 1: Install a RuntimeClass
cat <<EOF | kubectl apply -f -
apiVersion: node.k8s.io/v1beta1
kind: RuntimeClass
metadata:
name: gvisor
handler: runsc
EOF
}
Create a Pod with the gVisor Runtime Class
{ # Step 2: Create a pod
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
name: nginx-gvisor
spec:
runtimeClassName: gvisor
containers:
- name: nginx
image: nginx
EOF
}
Verify that the Pod is running
{ # Step 3: Get the pod
kubectl get pod nginx-gvisor -o wide
}

質問 # 30
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 the --authorization-mode argument includes RBAC b. Ensure the --authorization-mode argument includes Node c. Ensure that the --profiling argument is set to false Fix all of the following violations that were found against the Kubelet:- a. Ensure the --anonymous-auth argument is set to false.
b. Ensure that the --authorization-mode argument is set to Webhook.
Fix all of the following violations that were found against the ETCD:-
a. Ensure that the --auto-tls argument is not set to true
Hint: Take the use of Tool Kube-Bench

正解：

解説：
API server:
Ensure the --authorization-mode argument includes RBAC
Turn on Role Based Access Control. Role Based Access Control (RBAC) allows fine-grained control over the operations that different entities can perform on different objects in the cluster. It is recommended to use the RBAC authorization mode.
Fix - Buildtime
Kubernetes
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
component: kube-apiserver
tier: control-plane
name: kube-apiserver
namespace: kube-system
spec:
containers:
- command:
+ - kube-apiserver
+ - --authorization-mode=RBAC,Node
image: gcr.io/google_containers/kube-apiserver-amd64:v1.6.0
livenessProbe:
failureThreshold: 8
httpGet:
host: 127.0.0.1
path: /healthz
port: 6443
scheme: HTTPS
initialDelaySeconds: 15
timeoutSeconds: 15
name: kube-apiserver-should-pass
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
Ensure the --authorization-mode argument includes Node
Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --authorization-mode parameter to a value that includes Node.
--authorization-mode=Node,RBAC
Audit:
/bin/ps -ef | grep kube-apiserver | grep -v grep
Expected result:
'Node,RBAC' has 'Node'
Ensure that the --profiling argument is set to false
Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the below parameter.
--profiling=false
Audit:
/bin/ps -ef | grep kube-apiserver | grep -v grep
Expected result:
'false' is equal to 'false'
Fix all of the following violations that were found against the Kubelet:- Ensure the --anonymous-auth argument is set to false.
Remediation: If using a Kubelet config file, edit the file to set authentication: anonymous: enabled to false. If using executable arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and set the below parameter in KUBELET_SYSTEM_PODS_ARGS variable.
--anonymous-auth=false
Based on your system, restart the kubelet service. For example:
systemctl daemon-reload
systemctl restart kubelet.service
Audit:
/bin/ps -fC kubelet
Audit Config:
/bin/cat /var/lib/kubelet/config.yaml
Expected result:
'false' is equal to 'false'
2) Ensure that the --authorization-mode argument is set to Webhook.
Audit
docker inspect kubelet | jq -e '.[0].Args[] | match("--authorization-mode=Webhook").string' Returned Value: --authorization-mode=Webhook Fix all of the following violations that were found against the ETCD:- a. Ensure that the --auto-tls argument is not set to true Do not use self-signed certificates for TLS. etcd is a highly-available key value store used by Kubernetes deployments for persistent storage of all of its REST API objects. These objects are sensitive in nature and should not be available to unauthenticated clients. You should enable the client authentication via valid certificates to secure the access to the etcd service.
Fix - Buildtime
Kubernetes
apiVersion: v1
kind: Pod
metadata:
annotations:
scheduler.alpha.kubernetes.io/critical-pod: ""
creationTimestamp: null
labels:
component: etcd
tier: control-plane
name: etcd
namespace: kube-system
spec:
containers:
- command:
+ - etcd
+ - --auto-tls=true
image: k8s.gcr.io/etcd-amd64:3.2.18
imagePullPolicy: IfNotPresent
livenessProbe:
exec:
command:
- /bin/sh
- -ec
- ETCDCTL_API=3 etcdctl --endpoints=https://[192.168.22.9]:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt
--cert=/etc/kubernetes/pki/etcd/healthcheck-client.crt --key=/etc/kubernetes/pki/etcd/healthcheck-client.key get foo failureThreshold: 8 initialDelaySeconds: 15 timeoutSeconds: 15 name: etcd-should-fail resources: {} volumeMounts:
- mountPath: /var/lib/etcd
name: etcd-data
- mountPath: /etc/kubernetes/pki/etcd
name: etcd-certs
hostNetwork: true
priorityClassName: system-cluster-critical
volumes:
- hostPath:
path: /var/lib/etcd
type: DirectoryOrCreate
name: etcd-data
- hostPath:
path: /etc/kubernetes/pki/etcd
type: DirectoryOrCreate
name: etcd-certs
status: {}
Explanation:

質問 # 31
Context
A container image scanner is set up on the cluster, but it's not yet fully integrated into the cluster s configuration. When complete, the container image scanner shall scan for and reject the use of vulnerable images.
Task

Given an incomplete configuration in directory /etc/kubernetes/epconfig and a functional container image scanner with HTTPS endpoint https://wakanda.local:8081 /image_policy :
1. Enable the necessary plugins to create an image policy
2. Validate the control configuration and change it to an implicit deny
3. Edit the configuration to point to the provided HTTPS endpoint correctly Finally, test if the configuration is working by trying to deploy the vulnerable resource /root/KSSC00202/vulnerable-resource.yml.