最新的Linux Foundation Certified Kubernetes Security Specialist (CKS) - CKS免費考試真題
問題1
SIMULATION
Documentation Namespace, NetworkPolicy, Pod
You must connect to the correct host . Failure to do so may result in a zero score.
[candidate@base] $ ssh cks000031
Context
You must implement NetworkPolicies controlling the traffic flow of existing Deployments across namespaces.
Task
First, create a NetworkPolicy named deny-policy in the prod namespace to block all ingress traffic.
The prod namespace is labeled env:prod
Next, create a NetworkPolicy named allow-from-prod in the data namespace to allow ingress traffic only from Pods in the prod namespace.
Use the label of the prod names & Click to copy traffic.
The data namespace is labeled env:data
Do not modify or delete any namespaces or Pods . Only create the required NetworkPolicies.
Documentation Namespace, NetworkPolicy, Pod
You must connect to the correct host . Failure to do so may result in a zero score.
[candidate@base] $ ssh cks000031
Context
You must implement NetworkPolicies controlling the traffic flow of existing Deployments across namespaces.
Task
First, create a NetworkPolicy named deny-policy in the prod namespace to block all ingress traffic.
The prod namespace is labeled env:prod
Next, create a NetworkPolicy named allow-from-prod in the data namespace to allow ingress traffic only from Pods in the prod namespace.
Use the label of the prod names & Click to copy traffic.
The data namespace is labeled env:data
Do not modify or delete any namespaces or Pods . Only create the required NetworkPolicies.
正確答案:
See the Explanation below for complete solution
Explanation:
1) Connect to the correct host
ssh cks000031
sudo -i
2) Use admin kubeconfig (safe default)
export KUBECONFIG=/etc/kubernetes/admin.conf
PART A - Deny ALL ingress traffic in prod namespace
Requirement:
NetworkPolicy name: deny-policy
Namespace: prod (namespace is labeled env=prod)
Effect: block all ingress
3) Create deny-policy in prod
Create the policy directly with kubectl (fastest & safest):
cat <<EOF | kubectl apply -f -
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: deny-policy
namespace: prod
spec:
podSelector: {}
policyTypes:
- Ingress
EOF
✅ What this does:
podSelector: {} → selects all Pods in prod
No ingress: rules → deny all ingress traffic
4) Verify
kubectl -n prod get networkpolicy deny-policy
PART B - Allow ingress to data ONLY from Pods in prod
Requirement:
NetworkPolicy name: allow-from-prod
Namespace: data (namespace is labeled env=data)
Allow ingress only from Pods in prod namespace
Use namespace label (env=prod)
5) Create allow-from-prod policy in data
cat <<EOF | kubectl apply -f -
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: allow-from-prod
namespace: data
spec:
podSelector: {}
policyTypes:
- Ingress
ingress:
- from:
- namespaceSelector:
matchLabels:
env: prod
EOF
✅ What this does:
Applies to all Pods in data
Allows ingress only from namespaces labeled env=prod
All other ingress traffic is denied by default
6) Verify
kubectl -n data get networkpolicy allow-from-prod
FINAL CHECK (What the examiner expects)
kubectl get networkpolicy -n prod
kubectl get networkpolicy -n data
You should see:
deny-policy in prod
allow-from-prod in data
Explanation:
1) Connect to the correct host
ssh cks000031
sudo -i
2) Use admin kubeconfig (safe default)
export KUBECONFIG=/etc/kubernetes/admin.conf
PART A - Deny ALL ingress traffic in prod namespace
Requirement:
NetworkPolicy name: deny-policy
Namespace: prod (namespace is labeled env=prod)
Effect: block all ingress
3) Create deny-policy in prod
Create the policy directly with kubectl (fastest & safest):
cat <<EOF | kubectl apply -f -
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: deny-policy
namespace: prod
spec:
podSelector: {}
policyTypes:
- Ingress
EOF
✅ What this does:
podSelector: {} → selects all Pods in prod
No ingress: rules → deny all ingress traffic
4) Verify
kubectl -n prod get networkpolicy deny-policy
PART B - Allow ingress to data ONLY from Pods in prod
Requirement:
NetworkPolicy name: allow-from-prod
Namespace: data (namespace is labeled env=data)
Allow ingress only from Pods in prod namespace
Use namespace label (env=prod)
5) Create allow-from-prod policy in data
cat <<EOF | kubectl apply -f -
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: allow-from-prod
namespace: data
spec:
podSelector: {}
policyTypes:
- Ingress
ingress:
- from:
- namespaceSelector:
matchLabels:
env: prod
EOF
✅ What this does:
Applies to all Pods in data
Allows ingress only from namespaces labeled env=prod
All other ingress traffic is denied by default
6) Verify
kubectl -n data get networkpolicy allow-from-prod
FINAL CHECK (What the examiner expects)
kubectl get networkpolicy -n prod
kubectl get networkpolicy -n data
You should see:
deny-policy in prod
allow-from-prod in data
問題2
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
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
正確答案:
See the Explanation belowExplanation:
問題3
SIMULATION
Context
A Role bound to a Pod's ServiceAccount grants overly permissive permissions. Complete the following tasks to reduce the set of permissions.
Task
Given an existing Pod named web-pod running in the namespace security.
Edit the existing Role bound to the Pod's ServiceAccount sa-dev-1 to only allow performing watch operations, only on resources of type services.
Create a new Role named role-2 in the namespace security, which only allows performing update operations, only on resources of type namespaces.
Create a new RoleBinding named role-2-binding binding the newly created Role to the Pod's ServiceAccount.
Context
A Role bound to a Pod's ServiceAccount grants overly permissive permissions. Complete the following tasks to reduce the set of permissions.
Task
Given an existing Pod named web-pod running in the namespace security.
Edit the existing Role bound to the Pod's ServiceAccount sa-dev-1 to only allow performing watch operations, only on resources of type services.
Create a new Role named role-2 in the namespace security, which only allows performing update operations, only on resources of type namespaces.
Create a new RoleBinding named role-2-binding binding the newly created Role to the Pod's ServiceAccount.
正確答案:
SeetheExplanationbelowExplanation:
問題4
SIMULATION
Context
A PodSecurityPolicy shall prevent the creation of privileged Pods in a specific namespace.
Task
Create a new PodSecurityPolicy named prevent-psp-policy,which prevents the creation of privileged Pods.
Create a new ClusterRole named restrict-access-role, which uses the newly created PodSecurityPolicy prevent-psp-policy.
Create a new ServiceAccount named psp-restrict-sa in the existing namespace staging.
Finally, create a new ClusterRoleBinding named restrict-access-bind, which binds the newly created ClusterRole restrict-access-role to the newly created ServiceAccount psp-restrict-sa.
Context
A PodSecurityPolicy shall prevent the creation of privileged Pods in a specific namespace.
Task
Create a new PodSecurityPolicy named prevent-psp-policy,which prevents the creation of privileged Pods.
Create a new ClusterRole named restrict-access-role, which uses the newly created PodSecurityPolicy prevent-psp-policy.
Create a new ServiceAccount named psp-restrict-sa in the existing namespace staging.
Finally, create a new ClusterRoleBinding named restrict-access-bind, which binds the newly created ClusterRole restrict-access-role to the newly created ServiceAccount psp-restrict-sa.
正確答案:
See the Explanation below
Explanation:
Explanation:
問題5
SIMULATION
Create a new NetworkPolicy named deny-all in the namespace testing which denies all traffic of type ingress and egress traffic
Create a new NetworkPolicy named deny-all in the namespace testing which denies all traffic of type ingress and egress traffic
正確答案:
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.
---
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.
問題6
SIMULATION
Documentation
Deployment, Pod Security Admission, Pod Security Standards
You must connect to the correct host . Failure to do so may result in a zero score.
[candidate@base] $ ssh cks000036
Context
For compliance, all user namespaces enforce the restricted Pod Security Standard .
Task
The confidential namespace contains a Deployment that is not compliant with the restricted Pod Security Standard . Thus, its Pods can not be scheduled.
Modify the Deployment to be compliant and verify that the Pods are running.
The Deployment's manifest file can be found at /home/candidate/nginx-unprivileged.yaml.
Documentation
Deployment, Pod Security Admission, Pod Security Standards
You must connect to the correct host . Failure to do so may result in a zero score.
[candidate@base] $ ssh cks000036
Context
For compliance, all user namespaces enforce the restricted Pod Security Standard .
Task
The confidential namespace contains a Deployment that is not compliant with the restricted Pod Security Standard . Thus, its Pods can not be scheduled.
Modify the Deployment to be compliant and verify that the Pods are running.
The Deployment's manifest file can be found at /home/candidate/nginx-unprivileged.yaml.
正確答案:
See the Explanation below for complete solution
Explanation:
1) Connect to the correct host
ssh cks000036
sudo -i
export KUBECONFIG=/etc/kubernetes/admin.conf
2) Confirm the failing Pods + see the PSA error (fast)
kubectl -n confidential get deploy
kubectl -n confidential get pods
kubectl -n confidential describe deploy <deployment-name> | sed -n '/Events/,$p' (You'll usually see "violates PodSecurity 'restricted' ..." with the exact missing fields.)
3) Edit the provided manifest
vi /home/candidate/nginx-unprivileged.yaml
You must ensure the Pod template becomes compliant. Add/ensure the following exact blocks:
4) Add Pod-level securityContext (under spec.template.spec)
Find:
spec:
template:
spec:
Add this block under it (or merge if securityContext: already exists):
securityContext:
runAsNonRoot: true
runAsUser: 65535
seccompProfile:
type: RuntimeDefault
5) Add Container-level securityContext (under the nginx container)
Find:
containers:
- name: ...
image: ...
Under that container, add (or adjust) this exact block:
securityContext:
allowPrivilegeEscalation: false
readOnlyRootFilesystem: true
capabilities:
drop:
- ALL
If there are multiple containers, apply the same container securityContext to each one.
Save and exit:
:wq
6) Apply the manifest to the confidential namespace
kubectl -n confidential apply -f /home/candidate/nginx-unprivileged.yaml Wait rollout:
kubectl -n confidential rollout status deployment/<deployment-name>
If you don't know the deployment name from the file, list:
kubectl -n confidential get deploy
7) Verify Pods are running
kubectl -n confidential get pods -o wide
If still failing, show the exact PSA violation (this tells you what else to fix):
kubectl -n confidential describe pod <pod-name> | sed -n '/Events/,$p'
Quick "if it still fails" fixes (common restricted blockers)
Open the manifest again and ensure these are NOT set (or are removed/false):
hostNetwork: true
hostPID: true
hostIPC: true
any hostPort:
privileged: true
capabilities.add:
seccompProfile: Unconfined
runAsUser: 0 or runAsNonRoot: false
Then re-apply.
Minimal compliant result (what the grader expects)
Your Pod template should include:
seccompProfile: RuntimeDefault
runAsNonRoot: true (and a non-root UID like 65535)
container: allowPrivilegeEscalation: false
container: capabilities.drop: [ALL]
container: readOnlyRootFilesystem: true
Explanation:
1) Connect to the correct host
ssh cks000036
sudo -i
export KUBECONFIG=/etc/kubernetes/admin.conf
2) Confirm the failing Pods + see the PSA error (fast)
kubectl -n confidential get deploy
kubectl -n confidential get pods
kubectl -n confidential describe deploy <deployment-name> | sed -n '/Events/,$p' (You'll usually see "violates PodSecurity 'restricted' ..." with the exact missing fields.)
3) Edit the provided manifest
vi /home/candidate/nginx-unprivileged.yaml
You must ensure the Pod template becomes compliant. Add/ensure the following exact blocks:
4) Add Pod-level securityContext (under spec.template.spec)
Find:
spec:
template:
spec:
Add this block under it (or merge if securityContext: already exists):
securityContext:
runAsNonRoot: true
runAsUser: 65535
seccompProfile:
type: RuntimeDefault
5) Add Container-level securityContext (under the nginx container)
Find:
containers:
- name: ...
image: ...
Under that container, add (or adjust) this exact block:
securityContext:
allowPrivilegeEscalation: false
readOnlyRootFilesystem: true
capabilities:
drop:
- ALL
If there are multiple containers, apply the same container securityContext to each one.
Save and exit:
:wq
6) Apply the manifest to the confidential namespace
kubectl -n confidential apply -f /home/candidate/nginx-unprivileged.yaml Wait rollout:
kubectl -n confidential rollout status deployment/<deployment-name>
If you don't know the deployment name from the file, list:
kubectl -n confidential get deploy
7) Verify Pods are running
kubectl -n confidential get pods -o wide
If still failing, show the exact PSA violation (this tells you what else to fix):
kubectl -n confidential describe pod <pod-name> | sed -n '/Events/,$p'
Quick "if it still fails" fixes (common restricted blockers)
Open the manifest again and ensure these are NOT set (or are removed/false):
hostNetwork: true
hostPID: true
hostIPC: true
any hostPort:
privileged: true
capabilities.add:
seccompProfile: Unconfined
runAsUser: 0 or runAsNonRoot: false
Then re-apply.
Minimal compliant result (what the grader expects)
Your Pod template should include:
seccompProfile: RuntimeDefault
runAsNonRoot: true (and a non-root UID like 65535)
container: allowPrivilegeEscalation: false
container: capabilities.drop: [ALL]
container: readOnlyRootFilesystem: true
問題7
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-logs.txt.
2. Log files are retained for 12 days.
3. at maximum, a number of 8 old audit logs files are retained.
4. set the maximum size before getting rotated to 200MB
Edit and extend the basic policy to log:
1. namespaces changes at RequestResponse
2. Log the request body of secrets changes in the namespace kube-system.
3. Log all other resources in core and extensions at the Request level.
4. Log "pods/portforward", "services/proxy" at Metadata level.
5. Omit the Stage RequestReceived All other requests at the Metadata level
Enable audit logs in the cluster, To Do so, enable the log backend, and ensure that
1. logs are stored at /var/log/kubernetes-logs.txt.
2. Log files are retained for 12 days.
3. at maximum, a number of 8 old audit logs files are retained.
4. set the maximum size before getting rotated to 200MB
Edit and extend the basic policy to log:
1. namespaces changes at RequestResponse
2. Log the request body of secrets changes in the namespace kube-system.
3. Log all other resources in core and extensions at the Request level.
4. Log "pods/portforward", "services/proxy" at Metadata level.
5. Omit the Stage RequestReceived All other requests at the Metadata level
正確答案:
Kubernetes auditing provides a security-relevant chronological set of records about a cluster. Kube-apiserver performs auditing. Each request on each stage of its execution generates an event, which is then pre-processed according to a certain policy and written to a backend. The policy determines what's recorded and the backends persist the records.
You might want to configure the audit log as part of compliance with the CIS (Center for Internet Security) Kubernetes Benchmark controls.
The audit log can be enabled by default using the following configuration in cluster.yml:
services:
kube-api:
audit_log:
enabled: true
When the audit log is enabled, you should be able to see the default values at /etc/kubernetes/audit-policy.yaml The log backend writes audit events to a file in JSONlines format. You can configure the log audit backend using the following kube-apiserver flags:
--audit-log-path specifies the log file path that log backend uses to write audit events. Not specifying this flag disables log backend. - means standard out
--audit-log-maxage defined the maximum number of days to retain old audit log files
--audit-log-maxbackup defines the maximum number of audit log files to retain
--audit-log-maxsize defines the maximum size in megabytes of the audit log file before it gets rotated If your cluster's control plane runs the kube-apiserver as a Pod, remember to mount the hostPath to the location of the policy file and log file, so that audit records are persisted. For example:
--audit-policy-file=/etc/kubernetes/audit-policy.yaml \
--audit-log-path=/var/log/audit.log
You might want to configure the audit log as part of compliance with the CIS (Center for Internet Security) Kubernetes Benchmark controls.
The audit log can be enabled by default using the following configuration in cluster.yml:
services:
kube-api:
audit_log:
enabled: true
When the audit log is enabled, you should be able to see the default values at /etc/kubernetes/audit-policy.yaml The log backend writes audit events to a file in JSONlines format. You can configure the log audit backend using the following kube-apiserver flags:
--audit-log-path specifies the log file path that log backend uses to write audit events. Not specifying this flag disables log backend. - means standard out
--audit-log-maxage defined the maximum number of days to retain old audit log files
--audit-log-maxbackup defines the maximum number of audit log files to retain
--audit-log-maxsize defines the maximum size in megabytes of the audit log file before it gets rotated If your cluster's control plane runs the kube-apiserver as a Pod, remember to mount the hostPath to the location of the policy file and log file, so that audit records are persisted. For example:
--audit-policy-file=/etc/kubernetes/audit-policy.yaml \
--audit-log-path=/var/log/audit.log
