oc adm diagnostics NetworkCheck fail due to DNet2006

Issue

• When I run oc adm diagnostics, I got following error:

# oc adm diagnostics
  ... ship ...
ERROR: [DNet2006 from diagnostic NetworkCheck@openshift/origin/pkg/diagnostics/network/run_pod.go:142]       Creating network diagnostic pod "network-diag-pod-c8bmn" on node "os01aprt001" with command "openshift infra network-diagnostic-pod -l 1" failed: pods "network-diag-pod-c8bmn" is forbidden: unable to validate against any security context constraint: [provider restricted: .spec.securityContext.hostNetwork: Invalid value: true: Host network is not allowed to be used provider restricted: .spec.securityContext.hostPID: Invalid value: true: Host PID is not allowed to be used provider restricted: .spec.securityContext.hostIPC: Invalid value: true: Host IPC is not allowed to be used spec.volumes[0]: Invalid value: "hostPath": hostPath volumes are not allowed to be used provider restricted: .spec.containers[0].securityContext.privileged: Invalid value: true: Privileged containers are not allowed provider restricted: .spec.containers[0].securityContext.hostNetwork: Invalid value: true: Host network is not allowed to be used provider restricted: .spec.containers[0].securityContext.hostPID: Invalid value: true: Host PID is not allowed to be used provider restricted: .spec.containers[0].securityContext.hostIPC: Invalid value: true: Host IPC is not allowed to be used]

• Why this error happens?