Security Identity for N/S Service Traffic

When accessing a Kubernetes service from outside the cluster, the Identity-Based assignment depends on the routing mode.

In the tunneling mode (i.e., --tunnel=vxlan or --tunnel=geneve), the request to the service will have the reserved:world security identity.

In the direct-routing mode (i.e., --tunnel=disabled), the security identity will be set to the reserved:world if the request was sent to the node which runs the selected endpoint by the LB. If not, i.e., the request needs to be forwarded to another node after the service endpoint selection, then it will have the reserved:remote-node.

The latter traffic will match fromEntities: cluster policies.

Differences From Kubernetes Network Policies

When creating Cilium Network Policies it is important to keep in mind that Cilium Network Policies do not perfectly replicate the functionality of Kubernetes Network Policies.

There are two ways Cilium Network Policies do not overlap with existing Kubernetes Network Policy functionality:

  1. Cilium Network Policies that reference the Stream Control Transmission Protocol (SCTP) will not work properly. Currently, Cilium does not support SCTP (see GitHub issue 5719).

  2. Cilium Network Policies that use CIDR blocks to define endpoints controlled by Cilium (i.e. internal to the Kubernetes cluster) will not work properly. As stated under the IP/CIDR based section of this documentation, CIDR policies in Cilium are used to define policies to and from endpoints which are not managed by Cilium (i.e. external to the Kubernetes cluster). This differs from Kubernetes Network Policies which can use CIDR blocks to define policies to and from endpoints which are internal to the Kubernetes cluster (i.e. managed by a CNI other than Cilium).