1. A computer-implemented method for updating network security policy rules when network resources are provisioned in a service landscape instance, the method comprising: categorizing network resources in a service landscape instance based on a service landscape model; responsive to provisioning a network resource, automatically generating one or more security policy rules for the newly-provisioned network resource; and updating security policy rules of pre-existing network resources in the service landscape instance that are determined to be eligible to communicate with the newly-provisioned network resource so as to include the newly-provisioned network resource as a remote resource based on the service landscape model.