azure - How to make a controller method private and accessible only to a specific service in Service Fabric? -

i have 2 services running in service fabric cluster. let's assume service , service b, both of them stateless services. using dns service method communicate between , b , entry point in b api has route. route publicly accessible since have exposed port 80 publicly service. , though trying access api have send appropriate auth tokens, still don't want able outside cluster access api. there other way can achieve trying do? know way use service proxy pattern reason did not work me.