A system is provided comprising one or more application layer audit proxies arranged to obtain application layer network traffic sent in a network. Each of the application layer audit proxies configured to: receive application layer network traffic sent as part of a communication session between a producer entity and a consumer entity; record information about the application layer network traffic to an audit log in a distributed permissioned database comprising a blockchain of immutable data blocks; and forward the application layer network traffic to the producer entity or to the consumer entity.