Principles

A packet is emitted by the client. A user Id is associated to this packet and the autorisation is given on a user and filtering base.

1 A standard application sends a packet.
2 The Nufw server queues the packet and sends an auth request packet to the Nuauth server.
3 The Nuauth server sends to all nufw agents running on the client computer an authentication request
4 The Nufw client run by the user whose application sent traffic sees that a connection is being initiated and sends a user request packet.
The Nuauth server sums the auth request and the user request packet and checks this against an authentication authority.
5 The Nuauth server replies to the Nufw server accordingly
6 The Nufw server transmits the packet following the answer given to its request.

All green flows on the "global process" figure should take place in a protected environnement.

The orange flow is dangerous because it is an unprivilegied zone access to a protected zone. So, particular care is needed to securise this access.