The opposite of server-side transparency (see "transparent"). A transparent connexion (TCP) or data stream (UDP) in which the firewall is transparent to the server. In other words, the client's IP address, and not the firewall's IP address, is the source of the traffic on the server's side of the firewall. Typically used for inbound access, so that the server on the protected network can log the client's IP address or FQN.