Abstract: An apparatus and method allow for distribution of a streamed signal within a group of users in a computer network, the users accessing client terminals (10, 20, 30, 40) for participation in a multicast session. The apparatus includes connecting links (12, 22, 32, 42) adapted to connect the client terminals of users and related equipment, such as capturing elements (16, 26 . . . ; 18, 28 . . . ), to the multicast session, preferably via the Internet or other interconnecting network. An extension header is added to data packets of the streamed signal, the extension header including identification data relating to the intended recipient of a packet. A filtering element (14, 24, 34, 44) is associated with the receiving client and is adapted to filter out data packets having the address of the recipient and receiving the streamed signal. Consequently, the existing communication channel can be reused.

Abstract: A method and system for transmitting a media stream of data from a sending client terminal to a receiving client terminal, the terminals being arranged in a protected computer environment including at least one protective unit in association with a data forwarding element. The protective unit is intended to protect the receiving client terminal from data transmitted from unauthorized sending clients. The method includes: transmitting authorization data from the receiving client terminal to sending client terminal via the protective unit for instructing the unit to allow return of a media stream from the sending client terminal to the receiving client terminal during a predetermined period of time. Moreover, the method includes the step of: the receiving client terminal is adapted to independently transmit authorisation data via the protective unit at shorter intervals than the predetermined period of time for maintaining the allow return mode of the protective unit.