A system arranged to monitor a network and to obtain candidate media-streams therefrom and being further arranged to determine whether a candidate media-stream matches a reference media-stream , the system comprising: i) at least one reference fingerprint generator arranged to receive a reference media-stream and generate one or more reference fingerprints, recording a characteristics of the reference media-stream , therefrom; ii) a store of reference fingerprints to which the or each reference fingerprint generated by the fingerprint generator is added across a connection therebetween; iii) at least one monitoring processing mechanism arranged to monitor the network and capture one or more candidate media-streams for processing by the system; and iv) at least one candidate fingerprint generator, arranged to process the or each candidate media-stream captured by the monitoring processing mechanism to generate one or more candidate fingerprints, recording a characteristic of the candidate-media-stream and using the same method to generate the fingerprint as is used to generate the reference fingerprint , therefrom; and wherein the system is arranged such that candidate fingerprints generated by the candidate fingerprint generator are compared against reference fingerprints stored within the fingerprint store to determine whether a reference fingerprint held within the store is substantially the same as the candidate fingerprint in order to identify whether the candidate media-stream that generated the candidate fingerprint is the same, or at least substantially the same, as at least one reference and characterised in that the monitoring processing mechanism comprises first and second processing mechanisms, the first processing mechanism being arranged to start the one or more candidate media streams and act as a media server to re-transmit the candidate media stream to the second processing mechanism and arranging the monitoring processing mechanism to inspect data within the re-transmitted stream to identify the source from which the candidate media-stream originates. i) at least one reference fingerprint generator arranged to receive a reference media-stream and generate one or more reference fingerprints, recording a characteristics of the reference media-stream , therefrom; ii) a store of reference fingerprints to which the or each reference fingerprint generated by the fingerprint generator is added across a connection therebetween; iii) at least one monitoring processing mechanism arranged to monitor the network and capture one or more candidate media-streams for processing by the system; and iv) at least one candidate fingerprint generator, arranged to process the or each candidate media-stream captured by the monitoring processing mechanism to generate one or more candidate fingerprints, recording a characteristic of the candidate-media-stream and using the same method to generate the fingerprint as is used to generate the reference fingerprint , therefrom; and wherein the system is arranged such that candidate fingerprints generated by the candidate fingerprint generator are compared against reference fingerprints stored within the fingerprint store to determine whether a reference fingerprint held within the store is substantially the same as the candidate fingerprint in order to identify whether the candidate media-stream that generated the candidate fingerprint is the same, or at least substantially the same, as at least one reference and characterised in that the monitoring processing mechanism comprises first and second processing mechanisms, the first processing mechanism being arranged to start the one or more candidate media streams and act as a media server to re-transmit the candidate media stream to the second processing mechanism and arranging the monitoring processing mechanism to inspect data within the re-transmitted stream to identify the source from which the candidate media-stream originates. <EOS>