A computer system comprising at least one processor, memory including computer program code, the memory and the computer program code configured to, with the at least one processor, cause the system to: - form (110, 540) a split signal of said communication signal at a split point (SPLIT POINT 1, SPLIT POINT 2) in a communication network, said communication signal comprising information, said split signal being identical in information content to said communication signal, - receive said split signal by a network interface controller (NIC1, NIC2, NIC3, NICN) from said split point (SPLIT POINT 1, SPLIT POINT 2); - capture (120, 550) communication packets of said split signal using said network interface controller (NIC1, NIC2, NIC3, NICN) into a transitory memory in a direct memory access operation, said network interface controller operating in real promiscuous mode, - read (130, 560) data of said communication packets from the transitory memory in a direct memory access operation; and - write (130, 560) data of said communication packets to a non-transitory memory in a direct memory access operation so that the data of said communication packets is identical in information content to said communication signal; characterized in that said memory further includes computer program code configured to, with the at least one processor, cause the system to - omit filtering or coalescing said communication packets by said network interface controller (NIC1, NIC2, NIC3, NICN) after capturing said communication packets, - prevent transmitting any network communication towards the network by said network interface controller (NIC1, NIC2, NIC3, NICN), - form a verification code on the basis of said communication packets configured to be used to show that the data of said communication packets in the non-transitory memory has not been tampered with; and - store the verification code to a secure location. - form (110, 540) a split signal of said communication signal at a split point (SPLIT POINT 1, SPLIT POINT 2) in a communication network, said communication signal comprising information, said split signal being identical in information content to said communication signal, - receive said split signal by a network interface controller (NIC1, NIC2, NIC3, NICN) from said split point (SPLIT POINT 1, SPLIT POINT 2); - capture (120, 550) communication packets of said split signal using said network interface controller (NIC1, NIC2, NIC3, NICN) into a transitory memory in a direct memory access operation, said network interface controller operating in real promiscuous mode, - read (130, 560) data of said communication packets from the transitory memory in a direct memory access operation; and - write (130, 560) data of said communication packets to a non-transitory memory in a direct memory access operation so that the data of said communication packets is identical in information content to said communication signal; - omit filtering or coalescing said communication packets by said network interface controller (NIC1, NIC2, NIC3, NICN) after capturing said communication packets, - prevent transmitting any network communication towards the network by said network interface controller (NIC1, NIC2, NIC3, NICN), - form a verification code on the basis of said communication packets configured to be used to show that the data of said communication packets in the non-transitory memory has not been tampered with; and - store the verification code to a secure location.