A method is provided to monitor network traffic, including reserving a portion of a system memory for short-term storage of copied network traffic, wherein the system memory is volatile, receiving copied packets of intercepted network traffic traversing a network, wherein the packets are associated with a plurality of respective traffic streams included in the network traffic, storing the copied packets in the portion of the system memory, maintaining an ordered list per traffic stream of copied packets that are stored, removing copied packets selected, based on their positions in their respective ordered lists, from the portion of the system memory based on a storage constraint, receiving an attack alert identifying a packet that is involved in a network attack, identifying the traffic stream that includes the packet identified, and transferring stored copied packets that are included in the identified traffic stream from the portion of the system memory to a long-term storage device.