Forensic analysis of network data allows investigators to reconstruct network activity during a particular period of time. These techniques are commonly used to investigate individuals suspected of crimes and to reconstruct the sequence of events that took place during a network-based information security incident.
There are many network forensic analysis tools you can use, several of which may already be present on your network. Here's a rundown of some of the most common network forensic analysis tools:
- Intrusion detection systems (IDS) offer a security-based perspective on network activity. They monitor the network for suspicious traffic and alert administrators when such traffic occurs. The records generated by an IDS play a valuable role when reconstructing a security incident.
- Packet capture tools allow you to record every bit that travels on your network or to limit the data captured so only data that has particular connection characteristics (such as 'to' or 'from' a specific system) is allowed. Due to the large volume of data generated by these tools in a short period of time, it's not feasible to retain packet capture data for an extended length of time.
- A NetFlow data collector records data on each network connection passing through the monitored device(s). This data includes the source, destination and volume of data passed. While it's not possible to preserve packet flows for an extended period of time, NetFlow data may be preserved for a longer period as it only contains summary data about each connection.
These three tools are commonly available on most networks and provide an excellent starting point for a network forensic investigation.
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This was first published in April 2009