WITS: Auckland X

This is a contiguous packet header trace captured from a passive monitor located within the University of Auckland network. The traces were captured using a single DAG 4.3 card and the WDCap trace capture software. The version of WDCap used was version 3.1.1 and the Libtrace version was 3.0.6.

The passive monitor was located near the edge of the University network and captured all traffic that was coming into existing the University. However, internal traffic that did not pass near the edge would not have been observed at the capture point. The passive monitor performed all of the capture tasks itself, including packet truncation and writing the capture to disk.

Each trace file is named using the following format: yyyymmdd-HHMMSS-[code].gz. The time and date refers to the time in UTC when the first packet in the file was captured. The code refers to the event which caused the previous file to be closed and this new file to be created.

Codes of interest for this traceset are as follows:

• 0 - Rotation boundary was reached

Regular file rotation (code 0) occured daily at Midnight (UTC).

One of the trace files (20091024-000000-0) appeared to have been truncated slightly prematurely, meaning that at least one packet was not correctly written to disk. This means that the trace set is not entirely contiguous and there may be a small number of packets missing between the end of that trace and the start of the next one. We do not know what caused this, but have repaired the trace file to remove the partial packet that was written at the end of the trace file.

Packet records are truncated four bytes after the end of the transport header except in the case of DNS traffic, which is snapped twelve bytes after the end of the transport header. This means that many packets will contain a small amount of user payload - enough to perform some rudimentary layer 7 analysis without seriously threatening the privacy of the network users. ICMP packets which are truncated after any IP and transport headers that may be present in the packet payload.

The IP addresses contained within the packets have not been anonymised. We hope to release an anonymised version of the trace set at some point in the future.

The recommended method for processing these traces is to use Libtrace, which we have developed. There are a number of tools included with libtrace such as a packet dumping utility, a trace format converter (for example, to convert to pcap), a trace splitting/filtering tool and a few statistic generators. We suggest you examine the Libtrace Wiki for more details on the Libtrace tools and the library itself.