NetworkMiner is a Network Forensic Analysis Tool (NFAT) for Windows. NetworkMiner can be used as a passive network sniffer/packet capturing tool in order to detect operating systems, sessions, hostnames, open ports etc. without putting any traffic on the network. NetworkMiner can also parse PCAP files for off-line analysis and to regenerate/reassemble transmitted files and certificates from PCAP files.NetworkMiner collects data (such as forensic evidence) about hosts on the network rather than to collect data regarding the traffic on the network. The main user interface view is host centric (information grouped per host) rather than packet centric (information showed as a list of packets/frames).

Download
http://sourceforge.net/projects/networkminer/files/networkminer/