netdumpd is a simple daemon which basically acts like a daemonized version of tcpdump. It sniffs network traffic on a particular interface and writes the packets it sees to a standard libpcap dump file.
netdumpd was written to log packet headers for statistical analysis by other programs which read pcap dump files such as bpfcount.
The main difference between netdumpd and any number of other programs which can dump network traffic (aside from the fact that it runs as a daemon) is that netdumpd is designed to handle log rotation correctly. When it receives a SIGHUP it will gracefully close and re-open the dump file it is currently writing to, which allows for the dump file to be rotated cleanly and without losing any packets.
If you come across a bug not listed in the README file or if you have any comments or questions feel free to email me (Steve Benson). Don't forget to remove the NOSPAMs from the email address there.