Simon Baker writes:

 > Does anyone know of any good protocol loggers that will compile on NetBSD?
 > 
 > Logging src ip / port  to dest ip /port, 
 > An ability to log all ICMP messages would be nice too...

ipfilter comes as part of netbsd, and can do logging as well as
filtering.

tcpdump comes as part of netbsd, and will print more diagnostic-type
information about higher-level protocols also.

 > Logging to syslog / files is also necessary.

ipmon -s will direct the ipfilter logs to syslog, anything can be made 
to send its output to a file.

--
Dan.