tcpstat reports certain network interface statistics (such as
bandwidth) much like vmstat does for system statistics. It gets its
information by either monitoring a specific interface, or by reading
previously-saved tcpdump data from a file. It has been tested under
Linux, Solaris, FreeBSD, NetBSD, and BSD/OS.

WWW: http://www.frenchfries.net/paul/tcpstat/

- George Reid
greid@ukug.uk.freebsd.org