freebsd-ports/net/nettest/pkg-descr

The nettest and nettestd commands invoke client and server
programs that are used for timing data throughput of vari-
ous  methods  of  interprocess communication.  For TCP and
OSI connections, the nettest program establishes a connec-
tion  with  the  nettestd  program, and then it does count
writes of size bytes, followed  by  count  reads  of  size
bytes.  For UDP, the nettest program performs only writes;
reads are not performed.  The nettestd  program,  if  used
with  UDP connections, reads the data packets and prints a
message for each data packet it receives.  The number  and
size  of  the  reads and writes may not correlate with the
number and size of the actual data packets that are trans-
ferred; it depends on the protocol that is chosen.  If you
append an optional k (or K) to the size, count, or bufsize
value, the number specified is multiplied by 1024.