PeekPup is a small subsystem enabling one to peek at Pups going  to and
from a particular Ethernet host.  It is intended as an aid in debugging
new Pup software.

PeekPup is invoked by the command

    PeekPup hostnumber filename

where "hostnumber" is  the Ethernet address  (octal) of the  host whose
packets you  want to spy  on and "filename"  is the name  of a  file to
write the output on.  The program then looks for packets whose Ethernet
source or  destination address  is equal  to "hostnumber",  and buffers
them in  memory.  For each  Pup so processed,  "!" is displayed  on the
screen.  PeekPup terminates when any key is pressed, at which  point it
interprets the  last 200  Pups received  and writes  the result  on the
specified file.

The output is mostly self-explanatory.  The numbers in the  left margin
represent a  millisecond clock (with  no particular starting  value and
wrapping around  at 32768).  For  each Pup, a  few lines of  output are
generated; the information about Pups sent to the host being spied upon
is indented further than information about Pups generated by that host.
Pup headers are  fully interpreted, and  Pup contents are  displayed as
either text or a series of octal numbers representing bytes; large Pups
get only the initial  portion of their contents displayed,  followed by

                   Copyright Xerox Corporation 1979