The "nit_if.o-sunos4.0.3" is a bugfixed version of the "/sys/sun2/OBJ/nit_if.o"
kernel module. With this patch you will be able to use the /dev/nit interface
correctly. (Like for example with the "nnstat" package). 
 
PLEASE NOTE: This is *NOT* a patch coming from Sun but is one I and a friend
of mine (Lars Willfor <willfor@lysator.liu.se> hacked together by looking at
the disassembled source (gdb and adb are wonderful things! :-) of the Sun3
patched "nit_if.o" that is available from other places and comparing that
against the original Sun2 object file. We then inserted two "nop" instructions
at the place where it differed and now it seems to work. So use at your own
risk and don't blame Sun if something goes wrong.
 
/Peter Eriksson <pen@lysator.liu.se>