🚀 go-pugleaf

I am finishing an implementation of TCP/IP over Appletalk, the Macintosh
local area network.  The implementation is based on MIT's TCP/IP for the IBM
PC.  One problem remains.  When TELNETing to a 4.1bsd VAX, it is not
possible to initiate a close.  The FIN segment gets sent out, a little extra
data comes in from the VAX (and is ACKED by the Mac), and then nothing until
the VAX resets the connection some seconds later.  The VAX never sends out
its FIN segment.  I have gone over packet logs for hours, vainly looking for
some deviation from the RFC in the behavior of my TCP, but there is none; I
am matching the "Normal Close Sequence" diagram perfectly.  Furthermore,
when I TELNET to a TOPS system, the close sequence works fine.

I tested this with the original MIT IBM PC version of TELNET using a
borrowed PC, with the exact same results.  Eventual reset on the VAX,
immediate close on TOPS.

Yet I have also frequently TELNETed from TOPS-20 to a 4.1bsd VAX, and that
works fine from open to snag-free close.  So I am hesitant to point the
finger at the VAX.  Unfortunately, I have no way of monitoring the Ethernet
to find out what the TOPS and the VAX are saying to each other.

Does anyone know why the MIT PC TCP/IP does not close properly with the VAX
4.1bsd TCP?

(Incidentally, TFTP and TELNET for the Mac over Seagate will be appearing in
net.sources.mac as soon as I get this one last problem squashed or at least
figured out....)
-=-
Tim Maroney, Carnegie-Mellon University, Networking
ARPA:	Tim.Maroney@CMU-CS-K	uucp:	seismo!cmu-cs-k!tim
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