Submission for mod-protocols-tcp-ip

Eric Gisin (
21 Nov 86 19:59:38 GMT

Path: watmath!egisin
From: egisin@Math.Waterloo.EDU (Eric Gisin @ University of Waterloo)
Newsgroups: mod.protocols.tcp-ip,comp.protocols.tcp-ip,comp.unix.wizards
Subject: Symmetric TCP connection in 4.2 BSD
Message-ID: <3487@watmath.UUCP>
Date: 21 Nov 86 19:59:20 GMT
Sender: Sender: egisin@watmath.UUCP
Lines: 21

I'm trying to develop an IP application under 4.2 BSD
that requires a symmetric TCP connection, as opposed
to the assymmetric connection commonly used in the client/server scheme.
The application is a RSCS line driver.

I was initially going to use UDP in place of BISYNC,
but BISYNC is too brain damaged for this to be done easily.

So I decided to replace the lower half of the RSCS line protocol (VMB)
with TCP. I haven't been able to come up with a way to establish
the TCP connection between two RSCS line daemons symmetrically,
which was trivial to do with UDP (with a socket, bind, and connect).
The TCP specifcation says a TCP should be able to establish
a connection with two active sockets, or that you can passively
wait for a connection from a specified host. 4.2 allows neither of these.

Does anyone have any 4.2/4.3 code to do this?
It would be preferable if it used one well know port
and had the ability to have more than one line daemon per host.
RSCS does not easily allow me to use listen, accept, fork;
the line daemon processes are started at boot time.

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