🚀 go-pugleaf

In article <16608@amdcad.AMD.COM>, bandy@amdcad.AMD.COM (Andy Beals) writes:

> I don't know about you, but the last time I dialed-up a
> computer, I got line-noise.  Interactive smtp is nice but you
> need to have an error-free datastream between them.  So, anyone
> for writing a point-to-point dialup tcp/ip?

     This discussion seems headed to the general possibility of
doing TCP/IP over a dialup phone line, so I'm moving it to
comp.protocols.tcp.  

     Ideally, we'd like to be able to write a daemon that can
listen for non-local IP requests, check against a list of dial-up
machines and their addresses, dial the phone, and then act as a
pass-through.  All this should be done without any kernel
modifications.

     I don't know if this can be done with current 4.x BSD
kernels.  Used to be that all BSD sites had source, but with the
rise of the workstation vendors, that's not true anymore.

     Perhaps raw sockets would provide a means to do this, but
it's been quite a while since I did anything with raw sockets.
Anyone else have any ideas?
-- 
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UUCP:  *!seismo!sundc!hqda-ai!merlin	ARPA:  merlin%hqda-ai.uucp@brl.arpa

> I don't know about you, but the last time I dialed-up a computer,
> I got line-noise.  Interactive smtp is nice but you need to have
> an error-free datastream between them. So, anyone for writing a point-to-point
> dialup tcp/ip?

All fine an well, but how about just wrapping a checksum and sequence
around each line.  E.g.

struct tiny_packet {

		unsigned char checksum;
		unsigned char sequence; /* overkill - % 8 should be fine */
		char line_of_text[];    /* CR/LF terminated */
}

Sure it chokes on 7 bit paths, but you get the idea... It's also
simple enough to be implemented very easily on a micro (a large
win in our case). Use a 7 line window and implied ACKS and away
you go.

|All fine an well, but how about just wrapping a checksum and sequence
|around each line.  E.g.

Better still, why not modify a pair of Kermit programs to invoke
sendmail to deliver mail? If my memory isn't playing tricks on me, the
Kermit protocol allows a mail destination to be specified instead of a
file. I know that printer destinations are supported (but hardly
ever implemented) in the protocol.

	Ken

In article <16608@amdcad.AMD.COM> bandy@amdcad.AMD.COM (Andy Beals) writes:
>Interactive smtp is nice but you need to have an error-free datastream
>between them.  So, anyone for writing a point-to-point dialup tcp/ip?

Isn't that what SLIP (Serial Line IP) is supposed to do? (Maybe not TCP, but
at least IP.) It is my (perhaps mistaken) understanding that SLIP was used
to connect the research machines at Berkeley before Ethernet was available.
I'm not sure if SLIP is still distributed with any Berkeley distributions,
although it is still around (I've seen references to it on the net). It is
still vaguely referred to in the bk(4) man page (at least on SunOS 3.2):

     This line discipline provides  a  replacement  for  the  tty
     driver tty(4) when high speed output to and especially input
     from another machine is to be transmitted over an  asynchro-
     nous  communications  line.  The discipline was designed for
     use by a (now obsolete) store-and-forward local network run-
     ning over serial lines.

My question is:

     With SLIP in place, how difficult would it be to plop TCP and SMTP on
     top of it? Can SLIP be run over dialups or just point-to-point
     connections? (I've always thought it would be nice to run my backups
     using SLIP over a modem line to the network at work when (and if) I get
     a Sun at home. Just dial up, get the server to NFS mount my disk, and
     dump away. :-) ).
-- 
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(518)387-7312|  GE DECnet: advax::"montanaro@desdemona.steinmetz.ge.com"

Earlier I mentioned that SMTP certainly can be implemented over dial-up
connections, and that it can even be done efficiently.  But why bother?
You're still stuck with bouncing your mail from host to host (unless your site
is fortunate enough to be connected to everyone).

kyle jones   <kyle@xanth.cs.odu.edu>
old dominion university, norfolk, va