[comp.unix.ultrix] SLIP on a DECStation

mazumdar@fredonia.UUCP (Jin Mazumdar) (04/11/90)

	I am faced with the need to add a DECStation 3100 to our
existing systems (4.3BSD) via a serial line.  On a BSD machine one 
has to recompile the kernel with slip option and  run the slattach
program on a tty line not running getty.  After this the line is for
all practical purpose a serial line running tcp/ip protocol.  

	Ultrix seems to have changed the slattach program to include
dial up support, etc. and I do not have source for it.  It is
unsupported by DEC.  I would appreciate hints on how one can hook up a
Ultrix machine to a BSD machine by SLIP.  Please send me E-Mail if you
have done so.

	I have recompiled the Ultrix kernel and found that the slattach
supplied with Ultrix does not work the same way as the BSD version.  I
also was not able to figure out from the documentation in
/etc/sliphosts how I could connect to a non Ultrix host.

	Thanks.


   Jin Mazumdar (uucp:) ...decvax!sunybcs!fredonia!mazumdar          
       (internet:) fredonia!mazumdar@cs.buffalo.edu
			or
	mazumdar%fredonia.fredonia.edu@cs.buffalo.edu
   >>> Dept. Of Math and C. S.                          <<<
   >>> State University of New York College at Fredonia <<<    
   >>> Fredonia, N.Y. 14063         (716) 673 3459      <<<
 

vixie@decwrl.dec.com (Paul A Vixie) (04/14/90)

>>	Ultrix seems to have changed the slattach program to include
>> dial up support, etc. and I do not have source for it.  It is
>> unsupported by DEC.  I would appreciate hints on how one can hook up a
>> Ultrix machine to a BSD machine by SLIP.  Please send me E-Mail if you
>> have done so.

Ultrix and BSD SLIP are protocol-compatible.  This means that if you can
get an Ultrix TTY line into SLIP mode, and the other end is a BSD TTY in
SLIP mode, it will work.

Getting an Ultrix TTY line into SLIP mode is a little bit more complicated
than doing it on BSD.  One thing you can do is get the slattach.c from
UUNET's archives of BSD's networking software.  It should simply compile
and run, at which point you will be dealing at least with an interface
program that you have source for.  Or, if you are willing to read the
/etc/sliphosts file and figure out the "hw" support, you can just use the
(unsupported) /usr/new/slattach that comes with Ultrix.

Compiling if_sl.c from the BSD sources is a little bit tougher, since the
Ultrix-supplied init_main.o does not call slattach().  This is why Ultrix
"slN" devices don't show up in "netstat -i" until they are actually
attached -- slopen() maintains a linked list of interfaces, and until
an interface is opened it doesn't show up on the list.  What this means
is that the BSD version of if_sl.c is useless to you unless you have the
source to the Ultrix version of init_main.c.

Beware that SLIP is unsupported on Ultrix.  If it crashes your machine,
you can't submit bug reports on it.  (Under 3.0, it *will* crash your
machine since there was a bug in the linked list handling in if_sl.c.)
--
Paul Vixie
DEC Western Research Lab	<vixie@decwrl.dec.com>
Palo Alto, California		{ames,att,uunet}!decwrl!vixie

avolio@decuac.dec.com (Frederick M. Avolio) (04/14/90)

In article <VIXIE.90Apr13121237@vixmax.pa.dec.com> vixie@decwrl.dec.com (Paul A Vixie) writes:
>Beware that SLIP is unsupported on Ultrix.  If it crashes your machine,
>you can't submit bug reports on it.  (Under 3.0, it *will* crash your
>machine since there was a bug in the linked list handling in if_sl.c.)

slight clarification.  You can and should submit bug reports on any and all
buggy code you find.  SUpport vs. non-support indicates what you can expect
a patch for, among other things, and the level of effort which might go
into fixing it.  

Now, please -- no flames or sarcastic remarks that I assumre you I can
generate in response to this previous paragraph of mine.  I just wanted
to clarify that, not open speculation about the level of support on Supported
code...

Fred (ducking)