network type console and /etc/ttys

[Matthew Seaman]

On Mon, Mar 08, 2004 at 01:07:09PM -0800, Gary W. Swearingen wrote:
> /etc/ttys has a field called "type" and says that "network" is an
> option, but I can't find that expanded upon in its manpage or in the
> Handbook or FAQ.  I've tried googling, but my searches either return a
> small list with no relevant info or a huge list that seems to be all
> off topic.
> 
> The file has "network" for "Pseudo terminals" (ttyp#), but that isn't
> enough of a clue for me, either.

The pseudo-terminal entries are used in a) xterm windows and b) when
you telnet or ssh into the system remotely.  It's basically a software
construct that behaves like a real physical terminal.  However, it's
not sufficiently like an actual terminal that you can use it instead
of one.
 
> The basic question is whether and how one can set up a remote (LAN)
> terminal, probably using that "network" type in /etc/ttys (without
> using X11).  How does one specify which network port, for example?
> It seems like it should be handled very much like setting up a
> RS-232-type serial terminal.

Just ssh into the box over the network -- the 'tty' command will tell
you your terminal is '/dev/ttyp1' - that 'p' in the name (or 'q' or
'r' or 's' or 'P' or 'Q' or 'R' or 'S') indicates a
pseudo-terminal. (real terminals are called something like
/dev/console, /dev/tty, /dev/ttyv1 (for the console virtual terminals)
or /dev/ttyd1 (for RS-232-type serial terminals))
 
> The original problem was whether and how one can do that for the
> console terminal, to support even single-user mode.
> 
> Seems like basic stuff, but I've never seen mention of it before.

Actually this comes up on this list quite regularly.  Search for
'remote console access' in the list archives.  The trick, basically,
is to tell the system to use Serial A as it's console -- how to do
that is described in the Handbook:

    http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/install-advanced.html
    http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/serialconsole-setup.html

Now, setting up a remotely accessible console can be as simple as
stringing a null-modem cable between the serial port on that machine
and another one that happens to be near by, and using tip(1) as a
terminal emulator on the other machine.  Or it can be solved by
throwing money and hardware at the problem -- for instance Lightwave
(now part of Lantronix) make a nice range of console server equipment.

One particularly amusing solution is RealWeasel -- mostly because of
the cartoon on the front page of their web site:

    http://www.realweasel.com/

There's also this article on the FreeBSD site about using console servers:

    http://www.freebsd.org/doc/en_US.ISO8859-1/articles/console-server/index.html

	Cheers,

	Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.                       26 The Paddocks
                                                      Savill Way
PGP: http://www.infracaninophile.co.uk/pgpkey         Marlow
Tel: +44 1628 476614                                  Bucks., SL7 1TH UK
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