network type console and /etc/ttys

[Matthew Seaman]

On Tue, Mar 09, 2004 at 11:27:35AM -0800, Gary W. Swearingen wrote:
> Matthew Seaman <m.seaman at infracaninophile.co.uk> writes:
> 
> > On Mon, Mar 08, 2004 at 01:07:09PM -0800, Gary W. Swearingen wrote:
> 
> >> 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:
> 
> Thanks, but as you noted, it's not hard to find info about remote
> serial port consoles.  My question was about doing a similar thing
> over Ethernet.  That is, with a single Ethernet cable between the
> local NIC and the remote NIC, not necessarily on a real, many-port
> network, and definitely without telnet, ssh, and other network
> services running -- so that it works from single-user mode, working
> just like a serial console.  I'm sure the Ethernet support is mostly
> there in the kernel, but maybe something fairly simple is missing from
> whatever reads /etc/ttys; eg, to know which NIC is to be the console
> port), and maybe there needs to be an ethernet-getty (similar to
> telnet, but which needn't even use IP addresses).  And maybe a
> "ethconsole" addition to "comconsole" and "vidconsole" in
> "/boot/loader.conf".

Well, yes.  Most console servers do that by providing ethernet access
nowadays.

The ethernet-getty you describe can't work: there's nothing special
about getty per-se, that's just a process that handles activity on
some terminal.  It doesn't even come into single user mode or the
early stages of the boot process.

The network functionality you want is provided precisely by telnetd(8)
or rshd(8) or more usually sshd(8).  However, you can't use those for
the console, because the console has to operate independantly of the
state of the OS.  It's pretty pointless having a remote console if you
can't type 'boot' into it.  And it's hard to have the network
interface configured and up, with network comms programs running when
the system is sitting at the boot-loader prompt.
 
> Maybe I'm missing something, but it seems like this would be a often-
> used feature, especially as RS-232 serial ports will probably be
> disappearing from new motherboards in the next few years.

Maybe the RS-232 serial ports will disappear, but the USB serial ports
will still exist.  This sort of functionality is far too important for
a serious mother board manufacturer to ever consider leaving out of a
server class system.  Maybe it will be a different to what we use
today, but something with similar capabilities will exist.

	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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