[clue-tech] linux ethernet tty-console?

[Ken MacFerrin]

Jim Ockers wrote:
> Hi CLUEbies,
> 
> Does anyone know of a way to get the Linux kernel to provide a
> console tty-style device over ethernet?  Sort of like telnet or 
> ssh daemon but built into the kernel.
> 
> Yes I know there are security issues.  We're talking LAN only.
> I've seen stuff like this  http://www.selenic.com/netpoll/netconsole.patch
> which lets you see kernel printk() messages on another system via
> ethernet using a utility like netcat or tcpdump or something.
> 
> We have a curses application which is the very first thing init
> runs during boot-up.  Unfortunately if there is something wrong
> with the system the curses application requires user interactive
> input (type stuff in dialog boxes, move the cursor between boxes 
> using the arrow keys, etc.).
> 
> Unfortunately this is on a headless server.  Yes we have a
> serial console.  Unfortunately these systems are deployed in remote
> locations and the serial console cable keeps getting mis-placed
> and delivery of a new one is not possible (plus they are $70 a
> whack, for the industrial strength explosion proof cable).
> 
> The ethernet cable is always connected and we're wondering if
> there is some way to get a tty console right from the kernel via
> ethernet so we can access the curses application over the
> network instead of just via the serial cable which we usually
> don't have.

I used to do something similar with my transparent pf firewall box so I
could still access it from my LAN even though it didn't have an IP
address.  In this case I hooked a null modem serial cable from the
firewall box to my home server and would then ssh into my home server
and use minicom to access the firewall console across the serial connection.

There's a good article about a similar setup using minicom and conserver
here:
http://www.linux.com/article.pl?sid=06/08/29/1316246

-Ken