Subject: Re: weird network outage
To: Steven M. Bellovin <>
From: Hubert Feyrer <>
List: tech-embed
Date: 12/04/2005 07:46:15
On Sun, 4 Dec 2005, Steven M. Bellovin wrote:
> I don't think it was coincidence that rebooting Bigboy made things
> wedge.  I have a plausible explanation for how that reboot could have
> wedged Hellgate, via something that looked like a "break" on a serial
> console.  I have no explanation whatsoever for how that could have
> confused a cable modem.  Any theories?

break on the serial line sounds reasonable, and booting your serial 
console server might result in that. (It always did for sparcs...)
Can you send a manual break from your console server and see if you can 
reproduce the problem? (Not that I would know how to fix your cable modem 
IF that hangs the Soekris...)

One other thing coming to mind is that there's some magic to change the 
magic that the break on the serial line involves to something else.
Looking at options(4), the following may be of interest:

      options DDB_FROMCONSOLE=integer
      options DDB_BREAK_CHAR=integer

Ah, and the one I couldn't remember (and that's of course not referenced 
from abve and not well documented either) is the hw.cnmagic sysctl ...
maybe start with that one.

Greetings from Starbucks @ Astor Place, NYC ;)

  - Hubert