FreeBSD 6.1 Tor issues (Once More, with Feeling)

[Robert Watson]

On Sun, 2 Jul 2006, Fabian Keil wrote:

> Robert Watson <rwatson at FreeBSD.org> wrote:
>
>> On Sun, 2 Jul 2006, Fabian Keil wrote:
>
>>> After manually triggering a test panic through debug.kdb.enter I
>>> could enter ddb and everything seemed to be working.
>>>
>>> However today I got another hang and couldn't enter the debugger by
>>> sending BREAK. It is the same BREAK ssh sends with ~B, right?
>>>
>>> Even after rebooting, sending break didn't trigger a panic, so
>>> either I'm sending the wrong BREAK, or my console settings are
>>> still messed up. Any ideas?
>>
>> What serial software are you using to reach the console?
>
> I use ssh to log in to a console server, hit enter and am connected to the 
> console. I have no idea what kind of software is used between console server 
> and console.

You probably need to find out in order to find out what break sequence to 
send.  Alternatively, you can use ALT_BREAK_TO_DEBUGGER, which defines an 
alternative break sequence without relying on a serial break (which is an 
out-of-band break signal).

>> The delivery mechanism for the break will depend on the software you're 
>> using...
>
> The ssh man page offers:
>
> |~B      Send a BREAK to the remote system (only useful for SSH protocol
> |        version 2 and if the peer supports it).
>
> I am using ssh 2, but the only reaction I get is a new line.
>
> |FreeBSD/i386 (tor.fabiankeil.de) (ttyd0)
> |
> |login: ~B
> |

It sounds like your serial console server may not know how to map SSH break 
signals into remote serial break signals.  Try ALT_BREAK_TO_DEBUGGER.  Here's 
the description from NOTES:

# Solaris implements a new BREAK which is initiated by a character
# sequence CR ~ ^b which is similar to a familiar pattern used on
# Sun servers by the Remote Console.
options         ALT_BREAK_TO_DEBUGGER

Robert N M Watson
Computer Laboratory
University of Cambridge