Michael Robinson <[EMAIL PROTECTED]> wrote in list.freebsd-stable:
 > Last night, I was running a very large Postgresql query on one of my 
 > colocated development servers when all of a sudden the session completely
 > froze.  Since then, I can get TCP connections to all the open ports, but
 > they just hang with no services ever coming up.  Ping works fine.

I have once written a small kernel hack which I called "ICMP
REBOOT".  When you send a certain ICMP packet from a certain
host or network, the machine logs the host and panics.  The
packet can be sent with a modified ping command.

It is very useful, because the reception of ICMP packets is
performed by the kernel on the lowest level in the interrupt
handler, which means that there's a good chance that it will
still work, even if the system is pretty much dead.  This hack
saved my life a few times.  ;)

I considered submitting the patch, but I guess it wouldn't be
committed because it's a "dirty hack".  Someone else who has
access to your network could easily reboot your box using IP-
spoofing, because it's authenticated by IP addresses only.
It's probably a good idea to use it behind a firewall that
drops unknown ICMP packets.

If someone is interested, I've put the hack online here:
http://www.fromme.com/icmpreboot.tar.gz
Please read the README file.  Use at your own risk.

Regards
   Oliver

-- 
Oliver Fromme, Leibnizstr. 18/61, 38678 Clausthal, Germany
(Info: finger userinfo:[EMAIL PROTECTED])

"In jedem St�ck Kohle wartet ein Diamant auf seine Geburt"
                                         (Terry Pratchett)


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