killing zombies

[Barry Shein]

>From: harris at imsvax.UUCP (Harris Reavin)
>Subject: Re: killing zombies
>
>     Unfortunately no unix wizard on the net had a solution for zombie
>processes that disable ports and refuse to die from a "kill -9". I got
>mail from a number of other system administrators who had the same problem
>and asked for the solution if I found one short of rebooting. We discovered
>locally a way to drive a stake through a zombie's heart that I did not
>mention in the previous article. It is better than a reboot but is still a
>lot of trouble. We disconnect the cable from the controller of the affected
>port, change the ttys entry to turn off the port, reconnect the cable,
>and reedit the ttys file to turn the port on again. This usually works.
>I still hope that someone may come up with a better solution that does
>not involve crawling around the back of the computer in search of the
>proper cable.

Ah, and thus you reveal your 'real' problem: Improperly hooked up
cables (wizards *never* do that :-).

See, my suspicion is that when you gave up the ability to 'hang-up' the
line by running 3-wire circuits you opened the possibility (really,
closed a possible solution to) this and other problems (like getting
your terminal all hung up in RAW mode or some such.) If this isn't the
case then how come unplugging works? It only drops a line.

Yes, you're right, kill oughta work and its a bug but for security's
sake consider going to 'modem' controlled wires where possible (most
terminals support this, asserting some sort of DTR which may need to be
jumpered to other pins but at any rate assure a hang-up if the terminal
is powered off [yet another security bug with three-wire circuits,
turning off a terminal *should* log you off.])

But, don't give up hope, I believe there is still a bug in some drivers
that may leave zombies even if you hang-up!

	-Barry Shein, Boston University