19 Mar
2017
19 Mar
'17
11:57 a.m.
Hi all, over on the uucp project we are struggling with a problem. If a
user is logged in with telnet, and they disconnect the telnet session,
their shell hangs around. The next person that telnets in gets the shell.
SimH, with the -a -m flags on a simulated DZ line, has these modem flags:
Telnet connected: Modem Bits: DTR RTS DCD CTS DSR
Telnet disconnected: Modem Bits: DTR RTS DSR
So, DCD and CTS are being dropped, but getty (or something) isn't responding
and (presumably) sending a HUP signal to the shell.
Is there anybody with some modem or getty knowledge that can help?
Thanks, Warren
19 Mar
19 Mar
12:18 p.m.
This sounds like a setsid() like problem. As in the server is not
cleaning up. BSD didn't have setsid, I think that was a POSIX thing
and it was one of the good things that POSIX added. That's my
memory, someone will correct it.
On Sun, Mar 19, 2017 at 03:57:36PM +1000, Warren Toomey wrote:
Hi all, over on the uucp project we are struggling
with a problem. If a
user is logged in with telnet, and they disconnect the telnet session,
their shell hangs around. The next person that telnets in gets the shell.
SimH, with the -a -m flags on a simulated DZ line, has these modem flags:
Telnet connected: Modem Bits: DTR RTS DCD CTS DSR
Telnet disconnected: Modem Bits: DTR RTS DSR
So, DCD and CTS are being dropped, but getty (or something) isn't responding
and (presumably) sending a HUP signal to the shell.
Is there anybody with some modem or getty knowledge that can help?
Thanks, Warren
--
---
Larry McVoy lm at mcvoy.com http://www.mcvoy.com/lm
2:06 p.m.
On Sun, Mar 19, 2017 at 03:57:36PM +1000, Warren Toomey wrote:
Hi all, over on the uucp project we are struggling
with a problem. If a
user is logged in with telnet, and they disconnect the telnet session,
their shell hangs around. The next person that telnets in gets the shell.
Some more data points. Vanilla 32V and 3BSD do HUP the shell when the DCD
drops on a SimH telnet disconnect. Vanilla 4.2BSD and 4.3BSD don't!
Very curious.
Warren
4:08 p.m.
On Sun, Mar 19, 2017 at 06:06:40PM +1000, Warren Toomey wrote:
Some more data points. Vanilla 32V and 3BSD do HUP the
shell when the DCD
drops on a SimH telnet disconnect. Vanilla 4.2BSD and 4.3BSD don't!
Found it. In /sys/conf/GENERIC, the dz lines have flags turned on to
ignore DCD:
device dz0 at uba? csr 0160100 flags 0xff vector dzrint dzxint
I just turned off the flags and now a Telnet disconnect causes the
shell to be HUP'd and killed. Phew!
Warren
2620
days inactive
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days old
4 comments
3 participants
participants (3)
-
Jacob Goense -
Larry McVoy -
Warren Toomey