[SUMMARY] ttya console output to Annex 3 terminal server blocked when DCD is inactive

From: Mark C Olson (mark_olson@adc.com)
Date: Mon Apr 19 1999 - 08:30:04 CDT

My apologies for the delayed summary, I was hoping to get a few more
answers but I will relay the two replies I did receive. Thanks to Ake
Hjalmarsson and Charlie Mengler for their replies.

Ake suggested I look into the Annex terminal server's port
configuration, which did not pan out, sorry.

Charlie pointed out that all messages going to the console could be
redirected to a file or ttyb by modifying /etc/syslog.conf.

For now to avoid the blocked output problem, I am just going remember
to always perform shutdown via a login to ttya. I would rather not
change /dev/console in /etc/syslog.conf because I would still like to
be able to see those msgs on an xterm -C window too.


Mark C Olson
ADC Telecommunications     |telephone: +1 612 936 8008
PO Box 1101, MS 125        |      FAX: +1 612 936 8333
Minneapolis MN 55440-1101  | mailto:mark_olson@adc.com

- Ake Hjalmarsson's response - This might have to do with the settings of the Annex port. Our Annex ports looks like: [port config same as mine snipped]

Good luck!

- Charlie Mengler's response - Here are my two cents worth - There is NO cast in stone requirement that anything be logged (via syslog) to the console. By modifying /etc/syslog.conf all messages currently going to the console could be directed to a file or even ttyb.


Mark C Olson wrote: > > I would like to know how to get around a problem I am having with my > new Sun UE450 server. It is headless, I am using a Xylogics (now Bay > Networks) Annex 3 terminal server with the appropriate OEM cable to > hook up to the Sun's ttya as the console port. I have the Annex's > serial port configured to assert the Data Carrier Detect signal (DCD or > CD, pin 8 on the DB-25 connector) when a telnet connection to it is > active, and to deassert DCD when the telnet connection is broken. This > behavior is necessary so that if the telnet session to the Annex > terminal server is broken, the user currently logged into ttya will be > logged off. > > # eeprom ttya-ignore-cd > ttya-ignore-cd=false > > The problem is, if there is not an active telnet connection to the > Annex 3's serial port, then DCD is inactive, and all system messages > that are sent to the console are blocked. This keeps the system from > being rebooted from a telnet session (not through the Annex terminal > server) unless there is also a telnet session open to the serial port > on the Annex that is hooked to ttya. > > I am concerned about having the ability to do remote admin on this box > in the situation where the Annex is down but the network is still up. > Also, I am not sure, but it seems possible that I may run into other > situations where output to the console being blocked may interfere with > some operations. I know I could set ttya-ignore-cd=true but I would > prefer to avoid the security problem that could cause. > > Being a HW guy I immediately thought of building an device that would > monitor the DCD signal coming from the Annex and briefly drop it to the > UE450 whenever it goes inactive, then re-assert it to the UE450 no matter > what state the DCD signal coming from the Annex is in, basically an > edge-triggered low-going one shot...but I hope there is a way to avoid > using the soldering iron. > > Cheers, > Mark > -- > Mark C Olson > ADC Telecommunications |telephone: +1 612 936 8008 > PO Box 1101, MS 125 | FAX: +1 612 936 8333 > Minneapolis MN 55440-1101 | mailto:mark_olson@adc.com

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