Serial Console Question (re-sent w/ subject)

[David Kelly]

On Tuesday 22 April 2003 09:45 am, Daryl Chance wrote:
>
> I've searched the handbook and haven't found anything
> about this.  I'm trying to setup a serial console for
> some remote machines i'm admining.  I want to set it
> up using null modem cables, as it says in the handbook
> like so:
> www:s1 - sql:s2
> www:s2 - mail:s1
> sql:s1 - mail:s2
>
> From what i've read it needs a dumb terminal?  Is it
> possible to do it without using this and only setting
> it up with the null modem cables and nothing else?  I
> assume this is possible, but the documentation doesn't
> seem to say anything about using only the cables and
> nothing more.

Partly, the handbook shouldn't say anything about the cables when 
discussing serial consoles because that is another issue.

These days the most common serial port is the DB9P mutation which 
appeared on the IBM PC-AT. You will need a "null modem" cable with 
female connectors, ie: DB9S (S = socket, P = pin). 

If I understand your table correctly you have 3 hosts, www, mail, and 
sql, and you wish to cross-connect their two each serial ports so that 
each may serve as the "dumb terminal" console of another.

So for starters, by default, the zero'th serial port on a FreeBSD system 
is flagged in the kernel configuration for use as a serial console. 
Extracted from /usr/src/sys/i386/conf/GENERIC, the flag bit in 0x10 is 
the critical point:

# Serial (COM) ports
device          sio0    at isa? port IO_COM1 flags 0x10 irq 4
device          sio1    at isa? port IO_COM2 irq 3
device          sio2    at isa? disable port IO_COM3 irq 5
device          sio3    at isa? disable port IO_COM4 irq 9

So anyway, you need to remember its only the sio0 port where console 
messages appear.

Of all the "terminal" software packages available, I still prefer good 
old simple ancient kermit. /usr/ports/comms/kermit/

On a FreeBSD host I use to connect to the serial console of another I 
have this in my ~/.kermrc. If the other system isn't powered up yet, or 
its serial port is not awake the CARRIER-WATCH parameter below prevents 
kermit from closing the connection. Notice also that you might put a 
getty on /dev/ttyd0 in /etc/ttys but when you connect out with kermit 
(or what ever you chose) you use /dev/cuaa0.

set CARRIER-WATCH off
set line /dev/cuaa0
set speed 9600

-- 
David Kelly N4HHE, dkelly at hiwaay.net
=====================================================================
The human mind ordinarily operates at only ten percent of its
capacity -- the rest is overhead for the operating system.