[Gllug] Changing machine's IP address

[John Hearns]

On Fri, 2001-11-02 at 12:17, Paul Brazier wrote:
> > >(It would be embarrassing to get home only to find we couldn't access
> > >the server remotely - do these places have terminals that 
> > you can use to
> > >double check your setup is OK while you're there?)
> > 
> > In theory, our hosting centre (Colt) are meant to have a screen and
> > keyboard in each server room, but in reality, you're better of taking
> > a laptop along with you. Just plug it into the serial port of your
> > box (you *have* got it set up to support a serial console, haven't
> > you?)
> 
> Not sure what this means exactly, 


Paul, the answer to this should be generally useful.

It is extremely, extremely useful to have a 'Serial Console' enabled
on any server machine. 
Non-PC class machines, like SGIs etc, and any 'big iron' have this
as standard - ie. you can use a serial terminal, normally VT-100
compatible, to log into and control the machine.
Nowadays, mostly people use a laptop or PC with a serial cable
and a terminal emulator, like minicom.


Actually, most PC-class machines lack true serial console functionality,
such that you cannot get down to the BIOS level, for instance.
This is changing though, and some motherboards offer it.


To set the serial console up, look at the HOWTO:
http://www.linuxdoc.org/HOWTO/Remote-Serial-Console-HOWTO/


The serial terminal has advantages:

it can save your hide in an emergency when all you need do is bring
a laptop up to it, or maybe a PDA with a serial cable

you can have a multi-way serial terminal server, like a PC with
a Cyclades card in it. Run serial lines to all servers in the machine
room, and you can ssh/telnet to the PC then get terminal control
sessions on all your servers

you could hang a modem off the serial console, should you need to do
remote support. But watch for the security implications of this -
I don't consider this to be really safe.


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