File Transfer by Null Modem Cord HOWTO

File Transfer by Null Modem Cord HOWTO

Post by Bloody Viki » Sat, 14 Apr 2001 10:53:17



For those looking for cheap easy connectivity between your Linux laptop and a
non-Linux desktop, a null modem cable is hard to beat.

First step: Make sure your non-Linux computer has a terminal programme that
can transfer files and a serial port.

Second step: Make sure the Linux box has mgetty installed and a free serial
port.

Third step: Buy the null modem cord and attach to both computers in the
obvious way.

Fourth step: Fire up the two boxes, and on the Linux box, login as root with
any old virtual terminal and type in "mgetty -s 115200 -r /dev/ttyS0" (for COM1
/dev/ttyS1 for COM2, etc.) On the other box, fire up a terminal programme and
use it to connect and login. I use VT100 emulation for this.

Fifth step: Enjoy!

If you have a laptop and havn't found out which networking cards to use with
it, this method can be used in a pinch for cheap file transfer. It'll be slow
for big tarballs, however.

With one of them BBS type serial port cards with the octapus cords, you can
have a terminal server desktop serving a bunch of laptops in an office. Even
better is to set up PPP with Slurp for Windows clients.

CAUTION: While the command line mgetty bit works, it works for _one_ login per
running of the command. That means you need some mechanism of looping it so
when a logout occurs, it's rerun automagically for the next person to login
with. You get to make a daemon.

Many people accomplish the above with agetty but that has the problem of
auto-respawning causing stderr messages showing up on the console. Since I
don't know how to stop the respawning, I prefer the mgetty method. The man
page for mgetty is straightforward for command line arguments to run it to
transfer files.

Besides laptop file transfers, it can be used to transfer files between all
the other OSes, so long as they have a term proggie and support a null modem
cord. Config Slurp, and you have the null modem PPP.

--
FOOD FOR THOUGHT: 100 calories are used up in the course of a mile run.
The USDA guidelines for dietary fibre is equal to one ounce of sawdust.
The liver makes the vast majority of the cholesterol in your *stream.

 
 
 

File Transfer by Null Modem Cord HOWTO

Post by Edward Roste » Thu, 19 Apr 2001 05:33:58


Quote:> If you have a laptop and havn't found out which networking cards to use
> with  it, this method can be used in a pinch for cheap file transfer.
> It'll be slow  for big tarballs, however.

Try a parallel port (but it might be more work), coz its much faster.

Quote:> CAUTION: While the command line mgetty bit works, it works for _one_
> login per  running of the command. That means you need some mechanism of
> looping it so  when a logout occurs, it's rerun automagically for the
> next person to login  with. You get to make a daemon.

> Many people accomplish the above with agetty but that has the problem of
>  auto-respawning causing stderr messages showing up on the console.
> Since I
>  don't know how to stop the respawning, I prefer the mgetty method. The
> man  page for mgetty is straightforward for command line arguments to
> run it to  transfer files.

Couldn't you use a line in /etc/inittab to get it to respawn?

-Ed

 
 
 

File Transfer by Null Modem Cord HOWTO

Post by Bloody Viki » Sat, 05 May 2001 11:00:58


: Couldn't you use a line in /etc/inittab to get it to respawn?

I tried that, and it respawned way too fast, causing stderr messages on the
console. That's why I chose the method I chose.

--
FOOD FOR THOUGHT: 100 calories are used up in the course of a mile run.
The USDA guidelines for dietary fibre is equal to one ounce of sawdust.
The liver makes the vast majority of the cholesterol in your *stream.

 
 
 

1. need help with null-modem file transfers

I am looking for assistance with transferring files between a Sparc-2
(SunOS 4.x) and an Ultra1-140 (SunOS 5.x).  I have tried tip, but cannot
seem to get a login process on either system to see the tty.  I am
running a Digitizer on ttyb (i think ) on the Sparc-2, but ttya is
free.  The Ultra has no serial devices attached.

I would connect them on a network, but am not allowed to do so, for
"administrative" reasons.

Any help with "tip" or a suggestion for other software would be greatly
appreciated.
            -Rick

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