Re: How to "bridge" a serial connection over the Internet?

  Hi Saku, all,

  I'm pretty good with the "console server" (reserve-telnet) concept, and I've worked with many serial concentrator devices, including the Cisco lines. But this questions is different than most "typical" deployments in two ways;

  -  low port density at the remote sites (Only one, or maybe two, serial ports at each location)

  -  the 'destination' for the auto-telnet is not a serial concentrator, but a socket on the linux (or Windows) host itself, which an application will see as a TTY or COM port.

  The reasons for looking into this applications are the costs.  At a few hundred dollars each, I can't put many 2-port concentrators around. If I put another serial concentrator at the server end to essentially "present the serial ports locally", I'd still need another concentrator, connected with null modem to let the OS connect to them and interact (again, with some substantial cost).

  It's not a typical conserver-type model. But, I offered the puzzle hear, because many of us are known for thinking beyond the traditional implementations, and for bringing unique solutions and suggestions to the conversations. (Thank Rob. :-)

  Right now, the solution is to run with a dedicated server at each remote site, running an application which watches the serial port(s), and then the server feeds a TCP stream to an aggregation server across the Internet. If I leave out the server, the cost of a small console server would cost just about the same, and I still need to resolve the server-end connection.

  This could be an Arduino with an Ethernet shield, or a small 'embedded' serial-to-Ethernet device, but it needs to work in the "telnet" direction, as opposed to the "reverse-telnet" direction. And, I'd prefer something a bit mature, rather than a hack.(If I roll the code wrong, it will mean a visit to many remote sites to install a new code version.) Time to explore the Digi website, I think!

     Best regards,

              -Z-      http://www.conserver.com/consoles/Cisco/ciscocons.html

On Mon, Apr 29, 2013 at 10:49 PM, Saku Ytti <saku@ytti.fi> wrote:

On 30 April 2013 00:52, Zonker <consoleteam@gmail.com> wrote:

> local modem          console server?  (auto-telnet to IPaddr:port)
>        `------RS-232 cable------'
>
>   At the IP address (the server), preferably a Linux machine, the TCP
> listener would present as a local TTY. No exec/login function. A local
> application would use the TTY port as though it was a locally-attached
> serial port or USB serial dongle.

Pretty much any Cisco CPE can do this, it's called 'reverse-telnet'.
You attach your RS232 device to Cisco and then telnet to like 2001
port on Cisco to get to the serial port.

There are obviously solution for how to do this on Linux as well.
'opengear' is common vendor, which is just embedded linux doing this,
they offer their software open-source.

I'm sure there are more than one apt-gettable packages to solve this as well.

If you need to RS232 port to appear on local machines as serial port
(maybe proprietary management software, not just telnet) then you need
RFC2217 solution, which also you can acquire open source to your linux
PC.



--
  ++ytti

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