Mailing List Archive

How to "bridge" a serial connection over the Internet?
This is a bit of an unusual connection style. Any ideas how to achieve
it? I think I'm suffering tunnel vision, and I could use a few clues to
help expand my vision.

At the remote site is a modem-like device. The remote site uses DHCP
addressing, and NAT to get to the Internet, so I'm thinking that the remote
site would use telnet-to-a-high-port to reach the server... likely a 1- or
2-port console server, triggering off the DTR to establish a connection to
a known destination automatically.

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.

Best regards,

-Z-

--
ConsoleTeam - Support and training services for Conserver users.
www.conserver.com/consoles/
consoleteam.blogspot.com
- - - - - - - -
www.ncry.org
www.d4tm.org
www.hackerdojo.com
Re: How to "bridge" a serial connection over the Internet? [ In reply to ]
Digi sells an EtherLite box that we're proofing out for purposes of virtualizing (VMware) some modem-hanger servers.

Rob++

----- Original Message -----
> From: "Zonker" <consoleteam@gmail.com>
> To: zonker@conserver.com, users@conserver.com
> Sent: Monday, April 29, 2013 4:52:03 PM
> Subject: How to "bridge" a serial connection over the Internet?
>
>
>
>
>
> This is a bit of an unusual connection style. Any ideas how to
> achieve it? I think I'm suffering tunnel vision, and I could use a
> few clues to help expand my vision.
>
>
>
> At the remote site is a modem-like device. The remote site uses DHCP
> addressing, and NAT to get to the Internet, so I'm thinking that the
> remote site would use telnet-to-a-high-port to reach the server...
> likely a 1- or 2-port console server, triggering off the DTR to
> establish a connection to a known destination automatically.
>
> 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.
>
>
> Best regards,
>
>
> -Z-
>
>
> --
> ConsoleTeam - Support and training services for Conserver users.
> www.conserver.com/consoles/
> consoleteam.blogspot.com
> - - - - - - - -
> www.ncry.org
> www.d4tm.org
> www.hackerdojo.com
> _______________________________________________
> users mailing list
> users@conserver.com
> https://www.conserver.com/mailman/listinfo/users
>

--
pubkey: http://www.talgas.com/misc/rob_windsor-pubkey.txt
Internet: windsor@warthog.com
Life: Rob@Allen.Texas.USA.Earth

"They couldn't hit an elephant at this distance."
-- Major General John Sedgwick
_______________________________________________
users mailing list
users@conserver.com
https://www.conserver.com/mailman/listinfo/users
Re: How to "bridge" a serial connection over the Internet? [ In reply to ]
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
_______________________________________________
users mailing list
users@conserver.com
https://www.conserver.com/mailman/listinfo/users
Re: How to "bridge" a serial connection over the Internet? [ In reply to ]
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
>



--
ConsoleTeam - Support and training services for Conserver users.
www.conserver.com/consoles/
consoleteam.blogspot.com
- - - - - - - -
www.ncry.org
www.d4tm.org
www.hackerdojo.com
Re: How to "bridge" a serial connection over the Internet? [ In reply to ]
RaspberryPi with USB serial?


You can then write any code in Perl or Python that will monitor the
port and then make a connection back.

I would write a program on the conserver side that would map a remote
port to a pseudo tty. Conserver can then connect to that pseudo to
send and rx data. Or if it is one way simply use pipes or files.

Chris
_______________________________________________
users mailing list
users@conserver.com
https://www.conserver.com/mailman/listinfo/users