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Telnet Server that works with Serial Port

Posted on 1997-12-14
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Last Modified: 2013-12-28
I am looking for software that will be working as Terminal Server.
I have a Switch that can be configured from Terminal connected to it by serial cable (RS232). I want to connect PC instead of this terminal, so I am looking for software that allows to make Telnet session with device connected to Serial Port. It will be great if this software will also have Telnet Server option ( I can access the serial connected device from another PC over the network (TCP/IP)).
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Question by:hefetz
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Author Comment

by:hefetz
ID: 1787498
Adjusted points to 200
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by:drcheap
ID: 1787499
I've got exactly what you need...

Seattle Labs makes a Telnet Server (SLnet) that will allow you to have multiple users telnet into your machine over TCP/IP, and you can specify ANY command shell on a per user basis.  There are also a bunch of other great features available.

I have tested about 5 other telnet daemons, and this is the *best* one I have seen.  It works great!

They also offer a program called SLink that works with SLnet to allow your machine to be a terminal server.  This would let any serail device connect via the RS232 .. or even multiple machines is possible :)

Go check it out at:  http://www.seattlelab.com/
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Author Comment

by:hefetz
ID: 1787500
Thank you for your reply.
I already tried this product.
What I did is : connected the PC to a modem by RS232. This PC has SLink & SLnet installed, and I wanted to access this modem from a remote Client's PC, using Telnet.
I was not able to access the modem so I if the configuration was wrong or the product does not provide this feature.
If you know what I can do I will appreciate your help.
Thanks.
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by:drcheap
ID: 1787501
So, what you are saying is you would telnet into this PC via the Internet (via a LAN or whatever) and then "dial out" on the modem that is attached to it?

If this is the case, then the only way to do that is to run a text-based terminal program.  Now the difficulty there is I don't think there is such a thing for NT :(  And DOS term programs won't work because they try to write either directly to the port, or use BIOS .. both of which NT does not allow.  SO, if the above is what you are wanting to do, then I don't think it's possible.
Although, you could use some remote access software (either that built into NT or some third party stuff) and run a windows based terminal program...

Please give a little more detail as to the type of connection bringing you into the PC, and maybe the setup of what hardware you are working with.  No such thing as too much info :)

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Expert Comment

by:biyiadeniran
ID: 1787502
This information may be of use:

The Telnet Server tool in the Microsoft Windows NT Server Resource Kit version 4.0 provides basic TCP/IP Telnet Server functionality. A computer running the Telnet Server tool under Windows NT Server can support connections from various TCP/IP Telnet clients, including UNIX-based and Windows NT–based computers.
The Telnet Server tool supports command-line execution of commands that normally can be run in the command window—for example, TCP/IP tool or MS-DOS commands. A command you enter at the remote Telnet client console (computer) runs on the Windows NT– based Telnet Server computer. The Telnet Server then sends the results of the command back to the remote Telnet client computer.
When you install Windows NT Server or Windows NT Workstation, a Telnet client is automatically installed in the Accessories folder. You use the Telnet client to connect to another computer running a TCP/IP– based Telnet server—for example, the Windows NT– based Telnet server, or a UNIX-based Telnet server.
Each Telnet client session started on the Windows NT–based Telnet server is allocated a console session that runs in the remote user’s desktop context and that does not interfere with any local user sessions on the computer running Telnet Server under Windows NT. At the start of a Telnet session, the remote Telnet client must provide a user name and password to log on to the Windows NT– based Telnet Server. This information is used to create a console session with the security attributes of the user. For example, an administrator can log on to a computer running Windows NT Workstation, start the Windows NT– based Telnet client, connect to the computer running Windows NT Server with the Telnet Server tool, and run command-line scripts to add users, services, and so on.
 
Note   The Telnet Server tool provided with the Microsoft Windows NT Server Resource Kit version 4.0 is beta software. It does not support terminal types and provides only basic TTY functionality. To ask questions about the Telnet Server tool, contact rkinput@microsoft.com.
 
You can also visit http://www.windows95.com/apps/terminals.html to get some downloads e.g. MxTNT-Terminal Server.
Good Luck and Happy new year.
'Biyi
 

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Expert Comment

by:drcheap
ID: 1787503
What the hell was that, a quote from some Micro$oft bulletin or manual?

He is not looking for a telnet daemon..that part was already established.

Even using the MS telnet server, which never worked for me..beta software..go figure, he would not be able to access an outgoing modem connection since there is no text-based terminal program for NT.  

If someone finds one of these it would solvr hefetz's problem and I would love a copy too :)

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Author Comment

by:hefetz
ID: 1787504
My goal is to be able to communicate with a telephony switch which is connected to a PC with NT on it from any other PC on the LAN. I was thinking of using the Telnet server on the NT connected to the switch, and to use telnet terminals from remote PC's on the network, so users can communicate from they're own computers and won't have to go directly to the NT server every time. I was trying to simulate a switch using an ordinary modem.
So, that's all the info I have, and I'm still searcing for the right product.
Thanx for all your help.
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by:drcheap
ID: 1787505
How does one normally access this switch when they go to the NT machine?  Through a command prompt?  Some terminal program?  Special software?  Something else?


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by:heiko
ID: 1787506
I think thats a solution for you:

install on your NT machiine connected to your switch a COM sharing software like SAPs, so that you can access from any machine on your network to this interface via network. so you can access to your switch as installed local to each machine.
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Author Comment

by:hefetz
ID: 1787507
We access the switch with telnet.
That's why I can't use SAPS - cause that uses a terminal and
doesn't let me use the telnet session.
What I need is a software product that will replace a terminal server.
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by:heiko
ID: 1787508
sorry i don't understand why you have to connect via telnet.
your switch does not provide a interface for TCP/IP. the only you need is a transport for ascii characters via network. why via telnet an not via RPC? both are based on TCT/IP and also available for your entrie network.

software you are searching for is a telnet deamon which redircts a dedicated COM port. (right?) ok i will lock for, but at the moment i dont know about such.
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Author Comment

by:hefetz
ID: 1787509
We have to use Telnet cause some of the switches support only Telnet, and this is the only client interface we can use (we want all clients to have the same interface).
The software we are looking for is what you described - a telnet deamon which redirects a dedicated COM port.
Maybe a telnet server OCX or API.
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Expert Comment

by:drcheap
ID: 1787510
Here's a thought...

Put an OS that allows direct port I/O on the server, in this case I think you'd have to go with Win95 (yuck).  Put SLNet on the machine, and a over simplified DOS based terminal program.  For SLNet's settings, use command.com /C as the default shell with he, and the terminal program as the command line.  

With a little tweaking and stuff, you could have the same effect as a telnet daemon that does nothing more than present the client with whatever is on that port, then auto-exit (disconnects too) when they are done.  
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Expert Comment

by:heiko
ID: 1787511
Telnet from Chameleon package is able to use both async and network with same interface. this is your chance to use a normal COM redirector and same frontend for all switches you have.

Good luck
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Author Comment

by:hefetz
ID: 1787512
Thanks for the advice.
I'll check it out. I've already made contact with them and the package is on it's way to me.

I'll let you know if it works.

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by:drcheap
ID: 1787513
I just accomplished something AMAZING today...and I did it almost by randomness!  What it is?  And why am I saying it here?  Read on...

I can now TELNET into my NT machine from other comptuers on my LAN, as well as from anywhere in the world (IP ranges selectable even) and login to be presented with a TERMINAL session with the MODEM in my computer!  Then, I am able to dial out to anywhere I want to as if I were using the modem from a DOS machine!

I can also change to an external serial port and access whatever may be on it at the time...could be a terminal server or another computer, or any serial device :)

So...I have my computer doing exactly what you want yours to do.

Unlock the question and I will explain the setup I have going that allows this to work.
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Author Comment

by:hefetz
ID: 1787514
please, I'de love to hear all about it.
Thanxs
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Accepted Solution

by:
drcheap earned 200 total points
ID: 1787515
Okay, here goes...


Hardware/Software Involved:

NT Workstation 4.0
Internet via LAN connected directly to the 'net
Seattle Labs Telnet Server v2.2
Cirrus Logic 56K x2 V/F/D modem on COM2/IRQ3
Telix 3.22 for DOS  (the interesting part)


What it looks like:

telnet xxx.xxx.xxx.xxx
logon: dialout
password: ********
Use Color Codes? Yes
[at this point the terminal session with my modem is activated]


How it is setup:

In Control Panel -> Ports
COM2 is set with appropriate I/O, IRQ, bps, etc.
Port settings in Telix to match these
NT user account "dialout" with home directory c:\telix
SLNet user account "dialout" default shell c:\telix\telix.exe
SLNet user account "dialout" startup directory c:\telix


Known bugs:

Can't exit Telix when done because I can't seem to send ALT-X through telnet.  Not a big deal, just close telnet connection and SLNet kills the process after a minute or two.  This is good though, prevents ALT-J for shell to DOS (still couldn't do much there anyway because of account restrictions).

16bit app hogs CPU time...need a Win32 character-based comm program!


This could be adapted to your situation by having Telix use the serial port that your device is hooked to, and setting that one up in CPanel->Ports.

I'd let you "try out" mine so you can see it, but that's a little risky on my part -- Don't need any huge phone bills :)

One of the cooler features is that since SLNet supports IP include/exclude ranges, you can have even more control over who can access your device!

I hope that you can get this to work out...and I get a cookie for the idea.  Make that a dozen of 'em!

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