Sending RS232 data through SSH

[poltergeisty]

Yep, you heard it right.

This really isn't decoder related, well sort of, in a sense. Figure I'll get a better response in here.

I have a program that will create a virtual com port and send the RS232 data over TCP, I.E, over a network. Well, I can pass RS232 data from one computer to another and actually control my scanner on a laptop that doesn't have a serial port. That was the first test. The second involves sending the "apparent" TCP data through a SSH tunnel. Went trough everything I could think of and was not successful in sending this kind of TCP traffic through a SSH tunnel. I currently have an open source firmware for my router that has a built in server for SSH. So I am no stranger to using it. I use it for road warrior Internet all the time. Even pass UltraVNC through SSH, no problem. But this RS232 to TCP isn't working. My only thought is that the data can not be encrypted in SSH. My next course of action is a VPN.




Any thoughts? I can upload some captured packets from wireshark or another sniffer I use. I'm using putty btw.

[poltergeisty]

*Bump

[shaft]

I didnt catch this the first time around, so thanks for bumping it.

I wouldnt think it would matter if you sent the traffic within the SSH tunnel. I dont see how VPN would make a difference since your essentially doing the same thing.

Can you do port fowarding in Putty? I use SecrureCRT for my SSH/telnet app. Within SecureCRT you can do port fowarding of applications within the SSH tunnel. For example, I can route my IRC traffic over the SSH tunnel to a server at my house.

[poltergeisty]

Yes, I can port forward. It strange because I do route VNC and E-mail thorough SSH, but the converted rs232 traffic which is TCP can't seem to go through. It may just be how I'm routing the traffic from the virtual com port through putty.

So it should work? Okay, cool. I'll try some other things here and see what happens.

SecureCRT looks just like putty. I'll have to give that a try. http://en.wikipedia.org/wiki/PuTTY

[mtindor]

What's the program called that is actinga a a virtual comport and allowing you to send the RS232 data over TCP/IP?

mike

[poltergeisty]

Well, I figured it out last night. I had the settings right, however it was only one important option that caused the virtual com port to fail. I enabled the option to create a connection even if not connected, or whatever it was called. Now it works! There are small things to consider though. Like starting the scanner software before creating a virtual com port will fail a SSH tunnel. So you must make the virtual com port first. Sounds like common sense, but it's more than that. I'm tunneling with SSH and confirmed with a network sniffer. That's cool for me because I have a built in SSH server in my router. The router is flashed with an alternative firmware. True nerd states has been obtained here. Hey, it saves power! I don't have to run another computer as a Linux box for SSH.

This is a great little VOIP app (uses UDP) to use instead of skype. I have a couple of other little apps that will send voice over TCP instead, but I need to test them. If all goes well, I should be able to send the voice traffic over SSH as well. So then I'll have scanner and voice encrypted using minimal bandwidth as compared to using UltraVNC. Except now with the use of SSH, the overhead adds about ten times more data. Normal transfer of RS232 to TCP is about 1.5-2.0 Kbits/sec. With SSH, it jumps to about 19Kbits/sec. Guess I'm picky.

My original use was with UltraVNC, however that is a slow and cumbersome. Great for fixing any problems on the remote computer though! Getting at the source of remote scanning was what I wanted, and RS232 to TCP was the right alternative.



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Instructions on what I did here are in the .pdf Hope you can understand it.

Use this as the com port to TCP proxy You need that to send the scanner's data through TCP. Another app which has the ability to be customized is SerProxy You can open multiple instances of the first app, Digibit, or configure SerProxy to run multiple com ports and the like in the .cfg file. The readme file in the SerProxy folder may have to be renamed with the .txt to read it.

This is the virtual com port app you run this on the computer that doesn't have a com port. In my case a laptop. I created a virtual com port in the laptop and then started the scanner software. It is like the scanner software never new a com port existed. . Wireless networking to its fullest potential I say!