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I would like to open a PuTTY terminal session on one machine which is physically connected to another machine via an ethernet cross-over cable. Ideally characters entered in the PuTTY terminal window on one machine would appear in the terminal window on the other machine.

Is this possible?

Hardware & Configuration:

I disabled wireless adapters on each machine and went to: Control Panel / Network and Internet / Network and Sharing Center / Chose Local Area Connection / Properties / Select TCP/IPv4 / Chose Properties button and set the addresses accordingly. Settings common to each machine were:

  1. Subnet Mask: 255.255.255.0
  2. Default Gateway: 192.168.1.0
  3. Preferred DNS Server: 8.8.8.8
  4. Alternate DNS Server: 8.8.4.4

Machine 1: Windows 7, 64-bit, SP1. Static IP address is 192.168.1.4

Machine 1: Windows 7 (embedded), 32-bit. Static IP address is 192.168.1.5

Both machines have had their Windows Firewalls disabled.

I lied when I said the devices were physically connected via an ethernet cross-over cable. Rather, each machine is connected to an ethernet/RF modem (have been assigned the static IP addresses 192.168.1.2 and 192.168.1.3) via a standard network cable. The modems should be transparent, so for all intents and purposes the two machines should be connected via ethernet.

Approach & Attempts at Solution

  1. On each machine, at the command prompt, I can ping each of the following IP addresses. 192.168.1.2, 192.168.1.3, 192.168.1.4, 192.168.1.5. Confirmed. We see small ping transmission times associated with the local ethernet adapter IP address and local modem, longer times associated with the transmission to the IP addresses on the other side of the RF link.

  2. I do: Search / choose Network / and see two and only two computers on each machine.

  3. On both machines, I launch a PuTTY session, choose SSH, enter the appropriate IP address (192.168.1.5 from 192.168.1.4 and vice-versa) and use the default port value of 22. I also disable authentication (not sure if this makes any difference) by going to SSH / Auth / and choose bypass authentication entirely. When I attempt to launch the PuTTY session, I get the Network error: Connection refused message. Confirmed.

  4. So then I ask the question: How do we know that port 22 is the right port number? I go to the opposite machine, at the command prompt type: netstat -a. I see the following:

    a. Under TCP protocol, and LISTENING state I see 0.0.0.0:7, 0.0.0.0:9, etc. for port numbers 7, 9, 13, 17, 19, 80, etc. No port 22 is observed.

    b. Also under TCP protocol, and LISTENING state I see 192.168.1.5:139. This strikes me as the most encouraging port number to try connecting through/over. It turns out that both machines are of state LISTENING on port 139.

    c. Further down the list under UDP protocol, but with the state field un-populated, I see 192.168.1.5:137, 192.168.1.5:138, etc. for ports 137, 138, 520, 5353.

  5. Next I try going back to establishing a connection in PuTTY, this time using port 139. This time I get the message Network error: Software caused connection abort. The error presents itself 30 s or so after attempting the connection. I do the same from the other machine and get the message: Network error: connection timeout.

  6. If I run netstat -a at the command prompt shortly after trying to connect to the other machine in PuTTY, I saw an entry (Protocol | Local Address | Foreign Address | State) which was

    TCP | 192.168.1.5:49328 | 19.168.1.4:netbios-ssn | SYN_SENT

    And have seen a state value of ESTABLISHED where the foreign address corresponds to the machine I was trying to establish the connection with.

I guess, firstly, I'll re-iterate the central question:

Can I send characters from one terminal session/machine to the other in this way?

If so, any thoughts and/or comments on how to establish a reliable connection would be greatly appreciated.

Chris

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  1. No, you can not do this the way you described your setup as Windows has no ssh server component which would listen on port 22.

  2. You could open a remote powershell connection from one computer to the other but this also would not show on the computer you are connected to

  3. A kind of solution where you could connect to another computer and see the same screen on both would be:

    a. remote assistance
    b. VNC server on the computer you would connect to with a VNC client

The solutions mentioned in point 3 are not a terminal copy you asked for, but a way to share and (if allowed) control a host.

  • @fixer1234 - Yeah, seems so. So the answer should be: No you can not do this the way you described your setup. Should I change the answer to this? – Zina Feb 13 '16 at 20:46
  • Thanks both for the comments. I'm not entirely convinced by the answer or at least still have many questions. For instance, why exactly does PuTTY issue the Connection refused message? What is so special about port 22 or why can't I establish a connection on a different port number (for instance one of those which were LISTENING) ? – John Chris Feb 14 '16 at 21:48
  • I suspect I should create a different question. Ultimately, my goal is to issue commands (ASCII strings) from a terminal session running on machine A (master). An application running on machine B (slave) will listen for commands on a port, interpret the commands and execute appropriate action. This mode of operation works fine when we interface with the RS-232 ports of the RF modems. How can this be done by interfacing with the ethernet ports of the modems? – John Chris Feb 14 '16 at 21:58
  • PuTTY is a client appliction which can connect to terminal server via different connection types (raw, telnet, rlogin, ssh, serial). Port 22 is the default port for ssh (which can be changed). To connect to a server with ssh the server has to have a running ssh server application/service. ssh is mostly used on *nix and on network devices (eg cisco routers, switches). To successfully connect from machine A to B the two need as minimum a server side and a client side. Eg a web server and a web browser, the first listening on port 80 and the browser asking for content on port 80. – Zina Feb 15 '16 at 9:17
  • So you can conect the computer through RS232 to the modem issue commands. I assume you use PuTTY via serial. And you want the same to achieve through the ethernet cable. For that to work your RF modem has to have an IP AND a service set up to accept communication to the admin part of it. You have to check the RF modems manual what management capabilities it has. After reading your comments it looks like you would need to create a server/client application to achieve what you described, as a terminal client on machine A needs a terminal server side on machine B. – Zina Feb 15 '16 at 9:17

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