I have a client/server application that work over a telnet connection, and it does not support SSH. Basically the client opens a telnet connection to the server, which starts a specific shell, and the client sends commands over the telnet connection to that shell. The problem is that I need to make this work over a ssh connection, and the remote server does not have telnet services, so I cannot use a tunnel over the ssh connection. I need some kind of telnet emulator that will offer a telnet endpoint to the client, while connecting through ssh to the server. Is there any way to do this?


  • When can’t improve the client and it requires a telnet connection you will probably need to install a telnet server. You can then use port forwarding over SSH to ensure transport encryption (or preferably set up a VPN connection to do the same) and won’t even need to open up the telnet port to the public at large.
    – HBruijn
    May 19, 2019 at 9:24
  • I know, but installing a telnet server is not an option. That’s why I’m looking for a way to emulate a telnet server that send all commands through ssh to the shell in the remote server. May 19, 2019 at 9:28
  • Why does it need to be ssh, to encrypt it? telnet over TLS (telnets) is a thing. Does the application implement its own telnet server and/or client, or does it just run whatever telnet client binary is available? May 19, 2019 at 17:25
  • The application inplements it’s own telnet client, and on the server side the only connection I’ve got available is SSH May 19, 2019 at 23:31

1 Answer 1


That's a normal case for port forwarding over ssh.

A server <ip> has ssh endpoint opened and an application server listening on Telnet port 23.

A client has an application client which should connect to <ip>:23. Also client has nothing listening on port 23.

Let's establish port forwarding from server to client:

ssh -N -L 23: user@<ip> >/dev/null 2>&1 & 

Here we:

  • connect to the server <ip> as user user;
  • put ssh session into background;
  • redirect ssh session's output into /dev/null to avoid any messages on console;
  • forward port 23 from the server's localhost to the client (your application server should listen on all IP interfaces, including

Now application client should connect to the address to work with the application server.


As per explanations, we have a telnet only capable client software and ssh only capable server. And client should be able to access the server.

As it happens, such solution does exist. From manual:

SSH/Telnet gateway

In the Telnet-DeleGate (DeleGate server for Telnet clients), a host name prefixed with "-ssh" and "." (as "-ssh.host") implies a SSH server on the host. In access to such a server, Telnet-DeleGate works as a gateway between the SSH server and a Telnet client. For example, using a Telnet-DeleGate configured like follows, Telnet clients can login to a SSH server on host as user as follows:

% delegated -P8023 SERVER=telnet://-ssh
% telnet -l user@host localhost 8023

Meet DeleGate

  • That would be ok, except for the fact that telnet is no running on the server. That’s why I need to emulate a telnet and send the commands the client generate to the server’s she’ll using ssh May 21, 2019 at 0:04
  • @JoseLMartinez-Avial When your server application is started, which port is it listening on? Also what OS is on the server? May 21, 2019 at 0:53
  • There is no server as such. The applications connects through telnet and runs shell commands and programs. So is no a server per se, just a command shell. The OS is Solaris May 21, 2019 at 9:44
  • @JoseLMartinez-Avial Posted an update. Exactly what you were looking for... May 21, 2019 at 12:32

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