Home / server / Questions / 66690
Accepted
mr-euro
Asked: 2009-09-19 05:33:44 +0800 CST

telnet port forwarding

  • 772

Anyone knows if it is possible to setup port forwarding with a telnet client, like it is with SSH?

windows

3 Answers

  1. Best Answer

    You can do it with netcat, but it's a huge security hole:

    http://www.stearns.org/nc/

    http://forums.remote-exploit.org/newbie-area/5857-netcat-port-redirection.html

    mknod backpipe p
nc -l -p 80 0<backpipe | tee -a inflow | nc localhost 81 | tee -a outflow 1>backpipe

    FWIW, this is probably a profoundly bad idea.... make sure your firewall is tight as a drum...

    • 5

  2. Should be, yes...just forward the appropriate TCP port at the border you're doing the forwarding on. I don't know if you mean on the machine, forwarding using SSH, or forwarding through BRANDX router...

    EDIT: wait...are you saying using telnetd to forward ports like sshd does? No, telnet is purely a console application that gives shell access to a machine, as far as I know. I thought you meant can you port forward TELNET, not forward ports with telnetd.

    • 3

  3. Yes.

    machineA $ telnet machineB
  Username: someguy
  Password: whoIsGoingToGetHackedForRunningTelnet
machineB $ telnet machineC someport
   (whatever someport does)

    Have a program at either end of that that talks through the tunnel, and you're set. You could use expect, or your language of choice, to automate this. You'll only get one port at a time.

    But, why do you have telnet open on anything these days? :)

    • 0