Not able to do port forwarding with multiple hosts

Question

I have one hop between my local machine and the machine I want to access some remote port. I am trying following thing. But doesn't seem to work.

From remote machine, I want port 9443 to open on my local machine. The port 9443 is already being used by

local_machine --> hop --> remote_machine

Login to hop machine and run following command

 ssh -N gshah03@remote_machine -L 8080:localhost:9443 -4

Now from my local machine. issue following command.

ssh -N gshah03@hop-L 9443:localhost:8080

However, on first step I am getting following error.

debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
debug1: Connection to port 8080 forwarding to 127.0.0.1 port 9443 requested.
debug1: channel 1: new [direct-tcpip]
channel 1: open failed: connect failed: Connection refused
debug1: channel 1: free: direct-tcpip: listening port 8080 for 127.0.0.1 port 9443, connect from 127.0.0.1 port 33558 to 127.0.0.1 port 8080, nchannels 2
debug1: Connection to port 8080 forwarding to 127.0.0.1 port 9443 requested.
debug1: channel 1: new [direct-tcpip]
channel 1: open failed: connect failed: Connection refused
debug1: channel 1: free: direct-tcpip: listening port 8080 for 127.0.0.1 port 9443, connect from 127.0.0.1 port 33562 to 127.0.0.1 port 8080, nchannels 2

Gerard H. Pille · Answer 1 · 2020-04-24T16:34:02.173

0

ssh -N gshah03@remote_machine -L 8080:localhost:9443 -4

In this case, "localhost" IS remote_machine.

If I understand what you want, it should be

ssh -N gshah03@remote_machine -L 8080:local_machine:9443 -4

But that would mean the remote_machine doesn't need the hop to connect to your system.

If you just want 9443 on local machine to connect to 9443 on the remote machine, the following is sufficient:

ssh -N gshah03@hop-L 9443:remote_machine:9443

edited Apr 24 '20 at 16:34

answered Apr 24 '20 at 15:21

Gerard H. Pille

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The first command I am running after i do ssh to `hop` machine. machine inbetween my `laptop` and `remote machine` I want access to. – Gaurang Shah Apr 24 '20 at 15:27
And I can't even do `ssh` to `remote machine` without first doing `ssh` to `hop` machine. – Gaurang Shah Apr 24 '20 at 15:28
I got that. Do you want remote machine to connect to itself? Because "localhost" equals "remote_machine". – Gerard H. Pille Apr 24 '20 at 16:26
nope. I just want.. `my laptop` --> `Hop` --> `remote machine` – Gaurang Shah Apr 24 '20 at 16:27
That sounds quite different than "From remote machine, I want port 9443 to open on my local machine". I've edited my answer. – Gerard H. Pille Apr 24 '20 at 16:34
`9443` is already in use by some other process on `hop` machine. How to handle this? – Gaurang Shah Apr 27 '20 at 17:10
But we're not using 9443 on the hop. We're linking 9443 local to 9443 remote. On the hop, only the ssh port is used (probably 22). Perhaps 9443 is locally used? – Gerard H. Pille Apr 27 '20 at 17:33

Not able to do port forwarding with multiple hosts

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