1

I would like to establish a reverse SSH-tunnel (with OpenSSH_7.4 or newer). The purpose is to allow SSH-connections from a central server to multiple devices whose task it is (among others) to establish the tunnels. The central server has a known IP, while the devices do not.

I would usually do this in the following way on one of the devices

ssh -R "4001:server:22" -p 22 user@server

such that I can connect from the server to the device

ssh -p 4001 deviceuser@localhost

This works (and I do not need to know the IP-address of the device).

Now, I am not connecting a single device, but multiple, each of which creates a reverse tunnel and needs a separate port on the server. Furthermore, I want to connect repeatedly via ssh to each of them.

Thus, I had the idea to establish the reverse tunnel with a socket, like so:

ssh -R "~/tmp/device.sock:server:22" -p 22 user@server

In order to connect to the device from the server by

ssh -S ~/tmp/device.sock -p 22 deviceuser@device

I need the device's IP here, but that wouldn't be the major issue. However, I cannot seem to get that to work. The first command creates the socket, but with the second one I get errors such as

Control socket connect(/home/user/tmp/device.sock): Connection refused

The intended behaviour is that I can connect to the device through the tunnel, just like with the tunnel at port 4001 above, but based on the socket file. I cannot find any concise resources and wonder if, what I attempt, is in fact possible.

I assume that I could first create the tunnel to port 4001 and then an start an ssh control connection using a socket, but then I still need to use multiple ports on the server. There are enough ports available for my purposes, but I was hoping that there is a more elegant way to achieve this.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.