Overview

Automatic SSH Tunnel is a Python script which can be used to create a Reverse SSH Tunnel between multiple computers running Linux and a centralized server.

Licensed under the MIT License - https://opensource.org/licenses/MIT

Features

• Automatically configures and runs openssh to set-up a reverse ssh connection during boot-up

• Automatically generates ssh keys

• No need to store the server's password

• Works with Debian-based systems, including Ubuntu

• 3-step configuration wizard that requires less than 1 minute to set-up

System requirements

• These instructions were tested on Ubuntu 15.10, Ubuntu 14.04.3, and Raspbian Jessie (Raspberry Pi)

• The installation script automatically installs openssh-server with Apt

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Animated Tutorial

   
 
 
 
 
 
   
 
 
 
 
 
 

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Getting started

Download

Clone the latest repository version from Github (recommended):
$ git clone https://github.com/facerecog/auto-ssh-tunnel.git

Alternatively, download the .tar.gz file from the top of this page and unpack it:
$ wget https://github.com/facerecog/auto-ssh-tunnel/tarball/master -O - | tar -xz

Now cd into the newly extracted directory.

Installation

Additional instructions for Mac OS X Users

Go to:
System Preferences > Sharing. Turn on "Remote Login". Allow access for "All Users".  

1. Run configuration.py to specify the port, username, and IP address of the SSH server:
   $ python configure.py <port> <username> <ip address>

2. Run the following command:
   $ sudo python setup.py install

The installation will proceed automatically. If successful, the output of all the commands should roughly show:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
openssh-server is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 118 not upgraded.
[*] Installing autossh client...
[*] Installing autossh as startup application...
mkdir: cannot create directory ‘.ssh’: File exists
yes: standard output: Broken pipe
yes: write error
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): priv_key already exists.
Overwrite (y/n)? [*] Copying SSH-Keys file over to server...
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
"<username>@<ip address>" 's password: 
Number of key(s) added: 1

Now try logging into the machine, with:   "ssh ' "<username>@<ip address>" '"
and check to make sure that only the key(s) you wanted were added.

[*] Installing private keys inside protected folder...
yes: standard output: Broken pipe
yes: write error
[*] Moving autossh client into the /usr/local/bin/ directory...
[*] Moving private key to /etc/auto-ssh-tunnel/
mkdir: cannot create directory ‘/etc/auto-ssh-tunnel’: File exists
yes: standard output: Broken pipe
yes: write error

[*] We are now finished with the installation! Restart the client to complete the installation. To run autossh, input connect.py on the terminal.

Also there is a systemd service file to start the connection on boot.

sudo cp reverse-tunnel.service /etc/systemd/system/

sudo systemctl enable reverse-tunnel.service

sudo systemctl daemon-reload

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How the script works

During installation, the script will automatically append the following lines to /etc/ssh/ssh_config:

ServerAliveInterval 30
ServerAliveCountMax 4

It will also append the following to /etc/ssh/sshd_config

ClientAliveInterval 30
ClientAliveCountMax 4

Upon boot, the client will run connect.py, which sets up a reverse ssh tunnel. The server may now ssh into the client even if the client resides behind a NAT firewall.

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Verify that it works

• From the client, ssh into your server:
  $ ssh <rootname>@<ip address>

• Once in, connect back to your client:
  $ ssh <your username>@localhost -p <port number specified as above>

• If successful, you have just ssh-ed back into your client. Congratulations and enjoy!

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Reverse SSH Tunnel Diagram

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Uninstall

To uninstall: $ sudo rm -rf /etc/init.d/connect.py /etc/auto-ssh-tunnel /usr/local/bin/connect.py /System/Library/StartupItems/auto-ssh-tunnel/

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Support

If you want to support this project, please consider reaching out to me via [email protected]

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Property of Facerecog Asia Pte. Ltd. and 26 Factorial