SSHTunnel : SSH Tunnels To Remote Server

SSHTunnel is a tool for SSH tunnels to remote server.

Installation

sshtunnel is on PyPI, so simply run:

pip install sshtunnel

easy_install sshtunnel

conda install -c conda-forge sshtunnel

to have it installed in your environment.

For installing from source, clone the repo and run:

python setup.py install

Also Read – DetectionLab : Vagrant & Packer Scripts To Build A Lab Environment

Testing The Package

In order to run the tests you first need tox and run:

python setup.py test

Usage Scenarios

One of the typical scenarios where sshtunnel is helpful is depicted in the figure below. User may need to connect a port of a remote server (i.e. 8080) where only SSH port (usually port 22) is reachable.

----------------------------------------------------------------------

                            |
-------------+              |    +----------+
    LOCAL    |              |    |  REMOTE  | :22 SSH
    CLIENT   | <== SSH ========> |  SERVER  | :8080 web service
-------------+              |    +----------+
                            |
                         FIREWALL (only port 22 is open)

----------------------------------------------------------------------

Fig1: How to connect to a service blocked by a firewall through SSH tunnel.

If allowed by the SSH server, it is also possible to reach a private server (from the perspective of REMOTE SERVER) not directly visible from the outside (LOCAL CLIENT‘s perspective).

----------------------------------------------------------------------

                            |
-------------+              |    +----------+               +---------
    LOCAL    |              |    |  REMOTE  |               | PRIVATE
    CLIENT   | <== SSH ========> |  SERVER  | <== local ==> | SERVER
-------------+              |    +----------+               +---------
                            |
                         FIREWALL (only port 443 is open)

----------------------------------------------------------------------

Fig2: How to connect to PRIVATE SERVER through SSH tunnel.

Usage Examples

API allows either initializing the tunnel and starting it or using a with context, which will take care of starting and stopping the tunnel:

Example 1

Code corresponding to Fig1 above follows, given remote server’s address is pahaz.urfuclub.ru, password authentication and randomly assigned local bind port.

from sshtunnel import SSHTunnelForwarder

server = SSHTunnelForwarder(
    'pahaz.urfuclub.ru',
    ssh_username="pahaz",
    ssh_password="secret",
    remote_bind_address=('127.0.0.1', 8080)
)

server.start()

print(server.local_bind_port)  # show assigned local port
# work with `SECRET SERVICE` through `server.local_bind_port`.

server.stop()

Example 2

Example of a port forwarding to a private server not directly reachable, assuming password protected pkey authentication, remote server’s SSH service is listening on port 443 and that port is open in the firewall (Fig2):

import paramiko
import sshtunnel

with sshtunnel.open_tunnel(
    (REMOTE_SERVER_IP, 443),
    ssh_username="",
    ssh_pkey="/var/ssh/rsa_key",
    ssh_private_key_password="secret",
    remote_bind_address=(PRIVATE_SERVER_IP, 22),
    local_bind_address=('0.0.0.0', 10022)
) as tunnel:
    client = paramiko.SSHClient()
    client.load_system_host_keys()
    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    client.connect('127.0.0.1', 10022)
    # do some operations with client session
    client.close()

print('FINISH!')

Example 3

Example of a port forwarding for the Vagrant MySQL local port:

from sshtunnel import open_tunnel
from time import sleep

with open_tunnel(
    ('localhost', 2222),
    ssh_username="vagrant",
    ssh_password="vagrant",
    remote_bind_address=('127.0.0.1', 3306)
) as server:

    print(server.local_bind_port)
    while True:
        # press Ctrl-C for stopping
        sleep(1)

print('FINISH!')

Or simply using the CLI:

(bash)$ python -m sshtunnel -U vagrant -P vagrant -L :3306 -R 127.0.0.1:3306 -p 2222 localhost

Example 4

Opening an SSH session jumping over two tunnels. SSH transport and tunnels will be daemonised, which will not wait for the connections to stop at close time.

import sshtunnel
from paramiko import SSHClient


with sshtunnel.open_tunnel(
    ssh_address_or_host=('GW1_ip', 20022),
    remote_bind_address=('GW2_ip', 22),
    block_on_close=False
) as tunnel1:
    print('Connection to tunnel1 (GW1_ip:GW1_port) OK...')
    with sshtunnel.open_tunnel(
        ssh_address_or_host=('localhost', tunnel1.local_bind_port),
        remote_bind_address=('target_ip', 22),
        ssh_username='GW2_user',
        ssh_password='GW2_pwd',
        block_on_close=False
    ) as tunnel2:
        print('Connection to tunnel2 (GW2_ip:GW2_port) OK...')
        with SSHClient() as ssh:
            ssh.connect('localhost',
                port=tunnel2.local_bind_port,
                username='target_user',
                password='target_pwd',
            )
            ssh.exec_command(...)

CLI Usage

$ sshtunnel --help
usage: sshtunnel [-h] [-U SSH_USERNAME] [-p SSH_PORT] [-P SSH_PASSWORD] -R
                 IP:PORT [IP:PORT ...] [-L [IP:PORT [IP:PORT ...]]]
                 [-k SSH_HOST_KEY] [-K KEY_FILE] [-S KEY_PASSWORD] [-t] [-v]
                 [-V] [-x IP:PORT] [-c SSH_CONFIG_FILE] [-z] [-n] [-d [FOLDER [FOLDER ...]]]
                 ssh_address

Pure python ssh tunnel utils
Version 0.1.5

positional arguments:
  ssh_address           SSH server IP address (GW for SSH tunnels)
                        set with "-- ssh_address" if immediately after -R or -L

optional arguments:
  -h, --help            show this help message and exit
  -U SSH_USERNAME, --username SSH_USERNAME
                        SSH server account username
  -p SSH_PORT, --server_port SSH_PORT
                        SSH server TCP port (default: 22)
  -P SSH_PASSWORD, --password SSH_PASSWORD
                        SSH server account password
  -R IP:PORT [IP:PORT ...], --remote_bind_address IP:PORT [IP:PORT ...]
                        Remote bind address sequence: ip_1:port_1 ip_2:port_2 ... ip_n:port_n
                        Equivalent to ssh -Lxxxx:IP_ADDRESS:PORT
                        If port is omitted, defaults to 22.
                        Example: -R 10.10.10.10: 10.10.10.10:5900
  -L [IP:PORT [IP:PORT ...]], --local_bind_address [IP:PORT [IP:PORT ...]]
                        Local bind address sequence: ip_1:port_1 ip_2:port_2 ... ip_n:port_n
                        Elements may also be valid UNIX socket domains:
                        /tmp/foo.sock /tmp/bar.sock ... /tmp/baz.sock
                        Equivalent to ssh -LPORT:xxxxxxxxx:xxxx, being the local IP address optional.
                        By default it will listen in all interfaces (0.0.0.0) and choose a random port.
                        Example: -L :40000
  -k SSH_HOST_KEY, --ssh_host_key SSH_HOST_KEY
                        Gateway's host key
  -K KEY_FILE, --private_key_file KEY_FILE
                        RSA/DSS/ECDSA private key file
  -S KEY_PASSWORD, --private_key_password KEY_PASSWORD
                        RSA/DSS/ECDSA private key password
  -t, --threaded        Allow concurrent connections to each tunnel
  -v, --verbose         Increase output verbosity (default: ERROR)
  -V, --version         Show version number and quit
  -x IP:PORT, --proxy IP:PORT
                        IP and port of SSH proxy to destination
  -c SSH_CONFIG_FILE, --config SSH_CONFIG_FILE
                        SSH configuration file, defaults to ~/.ssh/config
  -z, --compress        Request server for compression over SSH transport
  -n, --noagent         Disable looking for keys from an SSH agent
  -d [FOLDER [FOLDER ...]], --host_pkey_directories [FOLDER [FOLDER ...]]
                        List of directories where SSH pkeys (in the format `id_*`) may be found

Credit: Pahaz

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