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Last pushed: 2 years ago
Short Description
A ssh based VPN in a Docker container: Jump host for port forwarding and SOCKS proxy, no shell.
Full Description

docker-ssh-vpn-jump-host

A secured ssh based VPN in a Docker container. Works only as
jump host for port forwarding and SOCKS proxy but provides no shell.

It can either be used to access services on a remote host or
a remote access in a secure way.

Or it can be used to publish services inside a docker container
with ssh. I this case, there should be at least two docker
ontainers: One running the service you want to access from the
outside and one running the ssh service.

The big advantage of having ssh in a separate Docker container is that
the ssh container can be kept at the most current version while the rest
of the system can stay at a stable state. So if there are some security
updates, it is sufficient to only update the ssh Docker container and
keep the rest of the system untouched.

With the ssh Docker container it is also possible to update ssh from remote
without risking to lock yourself out. Just spawn two instances of the ssh
Docker container, then connect to the first and update the second and
then vice versa. So there is always a backup in case the update fails and
ssh won't start in the updated container.

Idea: SSH VPN jump host for port forwarding

This docker file provides a pure jump host. This means it
can only be used to connect to other servers using
ssh port fowarding. It has no shell available and
cannot run any commands.

Connecting

Connect from Linux

Open the command line and run

  1. ssh -N -L xxx:nnnnnn:yyy -p 22022 vpn@name-of-server

    Where

Option Description
nnnnnn:yyy The remote server you want to access
xxx The local port number
name-of-server The name of the jump gateway server

You can then access the remote server on port xxx on your
local system.

  1. ssh -N -D 1080 -p 22022 vpn@name-of-server

    You can then add "localhost:1080" as a socks 4 proxy to
    your local web browser. All traffic will be tunneled to
    the vpn gateway server.

Connect from Mac OS X

Install a current ssh version using homebrew:

    brew tap homebrew/dupes
    brew install openssh \
      --with-brewed-openssl --with-keychain-support

Then continue with the steps for Linux.

Connect from Windows

Attention: PuTTY does not support the required encryption
levels used on this server.

Connect using KiTTY SSH or MobaXTerm.

KiTTY SSH

Configure a new session with port forwarding. Under "SSH"
choose "Don't start a shell or command at all".

MobaXTerm

Create a new connection. Under "Advanced settings" choose
"Conncet through SSH gateway (jump host)"

Autossh

Instead of the plain command line ssh, you can also use autossh. Autossh automatically restarts the tunnel when the connection temporarily goes down. It is available to all major platforms (on Windows autossh is available as a Cygwin package and can even run as a Windows service).

News

Date Remark
2015-07-22 The provided configuration is already imune against the MaxAuthRetries attack.
2016-02-17 The provided configuration is probably safe against the GLibc getaddrinfo attack. Nevertheless all users are advised to rebuild the Docker image, so it fetches the fixes from Ubunutu 14.04 LTS. The patches are already in the LTS version, othere Ubuntu versions should follow soon.
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Owner
geggo98

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