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Saturday, 3 September 2016

OpenVPN client's docker image


What is OpenVPN?

OpenVPN is an open-source software application that implements virtual private network (VPN) techniques for creating secure point-to-point or site-to-site connections in routed or bridged configurations and remote access facilities. It uses a custom security protocol that utilizes SSL/TLS for key exchange. It is capable of traversing network address translators (NATs) and firewalls.

How to use this image

This OpenVPN container was designed to be started first to provide a connection to other containers (using --net=container:vpn, see below).
NOTE: More than the basic privileges are needed for OpenVPN. With docker 1.2 or newer you can use the --cap-add=NET_ADMIN and --device /dev/net/tun options. Earlier versions, or with fig, and you'll have to run it in privileged mode.
NOTE 2: If you have connectivity issues, please see the DNS instructions below.
NOTE 3: If you need access to other non HTTP proxy-able ports, please see the Routing instructions below.
NOTE 4: If you have a VPN service that allows making local services available, you'll need to reuse the VPN container's network stack with the --net=container:vpn (replacing 'vpn' with what you named your instance of this container) when you launch the service in it's container.

Hosting an OpenVPN client instance

sudo cp /path/to/vpn.crt /some/path/vpn-ca.crt
sudo docker run -it --cap-add=NET_ADMIN --device /dev/net/tun --name vpn \
            -v /some/path:/vpn -d dperson/openvpn-client \
            -v 'vpn.server.name;username;password'
sudo docker restart vpn
Once it's up other containers can be started using it's network connection:
sudo docker run -it --net=container:vpn -d some/docker-container

Local Network access to services connecting to the internet through the VPN.

However to access them from your normal network (off the 'local' docker bridge), you'll also need to run a web proxy, like so:
sudo docker run -it --name web -p 80:80 -p 443:443 \
            --link vpn:<service_name> -d dperson/nginx \
            -w "http://<service_name>:<PORT>/<URI>;/<PATH>"
Which will start a Nginx web server on local ports 80 and 443, and proxy any requests under /<PATH> to the to http://<service_name>:<PORT>/<URI>. To use a concrete example:
sudo docker run -it --name bit --net=container:vpn -d dperson/transmission
sudo docker run -it --name web -p 80:80 -p 443:443 --link vpn:bit \
            -d dperson/nginx -w "http://bit:9091/transmission;/transmission"
For multiple services (non-existant 'foo' used as an example):
sudo docker run -it --name bit --net=container:vpn -d dperson/transmission
sudo docker run -it --name foo --net=container:vpn -d dperson/foo
sudo docker run -it --name web -p 80:80 -p 443:443 --link vpn:bit \
            --link vpn:foo -d dperson/nginx \
            -w "http://bit:9091/transmission;/transmission" \
            -w "http://foo:8000/foo;/foo"

Routing for local access to non HTTP proxy-able ports

The argument to the -r (route) command line argument must be your local network that you would connect to the server running the docker containers on. Running the following on your docker host should give you the correct network: ip route | awk '!/ (docker0|br-)/ && /src/ {print $1}'
sudo cp /path/to/vpn.crt /some/path/vpn-ca.crt
sudo docker run -it --cap-add=NET_ADMIN --device /dev/net/tun --name vpn \
            -v /some/path:/vpn -d dperson/openvpn-client \
            -r 192.168.1.0/24 -v 'vpn.server.name;username;password'
NOTE: if you don't use the -v to configure your VPN, then you'll have to make sure that redirect-gateway def1 is set, otherwise routing may not work.

Configuration

sudo docker run -it --rm dperson/openvpn-client -h

Usage: openvpn.sh [-opt] [command]
Options (fields in '[]' are optional, '<>' are required):
    -h          This help
    -d          Use the VPN provider's DNS resolvers
    -f          Firewall rules so that only the VPN and DNS are allowed to
                send internet traffic (IE if VPN is down it's offline)
    -r "<network>" CIDR network (IE 192.168.1.0/24)
                required arg: "<network>"
                <network> add a route to (allows replies once the VPN is up)
    -t ""       Configure timezone
                possible arg: "[timezone]" - zoneinfo timezone for container
    -v '<server;user;password>' Configure OpenVPN
                required arg: "<server>;<user>;<password>"
                <server> to connect to
                <user> to authenticate as
                <password> to authenticate with

The 'command' (if provided and valid) will be run instead of openvpn
ENVIRONMENT VARIABLES (only available with docker run)
  • DNS - As above, Use the VPN provider's DNS resolvers
  • ROUTE - As above, add a route to allow replies to your private network
  • TZ - As above, set a zoneinfo timezone, IE EST5EDT
  • VPN - As above, setup a VPN connection

Examples

Any of the commands can be run at creation with docker run or later with docker exec -it openvpn.sh (as of version 1.3 of docker).

Setting the Timezone

sudo cp /path/to/vpn.crt /some/path/vpn-ca.crt
sudo docker run -it --cap-add=NET_ADMIN --device /dev/net/tun --name vpn \
            -v /some/path:/vpn -d dperson/openvpn-client -t EST5EDT \
            -v 'vpn.server.name;username;password'
OR using environment variables
sudo cp /path/to/vpn.crt /some/path/vpn-ca.crt
sudo docker run -it --cap-add=NET_ADMIN --device /dev/net/tun --name vpn \
            -v /some/path:/vpn -e TZ=EST5EDT -d dperson/openvpn \
            -v 'vpn.server.name;username;password'
Will get you the same settings as:
sudo cp /path/to/vpn.crt /some/path/vpn-ca.crt
sudo docker run -it --cap-add=NET_ADMIN --device /dev/net/tun --name vpn \
            -v /some/path:/vpn -d dperson/openvpn-client \
            -v 'vpn.server.name;username;password'
sudo docker exec -it vpn openvpn.sh -t EST5EDT ls -AlF /etc/localtime
sudo docker restart vpn

VPN configuration

In order to work you must provide VPN configuration and the certificate. You can use external storage for /vpn:
sudo docker run -it --cap-add=NET_ADMIN --device /dev/net/tun --name vpn \
            -v /some/path:/vpn -d dperson/openvpn-client \
            -v 'vpn.server.name;username;password'
sudo cp /path/to/vpn.crt /some/path/vpn-ca.crt
sudo docker restart vpn
Or you can store it in the container:
cat /path/to/vpn.crt | sudo docker run -it --cap-add=NET_ADMIN \
            --device /dev/net/tun --name vpn -d dperson/openvpn-client \
            -v 'vpn.server.name;username;password' tee /vpn/vpn-ca.crt \
            >/dev/null
sudo docker restart vpn

Firewall

It's just a simple command line argument (-f) to turn on the firewall, and block all outbound traffic if the VPN is down.
sudo docker run -it --cap-add=NET_ADMIN --device /dev/net/tun --name vpn \
            -v /some/path:/vpn -d dperson/openvpn-client -f \
            -v 'vpn.server.name;username;password'
sudo cp /path/to/vpn.crt /some/path/vpn-ca.crt
sudo docker restart vpn

DNS Issues (May Look Like You Can't Connect To Anything)

Often local DNS and/or your ISP won't be accessable from the new IP address you get from your VPN. You'll need to add the --dns command line option to the docker run statement. Here's an example of doing so, with a Google DNS server:
sudo cp /path/to/vpn.crt /some/path/vpn-ca.crt
sudo docker run -it --cap-add=NET_ADMIN --device /dev/net/tun --name vpn \
            --dns 8.8.4.4 -v /some/path:/vpn -d dperson/openvpn-client \
            -v 'vpn.server.name;username;password'
from https://github.com/dperson/openvpn-client