docker-vpnc

A Dockerfile based off of phusion/baseimage-docker that establishes a VPN connection with vpnc.

Environment Variables

• VPNC_GATEWAY: IP/name of your IPSec gateway
• VPNC_ID: Group name
• VPNC_SECRET: Group password
• VPNC_USERNAME: XAUTH username
• VPNC_PASSWORD: XAUTH password

Usage

First, ensure that all of the environment variables above exist in a file:

$ cat > .env <<EOF
VPNC_GATEWAY=1.2.3.4
VPNC_ID=joker-group
VPNC_SECRET=joker-secret
VPNC_USERNAME=joker
VPNC_PASSWORD=joker-password
EOF

Note: You can also use the -e option to docker run.

Next, build the container:

$ docker build -t azavea/vpnc .

Lastly, run the container, and then ask ipify what your external IP address is. It should return the IP address of your VPN endpoint.

$ docker run --rm -ti --privileged --env-file .env --dns 8.8.8.8 \
    azavea/vpnc /sbin/my_init --quiet -- \
    /bin/sh -c "sleep 5 && curl 'https://api.ipify.org?format=json'"
VPNC started in foreground...
{"ip":"216.158.51.82"}
$ curl 'https://api.ipify.org?format=json'
{"ip":"52.2.53.130"}

Option Explanations

• --rm: Removes the container after it's done executing
• --privileged: Allows the container to create and make use of the tun device
• --env-file: Loads up the contents of .env into the container's environment
• --dns: Make use of Google's DNS servers for name resolution within the container
• /sbin/my_init: The init system provided by phusion/baseimage-docker

Everything after -- is the command we want to run within the container, in addition to the services managed by my_init.

Note: If you get an error like the one below, it is a known bug with vpnc:

select: Interrupted system call
terminated by signal: 15