This is a docker image with simple VPN (PPTP) server.
This container will write a /etc/ppp/chap-secrets file based on the following env variables which must be set: $client $server $secret $acceptable_local_ip_addresses
To start VPN server as a docker container run:
docker run -ti --net=host --privileged -p 1723:1723 -e client=some_user -e server=* -e password=password -e acceptable_local_ip_addresses=* mmontagna/docker-vpn-pptp