IPsec VPN Server on Docker

Docker image to run an IPsec VPN server, with both IPsec/L2TP and IPsec/XAuth ("Cisco IPsec").

Based on Debian Jessie with Libreswan (IPsec VPN software) and xl2tpd (L2TP daemon).

Read this in other languages: English, Chinese.

Install Docker

Follow these instructions to get Docker running on your server.

Download

Get the trusted build from the Docker Hub registry:

docker pull hwdsl2/ipsec-vpn-server

Alternatively, you may build from source code on GitHub.

How to use this image

Environment variables

This Docker image uses the following three environment variables, that can be declared in an env file:

VPN_IPSEC_PSK=<IPsec pre-shared key>
VPN_USER=<VPN Username>
VPN_PASSWORD=<VPN Password>

This will create a single user account for VPN login. The IPsec PSK (pre-shared key) is specified by the VPN_IPSEC_PSK environment variable. The VPN username is defined in VPN_USER, and VPN password is specified by VPN_PASSWORD.

Note 1: In your env file, DO NOT put single or double quotes around values, or add space around =. Also, DO NOT use these characters within values: \ " '

Note 2: The same VPN account can be used by your multiple devices. However, due to a limitation of the IPsec protocol, if these devices are behind the same NAT (e.g. home router), they cannot simultaneously connect to the VPN server.

All the variables to this image are optional, which means you don't have to type in any environment variable, and you can have an IPsec VPN server out of the box! Read the sections below for details.

Start the IPsec VPN server

(IMPORTANT) First, run this command on the Docker host to load the IPsec NETKEY kernel module:

sudo modprobe af_key

Start a new Docker container with the following command (replace ./vpn.env with your own env file) :

docker run \
    --name ipsec-vpn-server \
    --env-file ./vpn.env \
    -p 500:500/udp \
    -p 4500:4500/udp \
    -v /lib/modules:/lib/modules:ro \
    -d --privileged \
    --restart=always \
    hwdsl2/ipsec-vpn-server

Retrieve VPN login details

If you did not set environment variables via an env file, VPN_USER will default to vpnuser and both VPN_IPSEC_PSK and VPN_PASSWORD will be randomly generated. To retrieve them, show the logs of the running container:

docker logs ipsec-vpn-server

Search for these lines in the output:

Connect to your new VPN with these details:

Server IP: <VPN Server IP>
IPsec PSK: <IPsec pre-shared key>
Username: <VPN Username>
Password: <VPN Password>

Check server status

To check the status of your IPsec VPN server, you can pass ipsec status to your container like this:

docker exec -it ipsec-vpn-server ipsec status

Next steps

Get your computer or device to use the VPN. Please refer to:

Configure IPsec/L2TP VPN Clients
Configure IPsec/XAuth ("Cisco IPsec") VPN Clients

If you get an error when trying to connect, see Troubleshooting.

Enjoy your very own VPN!

Technical details

There are two services running: Libreswan (pluto) for the IPsec VPN, and xl2tpd for L2TP support.

Clients are configured to use Google Public DNS when the VPN connection is active.

The default IPsec configuration supports:

IKEv1 with PSK and XAuth ("Cisco IPsec")
IPsec/L2TP with PSK

The ports that are exposed for this container to work are:

4500/udp and 500/udp for IPsec

Build from source code

Advanced users can download and compile the source yourself from GitHub:

git clone https://github.com/hwdsl2/docker-ipsec-vpn-server.git
cd docker-ipsec-vpn-server
docker build -t hwdsl2/ipsec-vpn-server .

or use this if not modifying the source code:

docker build -t hwdsl2/ipsec-vpn-server github.com/hwdsl2/docker-ipsec-vpn-server.git

Author

Lin Song (linsongui@gmail.com)

Final year U.S. PhD candidate, majoring in Electrical and Computer Engineering (ECE)
Actively seeking opportunities in areas such as Software or Systems Engineering
Contact me on LinkedIn: https://www.linkedin.com/in/linsongui

Thanks to all contributors to this project!

License

This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License
Attribution required: please include my name in any derivative and let me know how you have improved it!

thanq/docker-ipsec-vpn-server