OpenVPN Forwarder

Forward OpenVPN traffic to Mysterium Network nodes

Quickstart

Build and run the service via go run ci/mage.go build run

Redirect Openvpn's traffic (from the host machine)

Let's assume:

• You are SSH'ed to server
• You run OpenVPN server on host machine here

1. Run forwarder as a Docker container:

docker run -d --restart=always --name forwarder --network host --cap-add NET_ADMIN mysteriumnetwork/openvpn-forwarder \
    --proxy.bind=0.0.0.0:8443 \
    --proxy.allow=0.0.0.0/0 \
    --proxy.upstream-url="https://superproxy1.com:8443" \
    --filter.hostnames="ipinfo.io" \
    --proxy.upstream-url="http://superproxy2.com:8080" \
    --filter.zones="ipify.org"

2. Redirect HTTP ports to forwarder:

iptables -t nat -A PREROUTING -p tcp -m multiport --dports 80,443 -j REDIRECT --to-ports 8443

3. Forwarder redirects HTTP traffic to upstream HTTPS proxy (this case just hostname 'ipinfo.io'):

sudo openvpn --config client.ovpn
curl "http://ipinfo.io/"
curl "https://ipinfo.io/"

Redirect OpenVPN's traffic (from Docker container)

Let's assume:

• You are SSH'ed to server
• You run OpenVPN server inside Docker container named 'openvpn'
• Your OpenVPN container is assigned to Docker network 'openvpn_network'

1. Run forwarder as a Docker container:

docker run -d --restart=always --name forwarder --network openvpn_network --cap-add NET_ADMIN mysteriumnetwork/openvpn-forwarder \
    --proxy.upstream-url="https://superproxy.com:443" \
    --filter.hostnames="ipinfo.io,whatismyipaddress.com"

2. Find what IP forwarder was assigned:

FORWARDER_IP=`docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' forwarder`

3. Redirect HTTP ports to forwarder (from Docker container):

docker exec -it openvpn iptables -t nat -A PREROUTING -p tcp -m multiport --dports 80,443 -j DNAT --to-destination $FORWARDER_IP:8443

4. Forwarder redirects HTTP traffic to upstream HTTPS proxy (this case just 2 hostnames):

sudo openvpn --config client.ovpn
curl "http://ipinfo.io/"
curl "https://ipinfo.io/"

User session stickiness

To enable user stickiness the following configuration is required from the OpenVPN server:

Add the following line to the /etc/openvpn/openvpn.conf file:

learn-address /etc/openvpn/stick-user.sh

And create the file /etc/openvpn/stick-user.sh file:

#!/bin/bash
if [[ "$1" == "add" || "$1" == "update" ]]; then
	userHash=$(echo $3 | sha256sum | cut -d' ' -f1)
	curl -i -X POST http://forwarder:8000/api/v1/map -H "Accept: application/json" -H "Content-Type: application/json" -d "{\"ip\":\"$2\",\"userId\":\"$userHash\"}"
fi

#!/bin/bash
if [[ "$1" == "add" || "$1" == "update" ]]; then
    userHash=$(echo $3 | sha256sum | cut -d' ' -f1)
    wget -q -O - --header="Accept: application/json" --header="Content-Type: application/json" --post-data="{\"ip\":\"$2\",\"userId\":\"$userHash\"}" http://forwarder:8000/api/v1/map
fi

This will send an update to forwarder with virtual IP to UserHash mapping on every user connection.

To be able to get user's virtual IP for mapping we need to disable MASQUERADE to the forwarder container:

Execute the following command on the openvpn container:

docker exec -it openvpn iptables -t nat -A POSTROUTING ! -d forwarder -j MASQUERADE

And the forwarder container should be started with the following environment variables:

docker run -d --restart=always --name forwarder --network openvpn_network -e "EXTRA_ROUTES=192.168.255.0/24:openvpn" \
    --cap-add NET_ADMIN mysteriumnetwork/openvpn-forwarder \
    --proxy.upstream-url="https://superproxy.com:443" \
    --filter.hostnames="ipinfo.io,whatismyipaddress.com"

• 192.168.255.0/24 - is a OpenVPN subnet that will be used for virtual IPs of clients;
• forwarder - is a container name of the OpenVPN-forwarder, this name should resolve from any container in the openvpn_network docker network.
• openvpn - is a container name of the OpenVPN server, this name should resolve from any container in the openvpn_network docker network.

Note: EXTRA_ROUTES environment varialbe can contain multiple comma separated routes:

-e "EXTRA_ROUTES=192.168.255.0/24:openvpn,192.168.254.0/24:172.16.1.1"

The 192.168.254.0/24:172.16.1.1 pair represent destination subnet and gateway that will be used for it.

Debugging of traffic

1. Check your server's current IP

curl "http://ipinfo.io/"

2. Check if your upstream HTTPS proxy is accepting requests

curl --proxytunnel --proxy superproxy.com:8080 "http://ipinfo.io/"

You are supposed to see your server's IP changed

3. Check if forwarder is redirecting requests to upstream HTTPS proxy

FORWARDER_IP=`docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' forwarder`
curl --proxy $FORWARDER_IP:8443 "http://ipinfo.io"

You should see different current IP of your server

4. Check if traffic of Openvpn's container is being forwarded

docker exec -it openvpn curl "https://ipinfo.io/"
OR
docker exec -it openvpn wget -q -O - "https://ipinfo.io/"

Metrics of traffic

After your bind API with e.g. `--proxy.api-bind=127.0.0.1:8000```, Prometheus metrics are available on http://127.0.0.1:8000/metrics:

• proxy_request_data - Proxy request data in bytes (Counter);
• proxy_request_duration - Proxy request duration in seconds (Histogram);
• proxy_number_of_live_connections - Number of currently live connections (Gauge);
• proxy_number_of_processed_connections - Number of incoming connections which were successfully assigned and processed (Counter);

Forward non-standard ports to OpenVPN forwarder

By default, OpenVPN forwarder listen ':8443' port and sends traffic to the standard port only

• :80 for HTTP traffic
• :443 for HTTPS traffic

If you need to forward non standard port too, the following steps required:

1. Start OpenVPN forwarder with the --proxy.port-map flag:

docker run -d --restart=always --name forwarder --network host --cap-add NET_ADMIN mysteriumnetwork/openvpn-forwarder \
    --proxy.bind=0.0.0.0:8443 \
    --proxy.allow=0.0.0.0/0 \
    --proxy.upstream-url="https://superproxy.com:443" \
    --proxy.port-map=18443:8443,1234:1234

2. Apply additional iptables rule to forward required traffic:

docker exec -it openvpn iptables -t nat -A PREROUTING -p tcp -m tcp --dport 8443 -j DNAT --to-destination 127.0.0.1:18443
docker exec -it openvpn iptables -t nat -A PREROUTING -p tcp -m tcp --dport 1234 -j DNAT --to-destination 127.0.0.1:1234

This will allow keeping the original non-standard port.

License

This project is licensed under the terms of the GNU General Public License v3.0 (see details).