The tunio package can be used to redirect I/O from a tun device to a
net.Dialer by using a fork of tun2socks as a library.
This is a work in progress.
Create a CentOS 7 virtual machine:
cat Vagrantfile
# Vagrantfile
Vagrant.configure(2) do |config|
config.vm.box = "chef/centos-7.0"
config.vm.network "private_network", ip: "192.168.88.10"
end
vagrant up
Log in into the newly created virtual machine and install some required packages:
vagrant ssh
sudo yum install -y git gcc glibc-static
# Go
curl https://storage.googleapis.com/golang/go1.5.1.linux-amd64.tar.gz | sudo tar -xzv -C /usr/local/
echo 'export GOROOT=/usr/local/go' >> $HOME/.bashrc
echo 'export PATH=$PATH:$GOROOT/bin' >> $HOME/.bashrc
echo 'export GOPATH=$HOME/go' >> $HOME/.bashrc
source $HOME/.bashrc
Clone the tunio package and switch to the badvpn-lwip branch:
mkdir -p projects
cd projects
git clone https://github.com/getlantern/tunio.git
cd tunio
git checkout badvpn-lwip
go get -d -t .
Compile tun2io's libraries:
make lib
# ...
# cc -shared -o lib/libtun2io.so tun2io.o ./obj/*.o -lrt -lpthread
# ar rcs lib/libtun2io.a tun2io.o ./obj/*.o
Create a new tun device, let's name it tun0.
#!/bin/bash
DEVICE_NAME=tun0
DEVICE_IP=10.0.0.1
sudo ip tuntap del $DEVICE_NAME mode tun
sudo ip tuntap add $DEVICE_NAME mode tun
sudo ifconfig $DEVICE_NAME $DEVICE_IP netmask 255.255.255.0
Replace the vm's name servers with 8.8.8.8 and 8.8.4.4.
echo "nameserver 8.8.8.8" | sudo tee /etc/resolv.conf
echo "nameserver 8.8.4.4" | sudo tee -a /etc/resolv.conf
The easiest way to try the net.Dialer is by creating a transparent tunnel
with an external host, in this example we are going to use the vm's host as
external host.
Modify the routing table to allow direct traffic with the name servers and with the external host.
#!/bin/bash
HOST_IP=10.0.0.105
ORIGINAL_GW=10.0.2.2
sudo route add 8.8.8.8 gw $ORIGINAL_GW metric 5
sudo route add 8.8.4.4 gw $ORIGINAL_GW metric 5
sudo route add $HOST_IP gw $ORIGINAL_GW metric 5
sudo route add default gw 10.0.0.2 metric 6
Any other package will pass through 10.0.0.2 (our tun0 device).
After altering the routing table, you should not be able to ping external hosts:
ping google.com
PING google.com (74.125.227.165) 56(84) bytes of data.
^C
--- google.com ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 4001ms
But you should be able to ping the nameservers and $HOST_IP, because they're
using the original router.
ping $HOST_IP
PING 10.0.0.105 (10.0.0.105) 56(84) bytes of data.
64 bytes from 10.0.0.105: icmp_seq=1 ttl=63 time=3.45 ms
64 bytes from 10.0.0.105: icmp_seq=2 ttl=63 time=0.403 ms
^C
--- 10.0.0.105 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.403/1.928/3.454/1.526 ms
Install socat in your host and open a transparent TCP tunnel from port
20443 to google.com:443.
brew install socat
socat TCP-LISTEN:20443,fork TCP:www.google.com:443
Now you should be able to run the test!
go test
# ...
# PASS
# ok _/home/vagrant/projects/tunio 1.260s
We used a transparent proxy for this test, but you are not bound to transparent
proxies only, it depends on the net.Conn returned by the net.Dialer. You
can also use socat to create a tcp-to-socks tunnel to simulate a net.Conn
over SOCKS:
# terminal 1
socat TCP-LISTEN:20443,fork socks:127.0.0.1:www.google.com:443,socksport=9999
# terminal 2
ssh -D 9999 remote@example.org
and a net.Conn over Lantern:
# terminal 1
socat TCP-LISTEN:20443,fork PROXY:127.0.0.1:www.google.com:443,proxyport=8787
# termina 2
lantern -role client -addr :8787