---------------------------------------- -----------------------------------------
|10.10.10.14 | |10.10.10.15 |
| | | |
| | | |
| ip route 172.0.0.0/8 --- | | ----------------------------------- |
| | | | | test-dev(172.0.0.1/24) | |
| \|/ | | ----------------------------------- |
| ---------------------------------- | | ----------------------------------- |
| | tun0(192.168.0.1->192.168.0.2)| | | | tun0(192.168.0.2->192.168.0.1) | |
| ---------------------------------- | | ----------------------------------- |
| /|\ | | | | /|\ |
| write| |read | | read| |write |
| | \|/ | UDP | \|/ | |
| xtun <--------------------------------------------------------------------> xtun |
| | | |
---------------------------------------- -----------------------------------------
Having 2 nodes with ip 10.10.10.14 and 10.10.10.15. On each node we run an xtun which creates a tun device named tun0. Then we configure tun0 on 10.10.10.14 with ip 192.168.0.1 and destination 192.168.0.2, and on 10.10.10.15 with ip 192.168.0.2 and destination 192.168.0.1. Now, we have created 2 point to point interface on 2 nodes, xtun will read all data flow from tun0 and forward to the other node with UDP tunnel, on reading data flow from UDP tunnel, the other node would write raw data to tun0 too. Then, all following data flow will be controled by the kernel protocol stack.
In order to demonstrate a complete VPN(Virtual private network) situation, we create a test-dev interface on 10.10.10.15 with ip 172.0.0.1/24. On 10.10.10.14 we route all trafic with destination to 172.0.0.0/8 to tun0.
Then what it is? You can visit 172.0.0.1 on 10.10.10.14 just like you are in the same private network with 172.0.0.1.
- On
10.10.10.14
## Launch a `xtun`
./xtun tun0 10.10.10.15
## Configure tun0
ifconfig tun0 192.168.0.1 pointopoint 192.168.0.2 mtu 1500
## Route trafic to tun0
ip route add 172.0.0.0/8 via 192.168.0.1
- On
10.10.10.15
## Luanch a `xtun`
./xtun tun0 10.10.10.14
## Configure tun0
ifconfig tun0 192.168.0.2 pointopoint 192.168.0.1 mtu 1500
## Add link and configure as 172.0.0.1/24
ip link add test-dev type bridge
ifconfig test-dev 172.0.0.1 netmask 255.255.255.0
- Test with
nc
On 10.10.10.15
nc -l 172.0.0.1 80
On 10.10.10.15
nc 172.0.0.1 80