Secure Host-to-Host VPN

What is it?

This is a secure host-to-host communication between a client and a server (client on one instance of a Linux virtual machine and server on another instance). This repository relies heavily on openSSL for a secure connection. It uses AES for confidentiality and HMAC for Integrity of the message packets. These programs also use the TUN interface to establish a connection.

Currently this VPN only works for Linux.

Setting up the VPN between the two virtual machines

Open two virtual machines and copy the repository into both virtual machines.

A makefile is provided for compiling the the client and server program.

Go to the directory on both VMs and initiate the makefile with

$ make

Next, you need to establish the tunnel interface between the VMs

On the server virtual machine:

$ sudo ./serv

Now you will need to establish the tunnel (tun) interface for the server.

On another terminal run these commands

$ sudo ip addr add 10.0.4.1/24 dev tun0
$ sudo ifconfig tun0 up

Now the server VM has an two interfaces, one is its own Ethernet card interface, and the other is the virtual network interface called tun0.

Lastly do a ifconfig to get the ip address for the server (need to pass it to the client).

$ ifconfig

On the client virtual machine:

$ sudo ./cli "ip address of the server"

Now you will need to establish the tunnel (tun) interface for the client.

On another terminal run these commands

$ sudo ip addr add 10.0.5.1/24 dev tun0
$ sudo ifconfig tun0 up

Now the client VM has an two interfaces, one is its own Ethernet card interface, and the other is the virtual network interface called tun0.

Lastly, route the virtual machines to each other

Server's virtual machine

$ sudo route add -net 10.0.5.0 netmask 255.255.255.0 dev tun0

Client's virtual machine

$ sudo route add -net 10.0.4.0 netmask 255.255.255.0 dev tun0

Communicating between virtual machines

Now you can ping and ssh from one virtual machine to another machine.

On server you can try:

$ ping 10.0.5.1
$ ssh 10.0.5.1

On client you can try:

$ ping 10.0.4.1
$ ssh 10.0.4.1

Special characters for client side of the VPN

Also there is 3 special characters that you can enter into the client program.

• q: Quits the session.
• k: Change the key between server and client.
• v: Change the IV between the server and client.

Demo

Link: https://www.youtube.com/watch?v=mr7EfV9hIn0

Author

Ardlan Khalili

Questions?

Email me at ardlankhalili@gmail.com