OpenVPN (Debian) with DPI Evasion

• This is a fork of OpenVPN (Debian) - a secure tunneling daemon.
• This fork contains modifications to OpenVPN that assist with evading detection in DPI censored networks.
• This repository is a direct representation of the openvpn package available from the Ultra Horizon PPA.
• This version of OpenVPN is used within UH VPN Server, available from UH VPN.

Install via apt

sudo add-apt-repository ppa:ultrahorizon/ppa
sudo apt-get update
sudo apt-get install openvpn

Enabling DPI Evasion

• Include the directive uh-xor k within your OpenVPN config file, where k is an even length hex string that will be used as an obfuscation key.
• This directive must be present on the client and server.
• The directive will obfuscate the OpenVPN connection allowing for VPN connectivity in censored networks.
• There is no upper or lower bound set for the length of the XOR key. However, it is advised that one chooses an appropriate length that will provide sufficient entropy for XOR'ing a buffer e.g. 256 bits (64 hex characters) is adequate for obfuscation purposes.
• When the key is shorter than the buffer in length, the XOR operation will applied along the entire buffer modulo the key length to ensure complete coverage.

Build & Install Locally

Ensure the following build tools are installed: autoconf, automake and libtool

Ensure the following library dependencies are met: openssl, libssl-dev, liblz4-1, liblz4-dev, liblzo2-2, liblzo2-dev, libpam0g, libpam0g-dev

Build OpenVPN:

autoreconf -vi
./configure
make
make install

Check Installation:

make check

It is crucial that make check is executed in order to verify that the underlying cryptographic operations of OpenVPN are sound.

Contributions

To make contributions:

1. Fork the repo
2. Make changes to your local repo
3. Create a PR back to the master branch of this repo for review.