This library provides a simplified Swift/Obj-C implementation of the OpenVPN® protocol for the Apple platforms. The crypto layer is built on top of OpenSSL 1.1.0i, which in turn enables support for a certain range of encryption and digest algorithms.
The client is known to work with OpenVPN® 2.3+ servers.
- [x] Handshake and tunneling over UDP or TCP
- [x] Ciphers
- AES-CBC (128/192/256 bit)
- AES-GCM (128/192/256 bit, 2.4)
- [x] HMAC digests
- SHA-2 (224/256/384/512 bit)
- [x] NCP (Negotiable Crypto Parameters, 2.4)
- [x] TLS handshake
- Server validation (CA, EKU)
- Client certificate
- [x] TLS wrapping
- Authentication (
- Encryption (
- Authentication (
- [x] Compression framing
--comp-lzo(deprecated in 2.4)
- [x] Compression algorithms
- LZO (via
- LZO (via
- [x] Key renegotiation
- [x] Replay protection (hardcoded window)
The library therefore supports compression framing, just not newer compression. Remember to match server-side compression and framing, otherwise the client will shut down with an error. E.g. if server has
comp-lzo no, client must use
compressionFraming = .compLZO.
Support for .ovpn configuration
TunnelKit can parse .ovpn configuration files. Below are a few limitations worth mentioning.
- UDP fragmentation, i.e.
- Compression via
--compressother than empty or
- External file references (inline
- Encrypted client certificate keys
- MTU overrides
hostvalues (first wins)
--redirect-gateway, VPN is always default gateway (no split tunnelling yet)
Many other flags are ignored too but it's normally not an issue.
- iOS 11.0+ / macOS 10.11+
- Xcode 10+ (Swift 4.2)
- Git (preinstalled with Xcode Command Line Tools)
- Ruby (preinstalled with macOS)
- CocoaPods 1.6.0
- jazzy (optional, for documentation)
- Disable Bitcode
It's highly recommended to use the Git and Ruby packages provided by Homebrew.
To use with CocoaPods just add this to your Podfile:
Download the library codebase locally:
$ git clone https://github.com/keeshux/tunnelkit.git
Assuming you have a working CocoaPods environment, setting up the library workspace only requires installing the pod dependencies:
$ pod install
After that, open
TunnelKit.xcworkspace in Xcode and run the unit tests found in the
TunnelKitTests target. A simple CMD+U while on
TunnelKit-iOS should do that as well.
There is a
Demo directory containing a simple app for testing the tunnel, called
BasicTunnel. As usual, prepare for CocoaPods:
$ pod install
Demo.xcworkspace and run the
For the VPN to work properly, the
BasicTunnel demo requires:
- App Groups and Keychain Sharing capabilities
- App IDs with Packet Tunnel entitlements
both in the main app and the tunnel extension target.
In order to test connection to your own server, modify the file
Demo/BasicTunnel-[iOS|macOS]/ViewController.swift and make sure to set
ca to the PEM encoded certificate of your VPN server's CA.
private let ca = CryptoContainer(pem: """ -----BEGIN CERTIFICATE----- MIIFJDCC... -----END CERTIFICATE----- """)
The library is split into two modules, in order to decouple the low-level protocol implementation from the platform-specific bridging, namely the NetworkExtension VPN framework.
Full documentation of the public interface is available and can be generated with jazzy. After installing the jazzy Ruby gem with:
$ gem install jazzy
enter the root directory of the repository and run:
The generated output is stored into the
docs directory in HTML format.
Here you will find the low-level entities on top of which the connection is established. Code is mixed Swift and Obj-C, most of it is not exposed to consumers. The Core module depends on OpenSSL and is mostly platform-agnostic.
The entry point is the
SessionProxy class. The networking layer is fully abstract and delegated externally with the use of opaque
The goal of this module is packaging up a black box implementation of a NEPacketTunnelProvider, which is the essential part of a Packet Tunnel Provider app extension. You will find the main implementation in the
Due to the restrictive license (GPLv2), LZO support is provided as an optional subspec.
This project is licensed under the GPLv3.
As seen in libsignal-protocol-c:
Additional Permissions For Submission to Apple App Store: Provided that you are otherwise in compliance with the GPLv3 for each covered work you convey (including without limitation making the Corresponding Source available in compliance with Section 6 of the GPLv3), the Author also grants you the additional permission to convey through the Apple App Store non-source executable versions of the Program as incorporated into each applicable covered work as Executable Versions only under the Mozilla Public License version 2.0 (https://www.mozilla.org/en-US/MPL/2.0/).
Part I and II do not apply to the LZO library, which remains licensed under the terms of the GPLv2+.
By contributing to this project you are agreeing to the terms stated in the Contributor License Agreement (CLA).
For more details please see CONTRIBUTING.
- PIATunnel - Copyright (c) 2018-Present Private Internet Access
- SwiftyBeaver - Copyright (c) 2015 Sebastian Kreutzberger
- lzo - Copyright (c) 1996 - 2017 Markus F.X.J. Oberhumer
This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit. (https://www.openssl.org/)
© 2002-2018 OpenVPN Inc. - OpenVPN is a registered trademark of OpenVPN Inc.