250 lines
10 KiB
Markdown
250 lines
10 KiB
Markdown
|
|
|
|
[](LICENSE)
|
|
|
|
# TunnelKit
|
|
|
|
This library provides a generic framework for VPN development and a simplified Swift/Obj-C implementation of the OpenVPN® protocol for the Apple platforms. The crypto layer is built on top of [OpenSSL 1.1.1][dep-openssl], which in turn enables support for a certain range of encryption and digest algorithms.
|
|
|
|
## Getting started
|
|
|
|
The client is known to work with [OpenVPN®][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-1
|
|
- SHA-2 (224/256/384/512 bit)
|
|
- [x] NCP (Negotiable Crypto Parameters, 2.4)
|
|
- Server-side
|
|
- [x] TLS handshake
|
|
- Server validation (CA, EKU)
|
|
- Client certificate
|
|
- [x] TLS wrapping
|
|
- Authentication (`--tls-auth`)
|
|
- Encryption (`--tls-crypt`)
|
|
- [x] Compression framing
|
|
- Via `--comp-lzo` (deprecated in 2.4)
|
|
- Via `--compress`
|
|
- [x] Compression algorithms
|
|
- LZO (via `--comp-lzo` or `--compress lzo`)
|
|
- [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 details worth mentioning.
|
|
|
|
#### Non-standard
|
|
|
|
- Single-byte XOR masking
|
|
- Via `--scramble xormask <character>`
|
|
- XOR all incoming and outgoing bytes by the ASCII value of the character argument
|
|
- See [Tunnelblick website][about-tunnelblick-xor] for more details
|
|
|
|
#### Unsupported
|
|
|
|
- UDP fragmentation, i.e. `--fragment`
|
|
- Compression via `--compress` other than empty or `lzo`
|
|
- Connecting via proxy
|
|
- External file references (inline `<block>` only)
|
|
- Static key encryption (non-TLS)
|
|
- `<connection>` blocks
|
|
- `vpn_gateway` and `net_gateway` literals in routes
|
|
|
|
#### Ignored
|
|
|
|
- Some MTU overrides
|
|
- `--link-mtu` and variants
|
|
- `--mssfix`
|
|
- Multiple `--remote` with different `host` values (first wins)
|
|
- Static client-side routes
|
|
|
|
Many other flags are ignored too but it's normally not an issue.
|
|
|
|
## Installation
|
|
|
|
### Requirements
|
|
|
|
- iOS 11.0+ / macOS 10.15+
|
|
- SwiftPM 5.3
|
|
- Git (preinstalled with Xcode Command Line Tools)
|
|
|
|
It's highly recommended to use the Git package provided by [Homebrew][dep-brew].
|
|
|
|
### Caveats
|
|
|
|
Make sure to disable Bitcode in "Release" targets (iOS), otherwise the library [would not be able to link OpenSSL][about-pr-bitcode].
|
|
|
|
Recent versions of Xcode (latest is 13.1) have an issue where the "Frameworks" directory is replicated inside application extensions. This is not a blocker during development, but will prevent your archive from being validated against App Store Connect due to the following error:
|
|
|
|
ERROR ITMS-90206: "Invalid Bundle. The bundle at '*.appex' contains disallowed file 'Frameworks'."
|
|
|
|
You will need to add a "Run Script" phase to your main app target where you manually remove the offending folder, i.e.:
|
|
|
|
rm -rf "${BUILT_PRODUCTS_DIR}/${PLUGINS_FOLDER_PATH}/YourTunnelTarget.appex/Frameworks"
|
|
|
|
for iOS and:
|
|
|
|
rm -rf "${BUILT_PRODUCTS_DIR}/${PLUGINS_FOLDER_PATH}/YourTunnelTarget.appex/Contents/Frameworks"
|
|
|
|
for macOS.
|
|
|
|
### Demo
|
|
|
|
Download the library codebase locally:
|
|
|
|
$ git clone https://github.com/passepartoutvpn/tunnelkit.git
|
|
|
|
There are demo targets containing a simple app for testing the tunnel, called `BasicTunnel`. Open `Demo/TunnelKit.xcodeproject` in Xcode and run it on both iOS and macOS.
|
|
|
|
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 connectivity in your own environment, modify the file `Demo/Demo/Configuration.swift` to match your VPN server parameters.
|
|
|
|
Example:
|
|
|
|
private let ca = CryptoContainer(pem: """
|
|
-----BEGIN CERTIFICATE-----
|
|
MIIFJDCC...
|
|
-----END CERTIFICATE-----
|
|
""")
|
|
|
|
Make sure to also update the following constants in the same files, according to your developer account and your target bundle identifiers:
|
|
|
|
public static let appGroup
|
|
public static let tunnelIdentifier
|
|
|
|
Remember that the App Group on macOS requires a team ID prefix.
|
|
|
|
## Documentation
|
|
|
|
The library is split into several modules, in order to decouple the low-level protocol implementation from the platform-specific bridging, namely the [NetworkExtension][ne-home] VPN framework.
|
|
|
|
Full documentation of the public interface is available and can be generated by opening the package in Xcode and running "Build Documentation" (Xcode 13).
|
|
|
|
### TunnelKitCore
|
|
|
|
Contains the building blocks of a VPN protocol. Eventually, a consumer would implement the `Session` interface, expected to start and control the VPN session. A session is expected to work with generic network interfaces:
|
|
|
|
- `LinkInterface` (e.g. a socket)
|
|
- `TunnelInterface` (e.g. an `utun` interface)
|
|
|
|
There are no physical network implementations (e.g. UDP or TCP) in this module.
|
|
|
|
### TunnelKitManager
|
|
|
|
This component includes convenient classes to control the VPN tunnel from your app without the NetworkExtension headaches. Have a look at `VPNProvider` implementations:
|
|
|
|
- `MockVPNProvider` (default, useful to test on simulator)
|
|
- `NetworkExtensionVPNProvider` (anything based on NetworkExtension)
|
|
|
|
### TunnelKitAppExtension
|
|
|
|
Provides a layer on top of the NetworkExtension framework. Most importantly, bridges native [NWUDPSession][ne-udp] and [NWTCPConnection][ne-tcp] to an abstract `GenericSocket` interface, thus making a multi-protocol VPN dramatically easier to manage.
|
|
|
|
### TunnelKitIKE
|
|
|
|
Here you find `NativeProvider`, a generic way to manage a VPN profile based on the native IPSec/IKEv2 protocols. Just wrap a `NEVPNProtocolIPSec` or `NEVPNProtocolIKEv2` object in a `NetworkExtensionVPNConfiguration` and use it to install or connect to the VPN.
|
|
|
|
### TunnelKitOpenVPN*
|
|
|
|
#### Protocol
|
|
|
|
Here are the low-level entities on top of which an OpenVPN connection is established. Code is mixed Swift and Obj-C, most of it is not exposed to consumers. The protocol implementation in particular depends on OpenSSL.
|
|
|
|
The entry point is the `OpenVPNSession` class. The networking layer is fully abstract and delegated externally with the use of opaque `IOInterface` (`LinkInterface` and `TunnelInterface`) and `OpenVPNSessionDelegate` protocols.
|
|
|
|
#### AppExtension
|
|
|
|
Another goal of this area is packaging up a black box implementation of a [NEPacketTunnelProvider][ne-ptp], which is the essential part of a Packet Tunnel Provider app extension. You will find the main implementation in the `OpenVPNTunnelProvider` class.
|
|
|
|
A debug log snapshot is optionally maintained and shared by the tunnel provider to host apps via the App Group container.
|
|
|
|
#### Manager
|
|
|
|
On the client side, you manage the VPN profile with the `OpenVPNProvider` class, which is a specific implementation of `NetworkExtensionVPNProvider`.
|
|
|
|
### TunnelKitLZO
|
|
|
|
Due to the restrictive license (GPLv2), LZO support is provided as an optional component.
|
|
|
|
## License
|
|
|
|
Copyright (c) 2021 Davide De Rosa. All rights reserved.
|
|
|
|
### Part I
|
|
|
|
This project is licensed under the [GPLv3][license-content].
|
|
|
|
### Part II
|
|
|
|
As seen in [libsignal-protocol-c][license-signal]:
|
|
|
|
> 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 III
|
|
|
|
Part I and II do not apply to the LZO library, which remains licensed under the terms of the GPLv2+.
|
|
|
|
### Contributing
|
|
|
|
By contributing to this project you are agreeing to the terms stated in the [Contributor License Agreement (CLA)][contrib-cla].
|
|
|
|
For more details please see [CONTRIBUTING][contrib-readme].
|
|
|
|
## Credits
|
|
|
|
- [lzo][dep-lzo-website] - Copyright (c) 1996-2017 Markus F.X.J. Oberhumer
|
|
- [PIATunnel][dep-piatunnel-repo] - Copyright (c) 2018-Present Private Internet Access
|
|
- [SURFnet][ppl-surfnet]
|
|
- [SwiftyBeaver][dep-swiftybeaver-repo] - Copyright (c) 2015 Sebastian Kreutzberger
|
|
- [XMB5][ppl-xmb5] for the [XOR patch][ppl-xmb5-xor] - Copyright (c) 2020 Sam Foxman
|
|
|
|
This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit. ([https://www.openssl.org/][dep-openssl])
|
|
|
|
Copyright (c) 2002-2018 OpenVPN Inc. - OpenVPN is a registered trademark of OpenVPN Inc.
|
|
|
|
## Contacts
|
|
|
|
Twitter: [@keeshux][about-twitter]
|
|
|
|
Website: [passepartoutvpn.app][about-website]
|
|
|
|
[openvpn]: https://openvpn.net/index.php/open-source/overview.html
|
|
|
|
[dep-brew]: https://brew.sh/
|
|
[dep-openssl]: https://www.openssl.org/
|
|
|
|
[ne-home]: https://developer.apple.com/documentation/networkextension
|
|
[ne-ptp]: https://developer.apple.com/documentation/networkextension/nepackettunnelprovider
|
|
[ne-udp]: https://developer.apple.com/documentation/networkextension/nwudpsession
|
|
[ne-tcp]: https://developer.apple.com/documentation/networkextension/nwtcpconnection
|
|
|
|
[license-content]: LICENSE
|
|
[license-signal]: https://github.com/signalapp/libsignal-protocol-c#license
|
|
[license-mit]: https://choosealicense.com/licenses/mit/
|
|
[contrib-cla]: CLA.rst
|
|
[contrib-readme]: CONTRIBUTING.md
|
|
|
|
[dep-piatunnel-repo]: https://github.com/pia-foss/tunnel-apple
|
|
[dep-swiftybeaver-repo]: https://github.com/SwiftyBeaver/SwiftyBeaver
|
|
[dep-lzo-website]: http://www.oberhumer.com/opensource/lzo/
|
|
[ppl-surfnet]: https://www.surf.nl/en/about-surf/subsidiaries/surfnet
|
|
[ppl-xmb5]: https://github.com/XMB5
|
|
[ppl-xmb5-xor]: https://github.com/passepartoutvpn/tunnelkit/pull/170
|
|
[about-tunnelblick-xor]: https://tunnelblick.net/cOpenvpn_xorpatch.html
|
|
[about-pr-bitcode]: https://github.com/passepartoutvpn/tunnelkit/issues/51
|
|
|
|
[about-twitter]: https://twitter.com/keeshux
|
|
[about-website]: https://passepartoutvpn.app
|