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Previous Students projcets

See Student_projects for completed student projects (sponsored by GSoC 2017 and others)

Google Summer of Code Ideas Page

While IKE and IPsec have been around for almost 20 years, like SSL/TLS, the protocols are still evolving and getting new features to deal with an ever changing world. The Libreswan Project's core developers have come up with a list of projects that they believe would be interesting for students to work on. The mentors have a personal interest in these projects as well. If any of these projects look interesting to you, feel free to contact the developers either on the developer mailinglist or the #swan channel on the FreeNode IRC network. You can also email with any questions you have or if you would like to introduce yourself.

A quick overview and history of The Libreswan Project was presented by Paul Wouters as part of the Opportunistic IPsec presentation at the 2016 [Linux Security Summit]. There is also a Video Recording of the presentation.

Re-implement the KVM/python based testing infrastructure

Required Skills: General DevOps and Virtualization skills, python and shell scripting

Libreswan Mentors: Andrew Cagney, Paul Wouters

The goal is to investigate using another container technology that is better suited for our use. This could be raw namespaces, "unshare", kubernetes, docker (without systemd), openshift, openstack or something else. Note that since it needs to support containerized IPsec kernel stacks, LXC or vserver will not work.

The following new properties are desired for the new test harness:

  • Allow most tests to run with containers running libreswan, instead of VMs running libreswan
  • It should be able to run many tests in parallel on 1 machine
  • It should be able to spread jobs on multiple machines
  • Distinguish minor issues (diff in output) from major issues (different number of IKE or IPsec SA's)
  • Be as independent from the host OS as possible
  • Keep similar web based reporting output

The following properties of the current test harness should not be lost:

The libreswan testing infrastructure has its roots in the ancient UserModeLinux (UML). It ran for a number of years until UML stopped working reliably on newer kernels. In 2012 this system was migrated to the current system which us based on KVM, QEMU and libvirt tied together with python code. This system is used daily for automated testing as well as by most libreswan developers when working on specific code. Anyone can run these tests on their server or laptop as documented at Test_Suite

Daily test results are available at Daily Test Results and an example run can be found at

There are currently around 600 test cases that involve booting 2 to 4 VMs to install various IPsec tunnels. The console output is captured, sanitized and compared against known good output. It takes about 8 hours to run and most of the time is lost waiting on VMs to startup and shutdown. Test cases consist of "init", "run" and "final" shell scripts that perform the actual test. You can browse our test cases at testing/pluto

Waiting 8 hours to see if a code change breaks anything is not pleasant. An attempt was made to speed things up dramatically using docker instead as documented at [Test_Suite_-_Docker]

Unfortunately, our experiment with docker turned out to be very slow as well, mostly due to the additional overhead of systemd and the plumbing to support multiple interfaces which we need for our tests.

Extend RFC-7427 Signature Authentication support to IKEv2 with ECC / EDDSA support

Required Skills: C programming, RFC interpretation, PKIX/X.509/ASN knowledge.

Libreswan Mentors: Tuomo Soini, Kim BCG

This project builds on top of last year's GSoC project to add support for RFC-7427.

IKEv2 performs authentication by using separate mechanism to specify the authentication method as specified in the IANA IKEv2 Authentication Method:

The IPsec Working Group at IETF realized using a separate number whenever a new algorithm is added is not very friendly for implements. It basically duplicates the OIDs and SubjectPublicKeyInfo data structures. RFC-7427 generalizes IKEv2 signature support to allow any signature method supported by PKIX and also adds signature hash algorithm negotiation.

Libreswan itself currently only supports RSA as digital signature authentication method, so it needs to be extended internally as well to be able to use other methods, such as ECDSA or EDDSA. Libreswan uses the NSS library for both PKCS#11 and for algorithm implementations.

Add EAP Authentication support to IKEv2

Required Skills: C programming, NSS or openssl crypto library, RFC interpretation

Libreswan Mentors: Tuomo Soini, Paul Wouters

Most EAP implementations are based on wpa_supplicant and openssl. Unfortunately, libreswan uses the NSS library. The student will investigate the options available and present o proposal justifying whether to use NSS or openssl.

Desired EAP implementations - most desired ones listed first:

Implement TLS Encapsulation of IKE and IPsec Packets

This project builds on last year's GSoC's project that added TCP support to IKE (and soon the Linux kernel will be able to support TCP for ESP) as per RFC 8229. The next step is to add support for IKEinTLS and IKEinESP support. This will enhance the protocol to be used in networks that only reliably allow HTTP and HTTPS traffic. The student would have to take a look at the kernel TLS support, and look at what the best way is for this support to be implemented - Via kernel TLS with a minimal userspace component for the handshake, or by pulling in all ESPinTLS packets from the kernel into the userland.

While we can assist a bit with the kernel work, we are not kernel developers. However, if someone is interested in this project, we will look and see if we can find a willing kernel developer to co-mentor.

Required Skills: C programming, Advanced Network Programming, RFC interpretation

Libreswan Mentors: Hugh Redelmeier, Paul Wouters

The libreswan IKE daemon basically consists of a libevent based loop that waits for events. Currently these events can be incoming UDP or TCP traffic, commands over a unix domain socket, timed events and crypto or DNS helper events. Listening to TLS streams in such a way as to not open up the daemon for DDoS attacks is required for this implementation. This requires some architecture work for which we have the original daemon author (Hugh) available as mentor.

Create a web based Certificate and Profile User Interface

Required Skills: Web backend coding (ruby, python, php) and the use of certificate/openssl related crypto modules for that language

Libreswan Mentors: Tuomo Soini, Paul Wouters

Currently, there are shell scripts for creating X.509 certificates, revoking certificates and signing CRLs and scripts for the creation of Profile files for certain devices such as Apple OSX and iOS. These require careful specification of various certificate attributes so that these certificates work on a variety of devices: Android, Windows, iOS/OSX, Linux, etc. The goal of this project is to gather all that knowledge into a simple to use interface that supports:

  • Generating the proper ipsec.conf configuration based on web admin interface including DNS / split-DNS configurations
  • Allow Administrator to input only an email address to send an invite to a new user
  • A new user can arrive at the portal, pick up their certificate/profile (over TLS)
  • The web portal will not allow the profile/cert to be downloaded more then once
  • Admin page allows listing/revocation/disabling of certificates
  • disable is implemented using pam_url auth to a localhost script
  • Generate PKCS#12 certificates for endusers
  • Generate iOS/OSX .mobileconfig profiles for automatic installation on OSX / iOS
  • Look at generating profile for automatic installation on Windows (maybe using vpnclient
  • Support ipsilon for existing user authentication to web application - work with Fedora Project to roll out VPN webapp.
  • configure the system with IP forwarding, iptables SNAT/MASQ, etc when needed.
  • configure munin-node to work with libreswan plugin (see

Extend the Linux NetworkManager plugin for IKEv2 based connections

Required Skills: C programming, Advanced Network Programming, RFC interpretation

Libreswan Mentors: Hugh Redelmeier, Paul Wouters

Over at the GNOME Projects lives the NetworkManager-libreswan plugin for libreswan. This Linux Desktop application currently only supports XAUTH (aka Cisco IPsec) using IKEv1 and PreShared Keys. The goal of this project is to extend this to support IKEv2 based VPNs as well as certificate based authentication. This project will be using a new dbus interface to better integrate with both NetworkManager and libreswan. Libreswan;s dbus API is currently being developed.

Opportunistic IPsec development using LetsEncrypt

Required Skills: DevOps, scripting (python, shell), PKIX/X.509

Libreswan Mentors: Paul Wouters, Tuomo Soini

Opportunistc IPsec is an attempt to encrypt the internet at large. The idea is to build VPN tunnels directly to all internet hosts irrespective of the communication used. This concept has its origins with The FreeS/WAN Project started by John Gilmore in late 90's. An initial proof of concept was created that leverages LetsEncrypt certificates for use with IKE and IPsec. The goal of this project is to turn this proof of concept into production quality code that makes it trivial to enroll and deploy on any server and any client.

  • Automate the enrollment and updating of LetsEncrypt certificates for use with libreswan
  • Implement a DNS / DNSSEC based method for advertising Opportunistic IPsec support using LetsEncrypt for servers
  • Design a non-DNS based method for publishing support of LetsEncrypt based Opportunistic IPsec for servers
  • Enhance libreswan to allow a secure fallback to the existing NULL Authentication nethod

Support for AF_KEY symmetric crypto via kernel calls

Currently, the symmetric crypto (as well as user authentication via X.509) happens via NSS. We are looking at converting the symmetric crypto operations of IKE (not X.509 authentication) to be done by the kernel via its AF_KEY sockets. A new config setup option would determine which of the two crypto providers to use.

Extend MOBIKE support to allow it to be used as server failover mechanism

See RFC 4555 and

support for RFC 5685: IKEv2 Redirect

Add support for RFC 5685

This document defines an IKEv2 extension that allows an overloaded VPN gateway or a VPN gateway that is being shut down for maintenance to redirect the VPN client to attach to another gateway. The proposed mechanism can also be used in Mobile IPv6 to enable the home agent to redirect the mobile node to another home agent.

This RFC might not be enough for the entire GSoC period. If done early, the student is expected to start work on another small RFC

Support for RFC 5723: IKEv2 Session resumption

Add support for RFC 5723

In order to avoid the need to re-run the key exchange protocol from scratch, it would be useful to provide an efficient way to resume an IKE/IPsec session. This document proposes an extension to IKEv2 that allows a client to re-establish an IKE SA with a gateway in a highly efficient manner, utilizing a previously established IKE SA.

This RFC might not be enough for the entire GSoC period. If done early, the student is expected to start work on another small RFC

Support for RFC 6023: Childless IKE SA

Add support for RFC 6023

This document describes an extension to the Internet Key Exchange version 2 (IKEv2) protocol that allows an IKEv2 Security Association (SA) to be created and authenticated without generating a Child SA.

This RFC might not be enough for the entire GSoC period. If done early, the student is expected to start work on another small RFC

Support for RFC 6290: Quick Crash Recovery

Add support for RFC 6290

This document describes an extension to the Internet Key Exchange Protocol version 2 (IKEv2) that allows for faster detection of Security Association (SA) desynchronization using a saved token.

When an IPsec tunnel between two IKEv2 peers is disconnected due to a restart of one peer, it can take as much as several minutes for the other peer to discover that the reboot has occurred, thus delaying recovery. In this text, we propose an extension to the protocol that allows for recovery immediately following the restart.

This RFC might not be enough for the entire GSoC period. If done early, the student is expected to start work on another small RFC

= Support for RFC 7670: Generic Raw public key support

Add support for RFC 7670

The Internet Key Exchange Version 2 (IKEv2) protocol did have support for raw public keys, but it only supported RSA raw public keys. In constrained environments, it is useful to make use of other types of public keys, such as those based on Elliptic Curve Cryptography.

Support for multiple IPsec SA's per exchange

Multiple traffic selectors can be included in an IPsec SA request, which could aid in the setup of multiple "connections" using a single Exchange. This method is used by the openbsd iked software.

Implement this support and confirm with interop tests that this works as expected.


Various experimental non-standard feature ideas

See our list of requested features for the Linux IPsec summit:

These are all Linux kernel related options

Re-port the libreswan code for FreeBSD / OSX

It would need to update/extend the PF_KEY API currently defined. See programs/pluto/kernel_*

Re-port the libreswan code for Microsoft Windows

This would possibly use the new linux subsystem in Windows? Or it would use the windows IPsec kernel code, and use modern windows features to configure these from the libreswan IKE daemon pluto. Possibly use powershell commands like Set-VpnServerConfiguration and Set-VpnServerIPsecConfiguration.

The goal would be to support Opportunistic IPsec and/or build a replacement IKEv2 VPN client.

An ancient, possibly completely useless Win2000 hook is located in programs/pluto/kernel_win2k.c

Cleanup / maintenance / code deduplication

Everyone wants features, no one wants maintenance :)

The codebase has too many comments that point to an issue needing maintance in some way. A code rewrite, a corner case handling, an oddity. A pointer to code duplication. Refactoring long functions.

This could combine with better splitting IKEv1 and IKEv2 code, so that ikev1 can be not compiled in for the future (via a new USE_IKEv1=true|false compile time option)

Similarly, a code cleanup could be started to remove KLIPS support (but not PF_KEY support)

Detect kernel algorithms supported for IPsec

We are currently using an obsoleted API to determine what algorithms the kernel supports. We then manually hack the reply, because we know the kernel lies to us about certain support.

See also: xfrm_probe_algs(), init_pfkey() and kernel_alg_register_pfkey()

Related, we might want to trigger some crypto algorithm modules to load, but can we?

(We hope to know a bit more after the Linux IPsec summit on what would be involved for this work itme)