yggdrasil-network.github.io/_posts/2020-02-21-release-v0-3-13.md

---
layout: post
title:  "Release v0.3.13"
date:   2020-02-21 09:00:00 +0000
author: Neil Alexander
---

### Release time!

Our last Yggdrasil release, v0.3.12, was merged a couple of months ago at the
end of November. For the most part we have seen good stability with the v0.3.12
builds, not to mention good adoption (with the crawler showing over 500 nodes
running it). Today we are releasing our next version, v0.3.13.

Many of our releases tend not to warrant blog post entries, especially given
that the changelog documents the changes. However, there's some fairly big news
points associated with this version therefore this post aims to discuss them in
a bit more detail.

#### TUN adapter changes

The first big talking point is that this is the first Yggdrasil release that
departs entirely from the Water library and replaces it with the Wireguard TUN
library. There are a few reasons why we decided to switch from Water to the
Wireguard library, but one of the most prominent is that it gives us better TUN
support across all platforms and allows us to finally remove TAP support
altogether.

At a high-level, TUN interfaces are effectively emulating "Layer 3" interfaces -
they deal only in IP packets - whereas TAP interfaces are emulating "Layer 2"
full-fat Ethernet interfaces.

To run in TAP mode, Yggdrasil not only had to add and remove Ethernet headers
for each packet, but it also has to implement an entire NDP implementation and
track MAC addresses in order to trick the host operating system into believing
that there was a real Ethernet domain on the other end of the adapter. Needless
to say, the amount of boilerplate code in order to make TAP mode work correctly
was significant and much of that code was very fragile.

Although we implemented NDP, we did not ever get around to implementing ARP,
which also meant that sending tunnel-routed IPv4 traffic over TAP interfaces
invariably did not work either. We have now been able to remove much of this
code and simplify the TUN code massively, closing the gaps between some of our
supported platforms.

There is one platform that is negatively impacted by this change and that's
NetBSD. The Wireguard TUN package that we are using currently has **no support
for NetBSD**, so we are also removing NetBSD as a supported target until the
necessary code appears upstream. To our knowledge, we don't have a base of
NetBSD users anyway, but we will aim to re-add this soon.

The `IfTAPMode` configuration option has now been removed from Yggdrasil
entirely and it will be ignored if specified. **If you are using TAP mode today,
then this will affect you**. Please make sure to check your Yggdrasil
configuration since this may result in interface naming changes and you may have
to update network settings in your host operating system.

Initially we added TAP support into Yggdrasil as it was the only way to support
Windows, since the OpenVPN driver that we used at the time only supported TAP
mode. Thankfully, this is no longer a problem, as the Wireguard project have
also released [Wintun](https://wintun.net), which is supported by the Wireguard
TUN library. The net result is that we gain TUN support on Windows and the
performance is *far* better than the buggy OpenVPN driver, which is a nice segue
into...

#### Windows installer and performance

We have spent a lot of time trying to improve the installation and setup
experience on Windows. This mostly falls into two areas.

The first is that using the Wintun driver has *massively* improved performance,
in some cases by hundreds of MB/s, and starting the Yggdrasil process is now
much more reliable too - it should no longer be necessary to restart Yggdrasil
due to cases of the TAP adapter not being set up or configured correctly.

The second is that we now automatically generate Windows `.msi` installers using
Appveyor, which means that installing or upgrading Yggdrasil is now simpler than
ever. It is no longer necessary to create directories, copy files and register
Windows services by hand - a marked improvement!

The installer also bundles the Wintun driver and it is installed automatically
if required, therefore there is no longer a need to hunt down and install the
OpenVPN TAP driver separately. We hope that these changes will help to encourage
adoption of Yggdrasil on Windows platforms by significantly reducing the barrier
to entry.

As in the previous section, Yggdrasil on Windows has gone from supporting TAP
mode only to now supporting TUN mode only. **This may mean that you need to
review your configuration**. If you no longer need the OpenVPN TAP driver on
your system, it is best to entirely uninstall it. It is also important to make
sure that the `IfName` configuration option in your `yggdrasil.conf` does not
specify the same name as an existing OpenVPN TAP interface or Yggdrasil may fail
to start.

#### End of the v0.3 release cycle

Generally we try, where possible, to avoid make any changes which would damage
backward compatibility with previous versions. The last version that had
breaking changes was v0.2.1 - over a year and a half ago. However, maintaining
backward compatibility so tightly also prevents us from improving the Yggdrasil
design in various ways.

Therefore, unless any serious bugs or security vulnerabilities appear, it is
very likely that this version will be the last in the v0.3 release cycle.
Instead, we will start working on the v0.4 release, which is likely to include a
number of breaking protocol changes and will be incompatible with v0.3 releases
as a result.

More information will be announced on the types of changes in v0.4 as they
happen - expect to see more blog posts and chatter in the Matrix channel on this
subject - but we will aim to give as much notice as possible before releases
occur that contain breaking changes.

#### Final mentions

In addition to the release notes above, I'd like to relay the message that
[@mwarning](https://github.com/mwarning) has a proposal open for a Google Summer
of Code (GSoC) project under the Freifunk umbrella, comparing a number of mesh
routing protocols including Yggdrasil. More information about the proposal is
available [here](https://projects.freifunk.net/#/projects?project=freifunk_meshnet_protocol_evaluation&lang=en).
If you are interested, please reach out!