The company behind Zerotier have asked for feedback, stories and testimonials from people using their software, and as a more than happy user of their VPN software and network I am pleased to submit this article. I am not being paid for this. I make use of their free tier access, which currently meets my needs, although this may change as my circumstances change and my IoT and home network grows. I have been a very happy user for more than 5 years.

By way of a simple introduction, ZeroTier is a Virtual Private Network (VPN)
technology, which enables all your devices to connect to each other via a
separate, encrypted and controlled, software defined IP network, supporting both
IPV4 and IPv6.

Why is this useful? The Zerotier network provides routers on the Internet which
are used to route you packets. The beauty of this is that once you have
installed the ZeroTier client on your devices (all major operating systems,
including mobile device are supported), and authorised them on your network,
they can communicate directly with each other, as if they were on the same local
network.

My initial use case was so that I could access my home servers while away from
home, particularly from my home wiki from my phone and mobile devices.
Installing Zerotier removes the need to add port forwarding on my home router,
or install a ‘Demilitarized Zone’ (DMZ) on my home network. Zerotier also allows
all services to be available via to VPN, rather than having to open ports for
every service or server that I want to access.

Another application is for remote access to remote servers for support services.
The security implications need to be discussed with any customers, but having
Zerotier installed on the remotely supported computer allows access from any
other device which is also on the same Zerotier network. This was used to
remotely control a robot at an exhibition and directly interact with the passing
public. Like with all network services, the performance depends on the
underlying networks.

In a more recent example, there is a plug-in for Zeroier in Home Assistant,
which makes it almost effortless to setup secure access to my home management
system for all members of the family both inside and outsode the home.

When registering devices on your private network (identified by a 16 digit
hexi-decimal number, or 32 bits), you can explicitly set the IP address that
devices are allocated, which they get when they authenticate to the network.
Even though these IP addresses are private, if you have a register domain, it is
possible to create public DNS names for them, which gives you the ability to use
your private network in exactly the same way as you may setup a server on the
internet itself.

What all this means is that Zerotier allows you to use internet as a ‘first
class citizen’, rather than as a second or third, which has what has happened in
the past when end users (home and commercial) have been forced to use network
work-a-rounds like port forwarding, dynamic DNS websites, OpenVPN and
IPSEC/L2TP, other router based solutions, and even manually configured web
caching. No configuration change is required to maintain access, provided the
end device has reasonably unfiltered access to the internet.

It is definitely worth giving Zerotier a go if you need to access all your
devices that are on private networks, or even if you want to access public devices via an encrypted and secured subnet. The free subscription level allows registering up
to 25 devices across multiple private networks. Checkout their website at
https://www.zerotier.com/