Privacy Blog

"Friends don’t let friends get spied on.' – Richard Stallman, President of the Free Software Foundation and longtime advocate of privacy in technology.


Do you use two or more computers? Perhaps you have a desktop system and a laptop computer. Perhaps you use one computer at the office and a different one at home. Then again, perhaps you have two homes; a summer cottage or perhaps one home in the sunbelt and another “up north.” Do you keep separate computers in each location?

Perhaps you and a relative who is also working on the family tree want to keep genealogy information and old family photographs updated all the time in both of your computers in your homes. Whatever your situation, the question this article hopes to answer is, “How do you automatically keep some of the information up-to-date on both (or all) of the computers?”

The question can be answered with one word: Syncthing.

Here is a quote from the website:

“Syncthing is a continuous file synchronization program. It synchronizes files between two or more computers in real time, safely protected from prying eyes. Your data is your data alone and you deserve to choose where it is stored, whether it is shared with some third party, and how it’s transmitted over the internet.”

In short, the name of “Syncthing” is appropriate. It is a FREE and open source piece of software that is designed to keep some (or all) of the information in 2 or more computers automatically synchronized all the time with minimal human action required. It works amongst side-by-side computers at home or computers separated across the country or even across the world.

Syncthing apparently can copy everything although I suspect the more common use is to duplicate one or more folders (sub-directories) in two or more computers.

Syncthing is available free of charge for Macintosh OS X, Microsoft Windows, Linux, FreeBSD, Solaris and OpenBSD. The program has been available for several years and has many thousands of satisfied users. In short, it is well tested.

NOTE: Wikipedia at defines FOSS as:

“Free and open-source software (FOSS) is software that can be classified as both free software and open-source software. That is, anyone is freely licensed to use, copy, study, and change the software in any way, and the source code is openly shared so that people are encouraged to voluntarily improve the design of the software. This is in contrast to proprietary software, where the software is under restrictive copyright licensing and the source code is usually hidden from the users.”

Syncthing is Private & Secure

Again, quoting from the Syncthing web site:

Private. None of your data is ever stored anywhere else other than on your computers. There is no central server that might be compromised, legally or illegally.

Encrypted. All communication is secured using TLS. The encryption used includes perfect forward secrecy to prevent any eavesdropper from ever gaining access to your data.

Authenticated. Every node is identified by a strong cryptographic certificate. Only nodes you have explicitly allowed can connect to your cluster.


Easy to Use

Powerful. Synchronize as many folders as you need with different people or just between your own devices.

Portable. Configure and monitor Syncthing via a responsive and powerful interface accessible via your browser. Works on Mac OS X, Windows, Linux, FreeBSD, Solaris and OpenBSD. Run it on your desktop computers and synchronize them with your server for backup.

Simple. Syncthing doesn’t need IP addresses or advanced configuration: it just works, over LAN and over the Internet. Every machine is identified by an ID. Give your ID to your friends, share a folder and watch: UPnP will do if you don’t want to port forward or you don’t know how.

In short, Syncthing is easy to use and doesn’t share any of your data on some questionable company’s web site. In fact, it doesn’t even upload anything to a web site or corporate server; all data is sent between the computers you specify and to no place else. If you still have concerns, you can even examine the source code yourself and even compile your own version of Syncthing. Syncthing is available FREE of charge.

I have been using Syncthing to keep several folders on two computers up-to-date with each other for more than a year and have been pleased with its operation. Even though these two computers are 1,200 miles apart, Syncthing has proven to be very reliable.

The local power companies and internet companies have dropped power and/or internet connectivity at each location several times. Once the power and internet connectivity has been restored, each computer has powered up, rebooted (see the owners’ manuals for information on how to automatically re-boot your computers after a power outage), and continued running Syncthing in normal operation.

You can read more about Syncthing or even download the free program at:

Categories: Security, Software

1 reply

  1. Syncthing requires opening a port in the router firewall at at least one of the two locations. Maybe both, it is not clear. This is a security hole and seems to be minimized at the website. Bad guys scan for open ports all the time. All the time. The documentation on firewall setup at the syncthing website is frankly quite poor, almost to be incomprehensible.


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