Research: Resilio Sync.

Updated 07 July 2018

Copyright: European Union Public License, version 1.2 (EUPL-1.2).

Contents of this Article

  1. About.
  2. Basic Navigation and features.
  3. Folder States
  4. Mobile Device Usage
  5. Resilio in action.
  6. Summary

1 – About.

Resilio Sync is a peer-to-peer networking tool that allows individuals or groups to file share over a secure line. Essentially, the software forms a network of interconnected devices that then share resources with one another. The functions that this software provides is wide ranging. For example, a small development team that is working on a collaborative project can quickly share files between one another. A small business can theoretically have their own server with this application, allowing employees to access files and directories. The product also has individual usage in the home by turning a computer into a mapped network drive. Resilio is a reflection of Ubinodes core values, which are security then productivity. Security always comes first and the software utilizes a wide range of network protocols to accomplish specific tasks. For example, if peers are located in a Local Area Network (LAN), Resilio will use UDP port 3838 to sync with other peers. When a Sync occurs over the Internet Resilio uses automatic port mapping over UPnP and NAT-PMP. Network mapping is done based on the best route in mind, therefore Resilio is constantly switching between UDP and TCP protocols. All of which maintains the security of files in transit and reduces the downtime for workers.

2 – Basic Navigation and features.

2 – 1 Preferences.

  • General.

The General tab within the preferences section lists criteria such as Device Name, Updates, Startup, default folder location file download location, and software version. These options control which files and directories sync will access. Furthermore, this is the first place you will go when checking for updates.

  • Identity.

This option allows a user to unlink the device that is used to connect to peers.

  • Advanced.

Within the Advanced tab a user can make changes to sync’s bandwidth, connecting port and debug logging. The most important option under this setting is the ability to manually switch between UDP and TCP protocols.

  • License.

In this tab you will be able to purchase the license for the pro version of the software.

  • Support.

Here a User can access the help center or ask a question in the community forum. If a user contacts the help center via email, they should receive a response within 24 hours.

2 – 2 History

The history section is where a user will go to find their previous uploads and syncs. A user can search uploads by criteria such as errors, warnings, info and activity. Once the you select a search criterion, you will see some meta data about the files that have been sent previously. Starting from the left you are presented with a time stamp which indicates the day and time of the upload. Next, is the peer who published the file or folder. Moving forward is the source folder and the event which is the file path of the file. If you know which file you are looking for, you can use the search bar at the top right side of the page. At the bottom left of the page is the pause syncing option. Since Resilio is continuously updating, you can see when a file is being synced.

2 – 3 Adding Folders

There are two methods to add and share a folder, the first way to add a folder in Resilio is to left click the share button then drag and drop the folder from your file location into the window. This first method will allow a user to share files with other connected devices and peers. Within this menu you can set permissions to files as Read Only or Read & Write. In the key portion of this window, you are given separate keys for Read Only and Read & Write. You can then send invites to peers to access a resource. The creator of these invites can set an expiration on the invite and choose to send the invite via email or by manually copying the link. The Read Only and Read & Write permissions can also be done with the use of a QR code, a user would just need to use their mobile phone to scan the code to gain that key. Resilio gives the creator of these files the ability to choose its method of security, making it a flexible tool.

The second way that a user can add a new folder is through the plus icon in the top left corner of the application. Once you have left clicked the plus icon, the user will be presented with three folder type options (Standard folder, Advanced folder and encrypted folder).

Standard Folders – This option is the preferred option when you want to sync folders with multiple devices. The users are also able to give and control permissions to a folder.

Advanced Folders – A user may want to choose this option when collaborating with multiple people. As the owner of this type of folder you are able to edit and revoke access permissions at any moment. This folder type is only available for the pro version of Resilio.

Encrypted Folders – This folder type is preferred when syncing to a third-party server where you need to confirm that data is not sent in plain text. Along with the standard folder functionality you can encrypt data on trusted devices.

Inside of the add folder menu, there are two options that allow a user to share a file and enter a key or link. The share file button is utilized in the same way as the first share file option mentioned above. The Enter a key or link button is used when you need to receive a folder from someone else. Here you will manually enter the key when prompted.

2 – 4 Remove a Folder

To remove a folder, you first want to navigate to the folder Icon in the navigation bar, then left click the folder icon. Once you have located the folder that you want to remove hover over the sub-menu icon and left click to display the dropdown menu. The option that you want to select is remove; this will only delete the folder in sync not on the local machine.

3 – Folder States

The pending folder state is activated when the folder requires approval from the owner of the folder. This folder type will not be activated if you have been approved by the owner before you access the folder and when approved the folder will connect the storage device is online. The disconnected folder type does not take up any of your hard drive space and has no folder path until it’s connected. When a disconnected folder is removed it will be removed from all other linked devices.

Selective Sync

When a folder has selective sync enabled that folder will take up a minimal amount of drive space. The actual files inside of a selective sync folder are substituted by a placeholder file. Once a placeholder file is double clicked Resilio will then fetch the full length file on the source device. This feature is meant to save a user’s hard drive space.

Full Sync 

A full sync occurs when all of the files in a folder are synchronized between all devices. This process is done automatically and disables selective sync.

Read only

These folders restrict the user from making any changes, removals or deletions to the contents of a folder. At times your local settings may be able to make changes to your local copy of read only synced files. Consequently, if you do this then you will not be able to receive updates on the read only file. The crown symbol below represents that you are the owner and you can give your peers access to it.


This folder design acts as a backup location in an untrusted environment. An example of this would be when you add an encrypted folder to a VPS, by doing this you are avoiding the risk of your data being read by unauthorized persons.

Folder Legend

4 – Mobile Device Usage

Here I will be discussing the available Sync settings on major mobile devices which include Android and iOS. To download the mobile application on your phone, you first want to go to the app store hosted on your phone and download it from there.

To understand the mobile version of the application and all its settings, we are going to create and link a test folder to see the details within the mobile version. Start by creating a new folder by tapping the “+” button followed by selecting the folder type you want. To link to a computer, copy the key given to you in the details window of the folder.  For the purposes of this demonstration I just created a folder, but you can link a folder with a QR code or key.

Once the folder is created, you create sub-folders and share files from your phone with peers. You can also manage connected folder rights and permissions from your phone. You have the same options on mobile that you have on the desktop version of the application except, add backup. The add backup option is exclusive to the mobile versions of the application and can be used to backup your files and folder on your mobile device to a desktop. The Sub-menu option offers  users the ability to see their connected devices, the setting and shared links. The most important of these options is the settings tab. Here you will be able to set permission, pause and disconnect folders. Also, the setting tab can be used to change the applications network settings. This includes adding hosts, using a relay server or searching for a LAN.

5 – Resilio in action

Resilio Sync utilizes many ports and protocols to connect peers. The majority of out of network communication is done with TCP and UDP protocols. The first thing that Sync needs to do is learn the route to the relay servers that connect peers and clients. Below is an example of this and as you can see, Resilio is sending a Syn request from a local machine to the service provider’s gateway server. After it has learned the path to the relay server, it downloads and saves this information into the sync.conf file. Sync’s listening port is shown in the settings portion of the application and is determined by the users firewall or forwarding devices. If we look at the example below, the application uses the TCP source port 51262 to reach out to the relay server.

Resilio coordinates it’s networking to find the best route for data. This in turn makes synchronization instantaneous and keeps peers up to date on the status of files. Resilio ensures that the packets sent over the network/Internet are undecryptable by using AES256 PKI based encryption over TLS 1.2. Securing file transfers is the deciding factor when deciding on which file sharing application you want to use. The Networking features offered by Resilio keep the workflow moving while users can automatically send and receive updates on files in real-time. When compared to other file sharing programs like FileZilla and WinSCP, Resilio has proven that it can solve more of the security issues that are involved With FTP. Which ensure that the files and connections are not intercepted by threat actors.

6 – Summary

Resilios is a great tool for synchronizing data with peers over the network within a short amount of time. The reason why this file sharing tool is such a good fit for Ubinodes is due to its security management features which include SHA-256 hashing and TCP/UDP forwarding protocols. In your time here at Ubinodes, you will interact with Resilio on a daily basis. Consequently, it is suggested that you become familiar with the ins and outs of the program. Resilio has a free version and a Pro version of the application. This review focused on the free version since we do not require users/employees to purchase software. Users are welcomed to purchase a pro license to Resilio; with that pro license users link folders with peers and devices without having to create a host folder. Resilio Sync can give users the ability to share files instantaneously which provides numerous uses for business operations. The good thing about sync is that the network is never offline; a folder may be unavailable because your computer is turned off but your employees can still continue to work. This provides more up-time for employees which in turn increases productivity. Here at Ubinodes, we prefer to use  Resilio over other cloud service providers due to the cost in maintaining cloud infrastructure. Resilo is easy to use and cost efficient.

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