Syncthing Windows Setup

Syncthing Windows Setup is a lightweight yet full-featured Windows installer for the open-source Syncthing file-synchronization application.

---

Table of Contents

• System Requirements
• Download
• Background
• Version History
• Upgrading Administrative Installations
• Downgrading an Installation
• Setup Command Line Parameters
• Administrative vs. Non Administrative Installation Mode
  • Non Administrative (Current User) Installation Mode
  • Administrative (All Users) Installation Mode
• Windows Service Installation
  • Local User Service Account Considerations
• Granting Folder Permissions for the Service Account
• Setup Tasks
• Start Menu Shortcuts
• Managing Automatic Startup
  • Managing Automatic Startup for the Current User
  • Managing Automatic Startup for the Windows Service (All Users)
• Checking If Syncthing Is Running
  • Checking if Syncthing is Running for the Current User
  • Checking if Syncthing is Running as a Service
• Windows Firewall Rules
  • Firewall Rule Creation
  • Creating the Firewall Rule Manually
  • Firewall Rule Removal
  • Removing the Firewall Rule Manually
• Helper Tools
• Resetting the Service Account Password
• Finding the Syncthing Configuration Folder
• Uninstalling Syncthing
• Silent Install and Uninstall
  • Silent Non Administrative (Current User) Installation
  • Silent Administrative (All Users) Installation
  • Silent Uninstall
• Reporting Problems
• Acknowledgments

---

System Requirements

Syncthing is compiled using the Go programming language, which requires a recent operating system version. Accordingly, installing Syncthing using Syncthing Windows Setup requires Windows 10 or later.

Download

You can download the latest version from the Github Releases page:

https://github.com/Bill-Stewart/SyncthingWindowsSetup/releases/

Background

Syncthing Windows Setup (herein referred to as "Setup") provides a Syncthing installer for Windows, built using Inno Setup. It provides the following features:

• Installs the appropriate Windows platform (AMD64, etc.) version of Syncthing using a single installer

• Supports non administrative (current user) and administrative (all users) installation (see Administrative vs. Non Administrative Installation Mode)

• When installing for the current user, Setup creates a scheduled task that starts Syncthing at logon (if selected)

• When installing for all users, installs Syncthing as a Windows service using shawl (see Windows Service Installation)

• Supports adding a Windows Firewall rule for Syncthing (see Windows Firewall Rules)

• Installs a set of helper tools for ease-of-use (see Helper Tools)

• Supports silent (hands-free) installation (see Silent Install and Uninstall)

• Allows localization of Setup and scripts (see building.md file for details)

Version History

See history.md.

Upgrading Administrative Installations

Administrative installations in versions 1.19.1 and older configured the Windows service to run using the Windows built-in LocalService account. To improve security, Setup versions newer than 1.19.1 configure the Windows service to run using a local service user account instead (SyncthingServiceAcct by default). As a part of this change, the Syncthing configuration data is now located in the CommonAppData\Syncthing folder (e.g., C:\ProgramData\Syncthing).

If you upgrade an administrative installation from version 1.19.1 or older, Setup version 1.27.0 and newer will uninstall the old version and install the new version, but it will no longer migrate the configuration data. Because of this change, it is recommended to first upgrade to version 1.26.1 to migrate the configuration data, and then upgrade again to version 1.27.0 or later.

Downgrading an Installation

To downgrade an installation, first uninstall the current installed version, and then reinstall the older version. (Keep in mind that the Syncthing executable will automatically upgrade itself unless automatic upgrades are disabled.)

Setup Command Line Parameters

The following table lists the most common Setup command line parameters:

Parameter	Description
/currentuser	Runs Setup in non-administrative (current user) installation mode (see Administrative vs. Non Administrative Installation Mode).
/allusers	Runs Setup in administrative (all users) installation mode (see Administrative vs. Non Administrative Installation Mode).
/dir="location"	Specifies the installation folder. The default installation folder depends on whether Setup runs in administrative (all users) or non administrative (current user) installation mode.
/group="name"	Specifies the Start Menu group name. The default group name is Syncthing.
/tasks="tasks"	Specifies the tasks for the Select Additional Tasks wizard page (see Setup Tasks).
/mergetasks="tasks"	Like /tasks, except Setup merges the specified tasks with the set of tasks that would have otherwise been selected by default.
/noicons	Prevents creation of a Start Menu group.
/silent	Runs Setup without requiring user interaction (see Silent Install and Uninstall).
/log="filename"	Logs Setup activity to the specified file. The default is not to create a log file.

See Inno Setup's documentation for more details about the above parameters.

In addition to the standard Inno Setup parameters, Setup also supports some custom command line parameters. The parameters marked with [*] correspond to the settings on the Select Configuration Settings page in Setup.

Parameter	Description
/autoupgradeinterval=interval	[*] Specifies the number of hours that Syncthing should check for upgrades and automatically upgrade itself. The default value is 12 hours. Specify 0 to disable automatic upgrades.
/listenaddress=address	[*] Specifies the listen address for the web GUI configuration page. The default listen address is 127.0.0.1.
/listenport=port	[*] Specifies the TCP port number for the web GUI configuration page. The default port number is 8384.
/relaysenabled=value	[*] Specifies whether relays are enabled (value must be either true or false). The default value is true (i.e., relays are enabled).
/serviceaccountusername=username	For administrative installation mode, specifies the local service user account user name. The default user name is SyncthingServiceAcct.
/noconfigpage	Prevents the "Open Syncthing configuration page" checkbox from appearing on the final Setup wizard page.

Please note the following:

• The /autoupgradeinterval parameter affects the syncthing.exe executable only (it does not download or run a new version of Setup). If this setting is greater than 0 and Syncthing detects a new version released by the Syncthing team on the Internet, only the syncthing.exe executable is upgraded.

• Please read the Syncthing documentation page about the GUI listen address before changing the listen address and port numbers from the defaults.

• For more information about relays, please see the Syncthing documentation page about relaying. Please note that relaying might trigger network security alerts if an outgoing connection is made to a relay network host on the Internet that is being shared by a network service prohibited by network security teams on business or government networks. It is recommended to check with network security teams before using Syncthing on these kinds of networks.

• It is recommended not to use the /serviceaccountusername parameter to change the local service account user name unless that user name is already in use for some other purpose.

Administrative vs. Non Administrative Installation Mode

Setup supports both non administrative (current user) and administrative (all users) installation modes. For an initial installation (not a reinstall or upgrade), Setup displays a dialog box requesting whether you want to install for the current user only (non administrative installation mode) or for all users (administrative installation mode). You can bypass the dialog by specifying either /currentuser or /allusers on Setup's command line (see Setup Command Line Parameters). When you run a newer version of Setup (i.e., an upgrade) or reinstall the current version, Setup does does not display the dialog. To perform an initial installation in silent mode (see Silent Install and Uninstall), you must specify either /currentuser or /allusers on Setup's command line.

The main advantage of installing in administrative (all users) installation mode is that Syncthing runs as a Windows service and runs without any users being logged on; however, you must manually configure folder permissions to add folders to the Syncthing configuration (see Granting Folder Permissions for the Service Account).

See below for the differences between the two modes.

Non Administrative (Current User) Installation Mode

The following notes apply to non administrative (current user) installation mode:

• Setup installs Syncthing for the current user only

• The default installation folder is LocalAppData\Programs\Syncthing (where LocalAppData is the current user's local application data folder; e.g., C:\Users\UserName\AppData\Local)

• Setup does not install Syncthing as a Windows service

• By default, Setup creates a scheduled task that starts Syncthing in the background when the current user logs on (you can change this by deselecting the checkbox on the Select Additional Tasks wizard page)

• Syncthing runs only when the installing user logs on

• Starting and stopping Syncthing is managed by Start Menu shortcuts

• Setup prompts to create a Windows firewall rule for Syncthing (requires administrative permissions)

• By default, Setup starts Syncthing after installation completes if a firewall rule exists for it; you can change this by deselecting the checkbox on the last Setup wizard page or by specifying the /nostart parameter on Setup's command line

• No folder permission changes are required to add the current user's folders to the Syncthing configuration

• Administrative permissions are not required to make changes to files in the Syncthing configuration folder

Administrative (All Users) Installation Mode

The following notes apply to administrative (all users) installation mode:

• Setup installs Syncthing for all users of the computer

• The default installation folder is ProgramFiles\Syncthing (where ProgramFiles is the system's Program Files folder; e.g., C:\Program Files)

• Setup installs Syncthing as a Windows service (see Windows Service Installation)

• By default, Syncthing starts automatically when the system boots (you can change this by deselecting the checkbox on the Select Additional Tasks wizard page)

• Syncthing runs as a service and synchronizes folders even when no users are logged on

• Starting and stopping Syncthing is managed by stopping and starting the Windows service

• Setup automatically creates a Windows firewall rule for Syncthing

• By default, Setup starts the Syncthing service after installation completes; you can change this by deselecting the checkbox on the last Setup wizard page or by specifying the /nostart parameter on Setup's command line

• You must manually grant folder permissions for folders you want to add to the Syncthing configuration (see Granting Folder Permissions for the Service Account)

• Administrative permissions are required to make changes to files in the Syncthing configuration folder

Windows Service Installation

When you run Setup in administrative (all users) installation mode, it installs a Windows service for Syncthing using shawl. The service runs using a local service account (SyncthingServiceAcct by default). By default, Setup configures the service to start at boot. You can change this default by deselecting the startatboot task when installing (see Setup Tasks).

Local User Service Account Considerations

In administrative installation mode, Setup setup creates or updates the local service user account (SyncthingServiceAcct by default) with a very long, random password and configures the following settings for the account:

• It sets the account's password not to expire

• It grants the account the Log on as a service user right

If the computer is joined to a domain, be aware that Group Policy Object (GPO) settings might override either or both of these settings for the local service user account, which can prevent the service from working. If GPO settings override either or both of these settings, you can do either of the following:

• Uninstall the administrative installation of Syncthing and install for the current user instead, or

• Update the relevant GPO(s) to prevent overriding of the setting(s).

Granting Folder Permissions for the Service Account

In administrative (all users) installation mode, Syncthing runs as a Windows service using a local service user account (SyncthingServiceAcct by default). Normally the local service user account does not have permissions to folders you want to synchronize using Syncthing. This means you must grant the local service user account "Modify" permissions to any folders specified in the Syncthing configuration.

You can grant the local service user account "Modify" permissions to a folder using the Windows File Explorer. Alternatively, you can run the icacls command from the command line; e.g.:

icacls "C:\Users\username\Documents" /grant "SyncthingServiceAcct:(OI)(CI)M" /t

Of course, replace C:\Users\username\Documents with the correct folder name, and replace SyncthingServiceAcct with the correct service account user name if you changed the default service account user name.

Once the local service user account has "Modify" permissions for the folder, you can add it to the Syncthing configuration.

NOTE: Granting folder permissions is normally only needed if you installed Syncthing in administrative (all users) installation mode.

Setup Tasks

The Select Additional Tasks wizard page in Setup specifies additional tasks that Setup should perform. Available tasks depend on whether Setup runs in non administrative (current user) or administrative (all users) installation mode.

Task Description	Name	Installation Mode
Start Syncthing automatically when logging on	startatlogon	Current user
Start Syncthing after installation	startafterinstall	Current user
Start Syncthing service automatically when system boots	startatboot	All users
Start Syncthing service after installation	startserviceafterinstall	All users

The /tasks and /mergetasks command line parameters (see Setup Command Line Parameters) specify which tasks are selected (by default, all tasks are selected).

Start Menu Shortcuts

Setup creates the following Start Menu shortcuts, depending on the installation mode:

Shortcut	Installation Mode	Description
Syncthing Configuration Page	Both	Opens the Syncthing GUI configuration page using the default browser
Start Syncthing	Current user	Starts Syncthing in the background for the current user
Stop Syncthing	Current user	Stops the Syncthing instance running for the current user

• The Syncthing Configuration Page shortcut opens the ConfigurationPage.url file in the Syncthing installation folder (i.e., it opens the Syncthing GUI configuration page).

• The Start Syncthing and Stop Syncthing shortcuts run the stctl.exe tool to start and stop Syncthing (see Helper Tools).

Managing Automatic Startup

Setup configures Syncthing to start automatically by default, unless you deselect the startatlogon or startatboot task (see Setup Tasks). You can change this configuration after installation if needed. The steps for changing the configuration depends on whether you installed using non administrative (current user) or administrative (all users) or installation mode.

Managing Automatic Startup for the Current User

If you installed Syncthing for the current user, Setup creates a scheduled task that starts Syncthing automatically when the current user logs on. Setup does not create this task if you deselect the startatlogon task (see Setup Tasks) when installing.

If you did not select the startatlogon task when installing and want to create the task, do either of the following:

1. Open a command prompt or PowerShell window.

2. Run the following command:

   cscript "C:\Users\username\AppData\Local\Programs\Syncthing\SyncthingLogonTask.js" /create
   

   (where C:\Users\username\appData\Local\Programs\Syncthing is the Syncthing installation folder; replace username with the correct username)

OR

• Reinstall Syncthing and select the startatlogon task (i.e., the Start Syncthing automatically when logging on checkbox on the Select Additional Tasks page).

If you want to disable the logon task instead, do the following:

1. Open the Windows Task Scheduler application.

2. Right-click the Start Syncthing at logon (username) task and choose Disable.

Managing Automatic Startup for the Windows Service (All Users)

If you installed Syncthing for all users (i.e., the Windows service is installed), do the following:

1. Open the Windows Services application.

2. Double-click the Syncthing service.

3. Change Startup type to Automatic (Delayed Start) or Manual, then Click OK.

OR

• Reinstall Syncthing and select or deselect the startatboot task (i.e., the Start Syncthing service automatically when system boots checkbox on the Select Additional Tasks page).

Note that these steps require administrative permissions.

Checking If Syncthing Is Running

This section describes how to check if Syncthing is running.

Checking if Syncthing is Running for the Current User

If you ran Setup in non administrative (current user) mode, do one of the following:

1. Open the Windows Task Manager application.

2. Switch to the "details" view to see the list of running applications.

3. Check whether syncthing.exe is in the list.

OR

1. Open a command prompt or PowerShell window.

2. Enter the following command:

    tasklist /fi "imagename eq syncthing.exe"
   

   The output of this command will indicate whether Syncthing is currently running.

NOTE: No matter whether you use the Task Manager application or the tasklist command, is is normal for syncthing.exe to be listed more than once in the output.

Checking if Syncthing is Running as a Service

If you ran Setup in administrative (all users) installation mode, do the following:

1. Open the Windows Services Application.

2. Find the Syncthing service in the list.

3. The Status column will indicate if the Syncthing service is running.

NOTE: The tasklist command in the previous section also works to check if the service is running, except that the Session Name column in the output will contain Services rather than Console.

Windows Firewall Rules

Syncthing requires permission to communicate through the Windows firewall. Creating and removing firewall rules requires administrative privileges.

Firewall Rule Creation

• If you run Setup in non administrative (current user) installation mode, Setup prompts to create a firewall rule for Syncthing if it doesn't exist. Setup will prompt for administrative credentials (if needed).

• If you perform a silent install in non administrative installation mode (see Setup Command Line Parameters), Setup does not create a firewall rule for Syncthing, and you must create it manually (see Creating the Firewall Rule Manually).

• If you run Setup in administrative (all users) installation mode, Setup creates a firewall rule for Syncthing automatically.

Creating the Firewall Rule Manually

If you ran Setup using non administrative installation mode and need to create a firewall rule for Syncthing manually, open a PowerShell or command prompt window and run the following command:

cscript "C:\Users\username\AppData\Local\Programs\Syncthing\SyncthingFirewallRule.js" /create

(where C:\Users\username\appData\Local\Programs\Syncthing is the Syncthing installation folder; ; replace username with the correct username)

Firewall Rule Removal

If you uninstall Syncthing (see Uninstalling Syncthing), the same considerations as above apply, except Setup removes the Syncthing firewall rule rather than creating it:

• An uninstall of a non administrative (current user) installation prompts to remove the Syncthing firewall rule if it exists (requires administrative permissions).

• A silent uninstall of a non administrative (current user) installation does not remove the Syncthing firewall rule, and you must to remove it manually. It is recommended to remove the firewall rule before performing a silent uninstall if uninstalling for the current user (see Removing the Firewall Rule Manually).

• An uninstall of an administrative (all users) installation removes the Syncthing firewall rule automatically, without prompting.

Removing the Firewall Rule Manually

If you installed using non administrative installation mode and need to remove the Syncthing firewall rule manually, open a PowerShell or command prompt window and run the following command:

cscript "C:\Users\username\AppData\Local\Programs\Syncthing\SyncthingFirewallRule.js" /remove

(where C:\Users\username\appData\Local\Programs\Syncthing is the Syncthing installation folder; replace username with the correct username)

Helper Tools

Setup installs a set of helper tools to the installation folder to facilitate ease-of-use, depending on the installation mode, as described in the following table.

Tool	Installation Mode	Description
SetSyncthingConfig.js	Both	Setup uses this script to create and/or configure the Syncthing configuration file (config.xml).
SyncthingFirewallRule.js	Both	Adds, removes, and tests for the existence of a Windows firewall rule for Syncthing (prompts for administrative permissions if required).
SyncthingLogonTask.js	Current user (non admin)	Adds or removes a scheduled task that runs the StartSyncthing.js script at logon.
stctl.exe	Current user (non admin)	Helper program for starting and stopping Syncthing for the current user.
asmt.exe	All users (admin)	Helper program for installing and/or resetting the service account and service configuration.
ServMan.exe	All users (admin)	Helper program for starting and stopping the Syncthing service.

Resetting the Service Account Password

If you installed using administrative (all users) installation mode, use the following steps to reset the service account password:

1. Open a PowerShell or cmd.exe window as administrator

2. Change to the Syncthing installation folder; e.g. cd "\Program Files\Syncthing"

3. Run the following command:

   .\asmt --reset --account=SyncthingServiceAcct --name=syncthing

This command will reset the service account's password to a long, random password and update the Syncthing service to start with the new password.

NOTE: If you changed the default service account username (not recommended), specify it after the --account= option.

Finding the Syncthing Configuration Folder

The location of the Syncthing configuration folder depends on whether you run Setup in non administrative (current user) or administrative (all users) or installation mode:

• If you installed for the current user, the Syncthing configuration folder is in the following location:

  LocalAppData\Syncthing

  where: LocalAppData is the current user's local application data folder (e.g., C:\Users\UserName\AppData\Local)

  Administrative permissions are not required to access this folder.

• If you installed for all users, the Syncthing configuration folder is in the following location:

  CommonAppData\Syncthing

  where: CommonAppData is the common application data folder (e.g., C:\ProgramData)

  Administrative permissions are required to access this folder.

Uninstalling Syncthing

You can uninstall Syncthing using the standard Windows application management list.

If you installed Syncthing in non administrative installation mode (current user only), the uninstall process prompts to remove the Syncthing firewall rule if it exists (this requires administrative permissions).

If you installed syncthing in administrative install mode, note that the uninstall process:

• Removes the Syncthing firewall rule

• Revokes the Log on as a service user right from the local service user account

• Disables (but does not delete) the local service user account

Regardless of whether you installed Syncthing in administrative or non administrative mode, the uninstall process does not remove any Syncthing configuration files. If you want to remove the Syncthing configuration folder, determine its location (see Finding the Syncthing Configuration Folder) and remove it after uninstalling.

Silent Install and Uninstall

Setup supports silent (hands-free) install and uninstall mode using the /silent command line parameter.

• See Setup Command Line Parameters for information about Setup's command line parameters.

• See the Inno Setup documentation for information about the uninstall program's conmmand line parameters.

Silent Non Administrative (Current User) Installation

To perform an initial install (i.e., not a reinstall or upgrade) silently in non administrative (current user) installation mode, specify the /currentuser and /silent command line parameters on Setup's command line. In this mode, Setup:

• Does not install the Windows service

• Does not create a firewall rule for Syncthing (this is because creating a firewall rule requires administrative permissions, which would cause a prompt that would prevent the silent installation from completing)

• Starts Syncthing for the current user if a firewall rule for Syncthing is already in place (unless you also specify /nostart on Setup's command line)

To ensure Syncthing works correctly after a non administrative (current user) silent installation, create the firewall rule manually (see Creating the Firewall Rule Manually) before starting Syncthing.

A silent reinstall or upgrade does not require the /currentuser parameter.

Silent Administrative (All Users) Installation

To perform an initial install (i.e., not a reinstall or upgrade) silently in administrative installation (all users) mode, specify the /allusers and /silent command line parameters on Setup's command line. In this mode, Setup:

• Installs the Windows service

• Automatically creates a firewall rule for Syncthing

• Starts the Syncthing service after installation completes (unless you also specify /nostart on Setup's command line)

A silent reinstall or upgrade does not require the /allusers parameter.

Silent Uninstall

To uninstall silently, specify /silent on the uninstaller's command line (the uninstaller executable is located in the uninstall directory inside the Syncthing installation folder).

If you installed Syncthing for the current user, you must remove the Syncthing firewall rule manually (see Removing the Firewall Rule Manually) before uninstalling silently.

Reporting Problems

If you encounter a problem with Setup or one of the helper tools, please inform the author by filing an issue on the Issues page:

https://github.com/Bill-Stewart/SyncthingWindowsSetup/issues

For Syncthing support (not related to Setup or the helper tools), please visit the Syncthing forum:

https://forum.syncthing.net/

Acknowledgments

Special thanks to the following:

• Syncthing maintainers

• mtkennerly for shawl

• Jordan Russell and Martijn Laan for Inno Setup