Syncthing Configuration¶

Synopsis¶

$HOME/.config/syncthing
$HOME/Library/Application Support/Syncthing
%LOCALAPPDATA%\Syncthing

Description¶

New in version 1.5.0: Database and config can now be set separately. Previously the database was always located in the same directory as the config.

Syncthing uses a single directory to store configuration and crypto keys. Syncthing also has a database, which is often stored in this directory too. The config location defaults to $HOME/.config/syncthing (Unix-like), $HOME/Library/Application Support/Syncthing (Mac), or %LOCALAPPDATA%\Syncthing (Windows). It can be changed at runtime using the --config flag. In this directory the following files are located:

config.xml: The configuration file, in XML format.
cert.pem, key.pem: The device’s ECDSA public and private key. These form the basis for the device ID. The key must be kept private.
https-cert.pem, https-key.pem: The certificate and key for HTTPS GUI connections. These may be replaced with a custom certificate for HTTPS as desired.
csrftokens.txt: A list of recently issued CSRF tokens (for protection against browser cross site request forgery).

The database is stored either in the same directory as the config (usually the default), but may also be located in one of the following directories (Unix-like platforms only):

If a database exists in the old default location, that location is still used.
If $XDG_DATA_HOME is set, use $XDG_DATA_HOME/syncthing.
If ~/.local/share/syncthing exists, use that location.
Use the old default location (same as config).

The location of the database can be changed using the --data flag. The --home flag sets both config and database locations at the same time. The database contains the following files:

index-*.db: A directory holding the database with metadata and hashes of the files currently on disk and available from peers.

Config File Format¶

The following shows an example of a default configuration file (IDs will differ):

Note

The config examples are present for illustration. Do not copy them entirely to use as your config. They are likely out-of-date and the values may no longer correspond to the defaults.

<configuration version="35">
    <folder id="default" label="Default Folder" path="/Users/jb/Sync/" type="sendreceive" rescanIntervalS="3600" fsWatcherEnabled="true" fsWatcherDelayS="10" ignorePerms="false" autoNormalize="true">
        <filesystemType>basic</filesystemType>
        <device id="S7UKX27-GI7ZTXS-GC6RKUA-7AJGZ44-C6NAYEB-HSKTJQK-KJHU2NO-CWV7EQW" introducedBy="">
            <encryptionPassword></encryptionPassword>
        </device>
        <minDiskFree unit="%">1</minDiskFree>
        <versioning>
            <cleanupIntervalS>3600</cleanupIntervalS>
            <fsPath></fsPath>
            <fsType>basic</fsType>
        </versioning>
        <copiers>0</copiers>
        <pullerMaxPendingKiB>0</pullerMaxPendingKiB>
        <hashers>0</hashers>
        <order>random</order>
        <ignoreDelete>false</ignoreDelete>
        <scanProgressIntervalS>0</scanProgressIntervalS>
        <pullerPauseS>0</pullerPauseS>
        <maxConflicts>-1</maxConflicts>
        <disableSparseFiles>false</disableSparseFiles>
        <disableTempIndexes>false</disableTempIndexes>
        <paused>false</paused>
        <weakHashThresholdPct>25</weakHashThresholdPct>
        <markerName>.stfolder</markerName>
        <copyOwnershipFromParent>false</copyOwnershipFromParent>
        <modTimeWindowS>0</modTimeWindowS>
        <maxConcurrentWrites>2</maxConcurrentWrites>
        <disableFsync>false</disableFsync>
        <blockPullOrder>standard</blockPullOrder>
        <copyRangeMethod>standard</copyRangeMethod>
        <caseSensitiveFS>false</caseSensitiveFS>
        <junctionsAsDirs>false</junctionsAsDirs>
    </folder>
    <device id="S7UKX27-GI7ZTXS-GC6RKUA-7AJGZ44-C6NAYEB-HSKTJQK-KJHU2NO-CWV7EQW" name="syno" compression="metadata" introducer="false" skipIntroductionRemovals="false" introducedBy="">
        <address>dynamic</address>
        <paused>false</paused>
        <autoAcceptFolders>false</autoAcceptFolders>
        <maxSendKbps>0</maxSendKbps>
        <maxRecvKbps>0</maxRecvKbps>
        <ignoredFolder time="2022-01-09T19:09:52Z" id="br63e-wyhb7" label="Foo"></ignoredFolder>
        <maxRequestKiB>0</maxRequestKiB>
        <untrusted>false</untrusted>
        <remoteGUIPort>0</remoteGUIPort>
    </device>
    <gui enabled="true" tls="false" debugging="false">
        <address>127.0.0.1:8384</address>
        <apikey>k1dnz1Dd0rzTBjjFFh7CXPnrF12C49B1</apikey>
        <theme>default</theme>
    </gui>
    <ldap></ldap>
    <options>
        <listenAddress>default</listenAddress>
        <globalAnnounceServer>default</globalAnnounceServer>
        <globalAnnounceEnabled>true</globalAnnounceEnabled>
        <localAnnounceEnabled>true</localAnnounceEnabled>
        <localAnnouncePort>21027</localAnnouncePort>
        <localAnnounceMCAddr>[ff12::8384]:21027</localAnnounceMCAddr>
        <maxSendKbps>0</maxSendKbps>
        <maxRecvKbps>0</maxRecvKbps>
        <reconnectionIntervalS>60</reconnectionIntervalS>
        <relaysEnabled>true</relaysEnabled>
        <relayReconnectIntervalM>10</relayReconnectIntervalM>
        <startBrowser>true</startBrowser>
        <natEnabled>true</natEnabled>
        <natLeaseMinutes>60</natLeaseMinutes>
        <natRenewalMinutes>30</natRenewalMinutes>
        <natTimeoutSeconds>10</natTimeoutSeconds>
        <urAccepted>0</urAccepted>
        <urSeen>0</urSeen>
        <urUniqueID></urUniqueID>
        <urURL>https://data.syncthing.net/newdata</urURL>
        <urPostInsecurely>false</urPostInsecurely>
        <urInitialDelayS>1800</urInitialDelayS>
        <restartOnWakeup>true</restartOnWakeup>
        <autoUpgradeIntervalH>12</autoUpgradeIntervalH>
        <upgradeToPreReleases>false</upgradeToPreReleases>
        <keepTemporariesH>24</keepTemporariesH>
        <cacheIgnoredFiles>false</cacheIgnoredFiles>
        <progressUpdateIntervalS>5</progressUpdateIntervalS>
        <limitBandwidthInLan>false</limitBandwidthInLan>
        <minHomeDiskFree unit="%">1</minHomeDiskFree>
        <releasesURL>https://upgrades.syncthing.net/meta.json</releasesURL>
        <overwriteRemoteDeviceNamesOnConnect>false</overwriteRemoteDeviceNamesOnConnect>
        <tempIndexMinBlocks>10</tempIndexMinBlocks>
        <unackedNotificationID>authenticationUserAndPassword</unackedNotificationID>
        <trafficClass>0</trafficClass>
        <setLowPriority>true</setLowPriority>
        <maxFolderConcurrency>0</maxFolderConcurrency>
        <crashReportingURL>https://crash.syncthing.net/newcrash</crashReportingURL>
        <crashReportingEnabled>true</crashReportingEnabled>
        <stunKeepaliveStartS>180</stunKeepaliveStartS>
        <stunKeepaliveMinS>20</stunKeepaliveMinS>
        <stunServer>default</stunServer>
        <databaseTuning>auto</databaseTuning>
        <maxConcurrentIncomingRequestKiB>0</maxConcurrentIncomingRequestKiB>
        <announceLANAddresses>true</announceLANAddresses>
        <sendFullIndexOnUpgrade>false</sendFullIndexOnUpgrade>
        <connectionLimitEnough>0</connectionLimitEnough>
        <connectionLimitMax>0</connectionLimitMax>
        <insecureAllowOldTLSVersions>false</insecureAllowOldTLSVersions>
    </options>
    <remoteIgnoredDevice time="2022-01-09T20:02:01Z" id="5SYI2FS-LW6YAXI-JJDYETS-NDBBPIO-256MWBO-XDPXWVG-24QPUM4-PDW4UQU" name="bugger" address="192.168.0.20:22000"></remoteIgnoredDevice>
    <defaults>
        <folder id="" label="" path="~" type="sendreceive" rescanIntervalS="3600" fsWatcherEnabled="true" fsWatcherDelayS="10" ignorePerms="false" autoNormalize="true">
            <filesystemType>basic</filesystemType>
            <device id="S7UKX27-GI7ZTXS-GC6RKUA-7AJGZ44-C6NAYEB-HSKTJQK-KJHU2NO-CWV7EQW" introducedBy="">
                <encryptionPassword></encryptionPassword>
            </device>
            <minDiskFree unit="%">1</minDiskFree>
            <versioning>
                <cleanupIntervalS>3600</cleanupIntervalS>
                <fsPath></fsPath>
                <fsType>basic</fsType>
            </versioning>
            <copiers>0</copiers>
            <pullerMaxPendingKiB>0</pullerMaxPendingKiB>
            <hashers>0</hashers>
            <order>random</order>
            <ignoreDelete>false</ignoreDelete>
            <scanProgressIntervalS>0</scanProgressIntervalS>
            <pullerPauseS>0</pullerPauseS>
            <maxConflicts>10</maxConflicts>
            <disableSparseFiles>false</disableSparseFiles>
            <disableTempIndexes>false</disableTempIndexes>
            <paused>false</paused>
            <weakHashThresholdPct>25</weakHashThresholdPct>
            <markerName>.stfolder</markerName>
            <copyOwnershipFromParent>false</copyOwnershipFromParent>
            <modTimeWindowS>0</modTimeWindowS>
            <maxConcurrentWrites>2</maxConcurrentWrites>
            <disableFsync>false</disableFsync>
            <blockPullOrder>standard</blockPullOrder>
            <copyRangeMethod>standard</copyRangeMethod>
            <caseSensitiveFS>false</caseSensitiveFS>
            <junctionsAsDirs>false</junctionsAsDirs>
        </folder>
        <device id="" compression="metadata" introducer="false" skipIntroductionRemovals="false" introducedBy="">
            <address>dynamic</address>
            <paused>false</paused>
            <autoAcceptFolders>false</autoAcceptFolders>
            <maxSendKbps>0</maxSendKbps>
            <maxRecvKbps>0</maxRecvKbps>
            <maxRequestKiB>0</maxRequestKiB>
            <untrusted>false</untrusted>
            <remoteGUIPort>0</remoteGUIPort>
        </device>
    </defaults>
</configuration>

Configuration Element¶

<configuration version="35">
    <folder></folder>
    <device></device>
    <gui></gui>
    <ldap></ldap>
    <options></options>
    <remoteIgnoredDevice></remoteIgnoredDevice>
    <defaults></defaults>
</configuration>

This is the root element. It has one attribute:

version¶: The config version. Increments whenever a change is made that requires migration from previous formats.

It contains the elements described in the following sections and any number of this additional child element:

remoteIgnoredDevice¶: Contains the ID of the device that should be ignored. Connection attempts from this device are logged to the console but never displayed in the web GUI.

Folder Element¶

<folder id="default" label="Default Folder" path="/Users/jb/Sync/" type="sendreceive" rescanIntervalS="3600" fsWatcherEnabled="true" fsWatcherDelayS="10" ignorePerms="false" autoNormalize="true">
    <filesystemType>basic</filesystemType>
    <device id="S7UKX27-GI7ZTXS-GC6RKUA-7AJGZ44-C6NAYEB-HSKTJQK-KJHU2NO-CWV7EQW" introducedBy="">
        <encryptionPassword></encryptionPassword>
    </device>
    <minDiskFree unit="%">1</minDiskFree>
    <versioning>
        <cleanupIntervalS>3600</cleanupIntervalS>
        <fsPath></fsPath>
        <fsType>basic</fsType>
    </versioning>
    <copiers>0</copiers>
    <pullerMaxPendingKiB>0</pullerMaxPendingKiB>
    <hashers>0</hashers>
    <order>random</order>
    <ignoreDelete>false</ignoreDelete>
    <scanProgressIntervalS>0</scanProgressIntervalS>
    <pullerPauseS>0</pullerPauseS>
    <maxConflicts>-1</maxConflicts>
    <disableSparseFiles>false</disableSparseFiles>
    <disableTempIndexes>false</disableTempIndexes>
    <paused>false</paused>
    <weakHashThresholdPct>25</weakHashThresholdPct>
    <markerName>.stfolder</markerName>
    <copyOwnershipFromParent>false</copyOwnershipFromParent>
    <modTimeWindowS>0</modTimeWindowS>
    <maxConcurrentWrites>2</maxConcurrentWrites>
    <disableFsync>false</disableFsync>
    <blockPullOrder>standard</blockPullOrder>
    <copyRangeMethod>standard</copyRangeMethod>
    <caseSensitiveFS>false</caseSensitiveFS>
    <junctionsAsDirs>false</junctionsAsDirs>
</folder>

One or more folder elements must be present in the file. Each element describes one folder. The following attributes may be set on the folder element:

id (mandatory)¶: The folder ID, which must be unique.

label¶: The label of a folder is a human readable and descriptive local name. May be different on each device, empty, and/or identical to other folder labels. (optional)

filesystemType¶: The internal file system implementation used to access this folder, detailed in a separate chapter.

path (mandatory)¶: The path to the directory where the folder is stored on this device; not sent to other devices.

type¶

Controls how the folder is handled by Syncthing. Possible values are:

sendreceive: The folder is in default mode. Sending local and accepting remote changes. Note that this type was previously called “readwrite” which is deprecated but still accepted in incoming configs.
sendonly: The folder is in “send only” mode – it will not be modified by Syncthing on this device. Note that this type was previously called “readonly” which is deprecated but still accepted in incoming configs.
receiveonly: The folder is in “receive only” mode – it will not propagate changes to other devices.
receiveencrypted: Must be used on untrusted devices, where the data cannot be decrypted because no folder password was entered. See Untrusted (Encrypted) Devices.

rescanIntervalS¶: The rescan interval, in seconds. Can be set to 0 to disable when external plugins are used to trigger rescans.

fsWatcherEnabled¶: If set to true, this detects changes to files in the folder and scans them.

fsWatcherDelayS¶: The duration during which changes detected are accumulated, before a scan is scheduled (only takes effect if fsWatcherEnabled is set to true).

ignorePerms¶: If true, files originating from this folder will be announced to remote devices with the “no permission bits” flag. The remote devices will use whatever their default permission setting is when creating the files. The primary use case is for file systems that do not support permissions, such as FAT, or environments where changing permissions is impossible.

autoNormalize¶: Automatically correct UTF-8 normalization errors found in file names. The mechanism and how to set it up is described in a separate chapter.

The following child elements may exist:

device¶

These must have the id attribute and can have an introducedBy attribute, identifying the device that introduced us to share this folder with the given device. If the original introducer unshares this folder with this device, our device will follow and unshare the folder (subject to skipIntroductionRemovals being false on the introducer device).

All mentioned devices are those that will be sharing the folder in question. Each mentioned device must have a separate device element later in the file. It is customary that the local device ID is included in all folders. Syncthing will currently add this automatically if it is not present in the configuration file.

The encryptionPassword sub-element contains the secret needed to decrypt this folder’s data on the remote device. If left empty, the data is plainly accessible (but still protected by the transport encryption). The mechanism and how to set it up is described in a separate chapter.

minDiskFree¶: The minimum required free space that should be available on the disk this folder resides. The folder will be stopped when the value drops below the threshold. The element content is interpreted according to the given unit attribute. Accepted unit values are % (percent of the disk / volume size), kB, MB, GB and TB. Set to zero to disable.

versioning¶: Specifies a versioning configuration.

See also

File Versioning

copiers¶
hashers¶: The number of copier and hasher routines to use, or 0 for the system determined optimums. These are low-level performance options for advanced users only; do not change unless requested to or you’ve actually read and understood the code yourself. :)

pullerMaxPendingKiB¶: Controls when we stop sending requests to other devices once we’ve got this much unserved requests. The number of pullers is automatically adjusted based on this desired amount of outstanding request data.

order¶

The order in which needed files should be pulled from the cluster. It has no effect when the folder type is “send only”. The possibles values are:

random (default): Pull files in random order. This optimizes for balancing resources among the devices in a cluster.
alphabetic: Pull files ordered by file name alphabetically.
smallestFirst, largestFirst: Pull files ordered by file size; smallest and largest first respectively.
oldestFirst, newestFirst: Pull files ordered by modification time; oldest and newest first respectively.

Note that the scanned files are sent in batches and the sorting is applied only to the already discovered files. This means the sync might start with a 1 GB file even if there is 1 KB file available on the source device until the 1 KB becomes known to the pulling device.

ignoreDelete¶: Warning

Enabling this is highly discouraged - use at your own risk. You have been warned.

When set to true, this device will pretend not to see instructions to delete files from other devices. The mechanism is described in a separate chapter.

scanProgressIntervalS¶: The interval in seconds with which scan progress information is sent to the GUI. Setting to 0 will cause Syncthing to use the default value of two.

pullerPauseS¶: Tweak for rate limiting the puller when it retries pulling files. Don’t change this unless you know what you’re doing.

maxConflicts¶: The maximum number of conflict copies to keep around for any given file. The default, -1, means an unlimited number. Setting this to 0 disables conflict copies altogether.

disableSparseFiles¶: By default, blocks containing all zeros are not written, causing files to be sparse on filesystems that support this feature. When set to true, sparse files will not be created.

disableTempIndexes¶: By default, devices exchange information about blocks available in transfers that are still in progress, which allows other devices to download parts of files that are not yet fully downloaded on your own device, essentially making transfers more torrent like. When set to true, such information is not exchanged for this folder.

paused¶: True if this folder is (temporarily) suspended.

weakHashThresholdPct¶: Use weak hash if more than the given percentage of the file has changed. Set to -1 to always use weak hash. Default is 25.

markerName¶: Name of a directory or file in the folder root to be used as How do I serve a folder from a read only filesystem?. Default is .stfolder.

copyOwnershipFromParent¶: On Unix systems, tries to copy file/folder ownership from the parent directory (the directory it’s located in). Requires running Syncthing as a privileged user, or granting it additional capabilities (e.g. CAP_CHOWN on Linux).

modTimeWindowS¶: Allowed modification timestamp difference when comparing files for equivalence. To be used on file systems which have unstable modification timestamps that might change after being recorded during the last write operation. Default is 2 on Android when the folder is located on a FAT partition, and 0 otherwise.

maxConcurrentWrites¶: Maximum number of concurrent write operations while syncing. Increasing this might increase or decrease disk performance, depending on the underlying storage. Default is 2.

disableFsync¶: Warning

This is a known insecure option - use at your own risk.

Disables committing file operations to disk before recording them in the database. Disabling fsync can lead to data corruption. The mechanism is described in a separate chapter.

blockPullOrder¶

Order in which the blocks of a file are downloaded. This option controls how quickly different parts of the file spread between the connected devices, at the cost of causing strain on the storage.

Available options:

standard (default): The blocks of a file are split into N equal continuous sequences, where N is the number of connected devices. Each device starts downloading its own sequence, after which it picks other devices sequences at random. Provides acceptable data distribution and minimal spinning disk strain.
random: The blocks of a file are downloaded in a random order. Provides great data distribution, but very taxing on spinning disk drives.
inOrder: The blocks of a file are downloaded sequentially, from start to finish. Spinning disk drive friendly, but provides no improvements to data distribution.

copyRangeMethod¶: Provides a choice of method for copying data between files. This can be used to optimise copies on network filesystems, improve speed of large copies or clone the data using copy-on-write functionality if the underlying filesystem supports it. The mechanism is described in a separate chapter.

caseSensitiveFS¶: Affects performance by disabling the extra safety checks for case insensitive filesystems. The mechanism and how to set it up is described in a separate chapter.

junctionsAsDirs¶: NTFS directory junctions are treated as ordinary directories, if this is set to true.

Device Element¶

<device id="S7UKX27-GI7ZTXS-GC6RKUA-7AJGZ44-C6NAYEB-HSKTJQK-KJHU2NO-CWV7EQW" name="syno" compression="metadata" introducer="false" skipIntroductionRemovals="false" introducedBy="2CYF2WQ-AKZO2QZ-JAKWLYD-AGHMQUM-BGXUOIS-GYILW34-HJG3DUK-LRRYQAR">
    <address>dynamic</address>
    <paused>false</paused>
    <autoAcceptFolders>false</autoAcceptFolders>
    <maxSendKbps>0</maxSendKbps>
    <maxRecvKbps>0</maxRecvKbps>
    <ignoredFolder time="2022-01-09T19:09:52Z" id="br63e-wyhb7" label="Foo"></ignoredFolder>
    <maxRequestKiB>0</maxRequestKiB>
    <untrusted>false</untrusted>
    <remoteGUIPort>0</remoteGUIPort>
</device>
<device id="2CYF2WQ-AKZO2QZ-JAKWLYD-AGHMQUM-BGXUOIS-GYILW34-HJG3DUK-LRRYQAR" name="syno local" compression="metadata" introducer="true" skipIntroductionRemovals="false" introducedBy="">
    <address>tcp://192.0.2.1:22001</address>
    <paused>true</paused>
    <allowedNetwork>192.168.0.0/16</allowedNetwork>
    <autoAcceptFolders>false</autoAcceptFolders>
    <maxSendKbps>100</maxSendKbps>
    <maxRecvKbps>100</maxRecvKbps>
    <maxRequestKiB>65536</maxRequestKiB>
    <untrusted>false</untrusted>
    <remoteGUIPort>8384</remoteGUIPort>
</device>

One or more device elements must be present in the file. Each element describes a device participating in the cluster. It is customary to include a device element for the local device; Syncthing will currently add one if it is not present. The following attributes may be set on the device element:

id (mandatory)¶: The device ID.

name¶: A friendly name for the device. (optional)

compression¶

Whether to use protocol compression when sending messages to this device. The possible values are:

metadata: Compress metadata packets, such as index information. Metadata is usually very compression friendly so this is a good default.
always: Compress all packets, including file data. This is recommended if the folders contents are mainly compressible data such as documents or text files.
never: Disable all compression.

introducer¶: Set to true if this device should be trusted as an introducer, i.e. we should copy their list of devices per folder when connecting.

See also

Introducer Configuration

skipIntroductionRemovals¶: Set to true if you wish to follow only introductions and not de-introductions. For example, if this is set, we would not remove a device that we were introduced to even if the original introducer is no longer listing the remote device as known.

introducedBy¶: Defines which device has introduced us to this device. Used only for following de-introductions.

certName¶: The device certificate’s common name, if it is not the default “syncthing”.

From the following child elements at least one address child must exist.

address (mandatory: At least one must be present.)¶

Contains an address or host name to use when attempting to connect to this device. Entries other than dynamic need a protocol specific prefix. For the TCP protocol the prefixes tcp:// (dual-stack), tcp4:// (IPv4 only) or tcp6:// (IPv6 only) can be used. The prefixes for the QUIC protocol are analogous: quic://, quic4:// and quic6:// Note that IP addresses need not use IPv4 or IPv6 prefixes; these are optional. Accepted formats are:

IPv4 address (tcp://192.0.2.42): The default port (22000) is used.
IPv4 address and port (tcp://192.0.2.42:12345): The address and port is used as given.
IPv6 address (tcp://[2001:db8::23:42]): The default port (22000) is used. The address must be enclosed in square brackets.
IPv6 address and port (tcp://[2001:db8::23:42]:12345): The address and port is used as given. The address must be enclosed in square brackets.
Host name (tcp6://fileserver): The host name will be used on the default port (22000) and connections will be attempted only via IPv6.
Host name and port (tcp://fileserver:12345): The host name will be used on the given port and connections will be attempted via both IPv4 and IPv6, depending on name resolution.
dynamic: The word dynamic (without any prefix) means to use local and global discovery to find the device.

You can set multiple addresses and combine it with the dynamic keyword for example:

<device id="...">
    <address>tcp://192.0.2.1:22001</address>
    <address>quic://192.0.1.254:22000</address>
    <address>dynamic</address>
</device>

paused¶: True if synchronization with this devices is (temporarily) suspended.

allowedNetwork¶: If given, this restricts connections to this device to only this network. The mechanism is described in detail in a separate chapter).

autoAcceptFolders¶: If true, folders shared from this remote device are automatically added and synced locally under the default path. For the folder name, Syncthing tries to use the label from the remote device, and if the same label already exists, it then tries to use the folder’s ID. If that exists as well, the folder is just offered to accept manually. A local folder already added with the same ID will just be shared rather than created separately.

maxSendKbps¶: Maximum send rate to use for this device. Unit is kibibytes/second, despite the config name looking like kilobits/second.

maxRecvKbps¶: Maximum receive rate to use for this device. Unit is kibibytes/second, despite the config name looking like kilobits/second.

ignoredFolder¶: Contains the ID of the folder that should be ignored. This folder will always be skipped when advertised from the containing remote device, i.e. this will be logged, but there will be no dialog shown in the web GUI.

maxRequestKiB¶: Maximum amount of data to have outstanding in requests towards this device. Unit is kibibytes.

remoteGUIPort¶: If set to a positive integer, the GUI will display an HTTP link to the IP address which is currently used for synchronization. Only the TCP port is exchanged for the value specified here. Note that any port forwarding or firewall settings need to be done manually and the link will probably not work for link-local IPv6 addresses because of modern browser limitations.

untrusted¶: This boolean value marks a particular device as untrusted, which disallows ever sharing any unencrypted data with it. Every folder shared with that device then needs an encryption password set, or must already be of the “receive encrypted” type locally. Refer to the detailed explanation under Untrusted (Encrypted) Devices.

GUI Element¶

<gui enabled="true" tls="false" debugging="false">
    <address>127.0.0.1:8384</address>
    <apikey>k1dnz1Dd0rzTBjjFFh7CXPnrF12C49B1</apikey>
    <theme>default</theme>
</gui>

There must be exactly one gui element. The GUI configuration is also used by the REST API and the Event API. The following attributes may be set on the gui element:

enabled¶: If not true, the GUI and API will not be started.

tls¶: If set to true, TLS (HTTPS) will be enforced. Non-HTTPS requests will be redirected to HTTPS. When set to false, TLS connections are still possible but not required.

debugging¶: This enables Profiling and additional endpoints in the REST API, see Debug Endpoints.

The following child elements may be present:

address (mandatory: Exactly one element must be present.)¶

Set the listen address. Allowed address formats are:

IPv4 address and port (127.0.0.1:8384): The address and port are used as given.
IPv6 address and port ([::1]:8384): The address and port are used as given. The address must be enclosed in square brackets.
Wildcard and port (0.0.0.0:12345, [::]:12345, :12345): These are equivalent and will result in Syncthing listening on all interfaces via both IPv4 and IPv6.
UNIX socket location (/var/run/st.sock): If the address is an absolute path it is interpreted as the path to a UNIX socket.

unixSocketPermissions¶: When address is set to a UNIX socket location, set this to an octal value to override the default permissions of the socket.

user¶: Set to require authentication.

password¶: Contains the bcrypt hash of the real password.

apikey¶: If set, this is the API key that enables usage of the REST interface.

insecureAdminAccess¶: If true, this allows access to the web GUI from outside (i.e. not localhost) without authorization. A warning will displayed about this setting on startup.

insecureSkipHostcheck¶: When the GUI / API is bound to localhost, we enforce that the Host header looks like localhost. This option bypasses that check.

insecureAllowFrameLoading¶: Allow rendering the GUI within an <iframe>, <frame> or <object> by not setting the X-Frame-Options: SAMEORIGIN HTTP header. This may be needed for serving the Syncthing GUI as part of a website through a proxy.

theme¶: The name of the theme to use.

authMode¶

Authentication mode to use. If not present, the authentication mode (static) is controlled by the presence of user/password fields for backward compatibility.

static: Authentication using user and password.
ldap: LDAP authentication. Requires ldap top level config section to be present.

LDAP Element¶

<ldap>
    <address>localhost:389</address>
    <bindDN>cn=%s,ou=users,dc=syncthing,dc=net</bindDN>
    <transport>nontls</transport>
    <insecureSkipVerify>false</insecureSkipVerify>
</ldap>

The ldap element contains LDAP configuration options. The mechanism is described in detail under LDAP Authentication.

address (mandatory)¶: LDAP server address (server:port).

bindDN (mandatory)¶: BindDN for user authentication. Special %s variable should be used to pass username to LDAP.

transport¶

nontls: Non secure connection.
tls: TLS secured connection.
starttls: StartTLS connection mode.

insecureSkipVerify¶: Skip verification (true or false).

searchBaseDN¶: Base DN for user searches.

searchFilter¶: Search filter for user searches.

Options Element¶

<options>
    <listenAddress>default</listenAddress>
    <globalAnnounceServer>default</globalAnnounceServer>
    <globalAnnounceEnabled>true</globalAnnounceEnabled>
    <localAnnounceEnabled>true</localAnnounceEnabled>
    <localAnnouncePort>21027</localAnnouncePort>
    <localAnnounceMCAddr>[ff12::8384]:21027</localAnnounceMCAddr>
    <maxSendKbps>0</maxSendKbps>
    <maxRecvKbps>0</maxRecvKbps>
    <reconnectionIntervalS>60</reconnectionIntervalS>
    <relaysEnabled>true</relaysEnabled>
    <relayReconnectIntervalM>10</relayReconnectIntervalM>
    <startBrowser>true</startBrowser>
    <natEnabled>true</natEnabled>
    <natLeaseMinutes>60</natLeaseMinutes>
    <natRenewalMinutes>30</natRenewalMinutes>
    <natTimeoutSeconds>10</natTimeoutSeconds>
    <urAccepted>0</urAccepted>
    <urSeen>0</urSeen>
    <urUniqueID></urUniqueID>
    <urURL>https://data.syncthing.net/newdata</urURL>
    <urPostInsecurely>false</urPostInsecurely>
    <urInitialDelayS>1800</urInitialDelayS>
    <restartOnWakeup>true</restartOnWakeup>
    <autoUpgradeIntervalH>12</autoUpgradeIntervalH>
    <upgradeToPreReleases>false</upgradeToPreReleases>
    <keepTemporariesH>24</keepTemporariesH>
    <cacheIgnoredFiles>false</cacheIgnoredFiles>
    <progressUpdateIntervalS>5</progressUpdateIntervalS>
    <limitBandwidthInLan>false</limitBandwidthInLan>
    <minHomeDiskFree unit="%">1</minHomeDiskFree>
    <releasesURL>https://upgrades.syncthing.net/meta.json</releasesURL>
    <overwriteRemoteDeviceNamesOnConnect>false</overwriteRemoteDeviceNamesOnConnect>
    <tempIndexMinBlocks>10</tempIndexMinBlocks>
    <unackedNotificationID>authenticationUserAndPassword</unackedNotificationID>
    <trafficClass>0</trafficClass>
    <setLowPriority>true</setLowPriority>
    <maxFolderConcurrency>0</maxFolderConcurrency>
    <crashReportingURL>https://crash.syncthing.net/newcrash</crashReportingURL>
    <crashReportingEnabled>true</crashReportingEnabled>
    <stunKeepaliveStartS>180</stunKeepaliveStartS>
    <stunKeepaliveMinS>20</stunKeepaliveMinS>
    <stunServer>default</stunServer>
    <databaseTuning>auto</databaseTuning>
    <maxConcurrentIncomingRequestKiB>0</maxConcurrentIncomingRequestKiB>
    <announceLANAddresses>true</announceLANAddresses>
    <sendFullIndexOnUpgrade>false</sendFullIndexOnUpgrade>
    <connectionLimitEnough>0</connectionLimitEnough>
    <connectionLimitMax>0</connectionLimitMax>
    <insecureAllowOldTLSVersions>false</insecureAllowOldTLSVersions>
</options>

The options element contains all other global configuration options.

listenAddress¶: The listen address for incoming sync connections. See Listen Addresses for the allowed syntax.

globalAnnounceServer¶: A URI to a global announce (discovery) server, or the word default to include the default servers. Any number of globalAnnounceServer elements may be present. The syntax for non-default entries is that of an HTTP or HTTPS URL. A number of options may be added as query options to the URL: insecure to prevent certificate validation (required for HTTP URLs) and id=<device ID> to perform certificate pinning. The device ID to use is printed by the discovery server on startup.

globalAnnounceEnabled¶: Whether to announce this device to the global announce (discovery) server, and also use it to look up other devices.

localAnnounceEnabled¶: Whether to send announcements to the local LAN, also use such announcements to find other devices.

localAnnouncePort¶: The port on which to listen and send IPv4 broadcast announcements to.

localAnnounceMCAddr¶: The group address and port to join and send IPv6 multicast announcements on.

maxSendKbps¶: Outgoing data rate limit, in kibibytes per second.

maxRecvKbps¶: Incoming data rate limits, in kibibytes per second.

reconnectionIntervalS¶: The number of seconds to wait between each attempt to connect to currently unconnected devices.

relaysEnabled¶: When true, relays will be connected to and potentially used for device to device connections.

relayReconnectIntervalM¶: Sets the interval, in minutes, between relay reconnect attempts.

startBrowser¶: Whether to attempt to start a browser to show the GUI when Syncthing starts.

natEnabled¶: Whether to attempt to perform a UPnP and NAT-PMP port mapping for incoming sync connections.

natLeaseMinutes¶: Request a lease for this many minutes; zero to request a permanent lease.

natRenewalMinutes¶: Attempt to renew the lease after this many minutes.

natTimeoutSeconds¶: When scanning for UPnP devices, wait this long for responses.

urAccepted¶: Whether the user has accepted to submit anonymous usage data. The default, 0, mean the user has not made a choice, and Syncthing will ask at some point in the future. -1 means no, a number above zero means that that version of usage reporting has been accepted.

urSeen¶: The highest usage reporting version that has already been shown in the web GUI.

urUniqueID¶: The unique ID sent together with the usage report. Generated when usage reporting is enabled.

urURL¶: The URL to post usage report data to, when enabled.

urPostInsecurely¶: When true, the UR URL can be http instead of https, or have a self-signed certificate. The default is false.

urInitialDelayS¶: The time to wait from startup for the first usage report to be sent. Allows the system to stabilize before reporting statistics.

restartOnWakeup¶: Whether to perform a restart of Syncthing when it is detected that we are waking from sleep mode (i.e. an unfolding laptop).

autoUpgradeIntervalH¶: Check for a newer version after this many hours. Set to 0 to disable automatic upgrades.

upgradeToPreReleases¶: If true, automatic upgrades include release candidates (see Versions & Releases).

keepTemporariesH¶: Keep temporary failed transfers for this many hours. While the temporaries are kept, the data they contain need not be transferred again.

cacheIgnoredFiles¶: Whether to cache the results of ignore pattern evaluation. Performance at the price of memory. Defaults to false as the cost for evaluating ignores is usually not significant.

progressUpdateIntervalS¶: How often in seconds the progress of ongoing downloads is made available to the GUI.

limitBandwidthInLan¶: Whether to apply bandwidth limits to devices in the same broadcast domain as the local device.

minHomeDiskFree¶: The minimum required free space that should be available on the partition holding the configuration and index. The element content is interpreted according to the given unit attribute. Accepted unit values are % (percent of the disk / volume size), kB, MB, GB and TB. Set to zero to disable.

releasesURL¶: The URL from which release information is loaded, for automatic upgrades.

alwaysLocalNet¶: Network that should be considered as local given in CIDR notation.

overwriteRemoteDeviceNamesOnConnect¶: If set, device names will always be overwritten with the name given by remote on each connection. By default, the name that the remote device announces will only be adopted when a name has not already been set.

tempIndexMinBlocks¶: When exchanging index information for incomplete transfers, only take into account files that have at least this many blocks.

unackedNotificationID¶: ID of a notification to be displayed in the web GUI. Will be removed once the user acknowledged it (e.g. an transition notice on an upgrade).

trafficClass¶: Specify a type of service (TOS)/traffic class of outgoing packets.

stunServer¶: Server to be used for STUN, given as ip:port. The keyword default gets expanded to stun.callwithus.com:3478, stun.counterpath.com:3478, stun.counterpath.net:3478, stun.ekiga.net:3478, stun.ideasip.com:3478, stun.internetcalls.com:3478, stun.schlund.de:3478, stun.sipgate.net:10000, stun.sipgate.net:3478, stun.voip.aebc.com:3478, stun.voiparound.com:3478, stun.voipbuster.com:3478, stun.voipstunt.com:3478 and stun.xten.com:3478 (this is the default).

stunKeepaliveStartS¶: Interval in seconds between contacting a STUN server to maintain NAT mapping. Default is 24 and you can set it to 0 to disable contacting STUN servers. The interval is automatically reduced if needed, down to a minimum of stunKeepaliveMinS.

stunKeepaliveMinS¶: Minimum for the stunKeepaliveStartS interval, in seconds.

setLowPriority¶: Syncthing will attempt to lower its process priority at startup. Specifically: on Linux, set itself to a separate process group, set the niceness level of that process group to nine and the I/O priority to best effort level five; on other Unixes, set the process niceness level to nine; on Windows, set the process priority class to below normal. To disable this behavior, for example to control process priority yourself as part of launching Syncthing, set this option to false.

maxFolderConcurrency¶: This option controls how many folders may concurrently be in I/O-intensive operations such as syncing or scanning. The mechanism is described in detail in a separate chapter.

crashReportingURL¶: Server URL where automatic crash reports will be sent if enabled.

crashReportingEnabled¶: Switch to opt out from the automatic crash reporting feature. Set false to keep Syncthing from sending panic logs on serious troubles. Defaults to true, to help the developers troubleshoot.

databaseTuning¶: Controls how Syncthing uses the backend key-value database that stores the index data and other persistent data it needs. The available options and implications are explained in a separate chapter.

maxConcurrentIncomingRequestKiB¶: This limits how many bytes we have “in the air” in the form of response data being read and processed.

announceLANAddresses¶: Enable (the default) or disable announcing private (RFC1918) LAN IP addresses to global discovery.

sendFullIndexOnUpgrade¶: Controls whether all index data is resent when an upgrade has happened, equivalent to starting Syncthing with --reset-deltas. This used to be the default behavior in older versions, but is mainly useful as a troubleshooting step and causes high database churn. The default is now false.

featureFlag¶: Feature flags are simple strings that, when added to the configuration, may unleash unfinished or still-in-development features to allow early user testing. Any supported value will be separately announced with the feature, so that regular users do not enable it by accident.

connectionLimitEnough¶: The number of connections at which we stop trying to connect to more devices, zero meaning no limit. Does not affect incoming connections. The mechanism is described in detail in a separate chapter.

connectionLimitMax¶: The maximum number of connections which we will allow in total, zero meaning no limit. Affects incoming connections and prevents attempting outgoing connections. The mechanism is described in detail in a separate chapter.

insecureAllowOldTLSVersions¶: Only for compatibility with old versions of Syncthing on remote devices, as detailed in insecureAllowOldTLSVersions.

Defaults Element¶

<defaults>
    <folder id="" label="" path="~" type="sendreceive" rescanIntervalS="3600" fsWatcherEnabled="true" fsWatcherDelayS="10" ignorePerms="false" autoNormalize="true">
        <filesystemType>basic</filesystemType>
        <device id="S7UKX27-GI7ZTXS-GC6RKUA-7AJGZ44-C6NAYEB-HSKTJQK-KJHU2NO-CWV7EQW" introducedBy="">
            <encryptionPassword></encryptionPassword>
        </device>
        <minDiskFree unit="%">1</minDiskFree>
        <versioning>
            <cleanupIntervalS>3600</cleanupIntervalS>
            <fsPath></fsPath>
            <fsType>basic</fsType>
        </versioning>
        <copiers>0</copiers>
        <pullerMaxPendingKiB>0</pullerMaxPendingKiB>
        <hashers>0</hashers>
        <order>random</order>
        <ignoreDelete>false</ignoreDelete>
        <scanProgressIntervalS>0</scanProgressIntervalS>
        <pullerPauseS>0</pullerPauseS>
        <maxConflicts>10</maxConflicts>
        <disableSparseFiles>false</disableSparseFiles>
        <disableTempIndexes>false</disableTempIndexes>
        <paused>false</paused>
        <weakHashThresholdPct>25</weakHashThresholdPct>
        <markerName>.stfolder</markerName>
        <copyOwnershipFromParent>false</copyOwnershipFromParent>
        <modTimeWindowS>0</modTimeWindowS>
        <maxConcurrentWrites>2</maxConcurrentWrites>
        <disableFsync>false</disableFsync>
        <blockPullOrder>standard</blockPullOrder>
        <copyRangeMethod>standard</copyRangeMethod>
        <caseSensitiveFS>false</caseSensitiveFS>
        <junctionsAsDirs>false</junctionsAsDirs>
    </folder>
    <device id="" compression="metadata" introducer="false" skipIntroductionRemovals="false" introducedBy="">
        <address>dynamic</address>
        <paused>false</paused>
        <autoAcceptFolders>false</autoAcceptFolders>
        <maxSendKbps>0</maxSendKbps>
        <maxRecvKbps>0</maxRecvKbps>
        <maxRequestKiB>0</maxRequestKiB>
        <untrusted>false</untrusted>
        <remoteGUIPort>0</remoteGUIPort>
    </device>
</defaults>

The defaults element describes a template for newly added device and folder options. These will be used when adding a new remote device or folder, either through the GUI or the command line interface. The following child elements can be present in the defaults element:

device¶: Template for a device element, with the same internal structure. Any fields here will be used for a newly added remote device. The id attribute is meaningless in this context.

folder¶

Template for a folder element, with the same internal structure. Any fields here will be used for a newly added shared folder. The id attribute is meaningless in this context.

The UI will propose to create new folders at the path given in the path attribute (used to be defaultFolderPath under options). It also applies to folders automatically accepted from a remote device.

Even sharing with other remote devices can be done in the template by including the appropriate folder.device element underneath.

Listen Addresses¶

The following address types are accepted in sync protocol listen addresses. If you want Syncthing to listen on multiple addresses, you can either: add multiple <listenAddress> tags in the configuration file or enter several addresses separated by commas in the GUI.

Default listen addresses (default): This is equivalent to tcp://0.0.0.0:22000, quic://0.0.0.0:22000 and dynamic+https://relays.syncthing.net/endpoint.
TCP wildcard and port (tcp://0.0.0.0:22000, tcp://:22000): These are equivalent and will result in Syncthing listening on all interfaces, IPv4 and IPv6, on the specified port.
TCP IPv4 wildcard and port (tcp4://0.0.0.0:22000, tcp4://:22000): These are equivalent and will result in Syncthing listening on all interfaces via IPv4 only.
TCP IPv4 address and port (tcp4://192.0.2.1:22000): This results in Syncthing listening on the specified address and port, IPv4 only.
TCP IPv6 wildcard and port (tcp6://[::]:22000, tcp6://:22000): These are equivalent and will result in Syncthing listening on all interfaces via IPv6 only.
TCP IPv6 address and port (tcp6://[2001:db8::42]:22000): This results in Syncthing listening on the specified address and port, IPv6 only.
QUIC address and port (e.g. quic://0.0.0.0:22000): Syntax is the same as for TCP, also quic4 and quic6 can be used.
Static relay address (relay://192.0.2.42:22067?id=abcd123...): Syncthing will connect to and listen for incoming connections via the specified relay address.

Todo

Document available URL parameters.
Dynamic relay pool (dynamic+https://192.0.2.42/relays): Syncthing will fetch the specified HTTPS URL, parse it for a JSON payload describing relays, select a relay from the available ones and listen via that as if specified as a static relay above.

Todo

Document available URL parameters.

Syncing Configuration Files¶

Syncing configuration files between devices (such that multiple devices are using the same configuration files) can cause issues. This is easy to do accidentally if you sync your home folder between devices. A common symptom of syncing configuration files is two devices ending up with the same Device ID.

If you want to use Syncthing to backup your configuration files, it is recommended that the files you are backing up are in a Send Only Folder to prevent other devices from overwriting the per device configuration. The folder on the remote device(s) should not be used as configuration for the remote devices.

If you’d like to sync your home folder in non-send only mode, you may add the folder that stores the configuration files to the ignore list. If you’d also like to backup your configuration files, add another folder in send only mode for just the configuration folder.