Syncthing Configuration

Synopsis

$HOME/.config/syncthing
$HOME/Library/Application Support/Syncthing
%AppData%/Syncthing
%localappdata%/Syncthing

Description

Syncthing uses a single directory to store configuration, crypto keys and index caches. The location defaults to $HOME/.config/syncthing (Unix-like), $HOME/Library/Application Support/Syncthing (Mac), %AppData%/Syncthing (Windows XP) or %LocalAppData%/Syncthing (Windows 7+). It can be changed at runtime using the -home flag. In this directory the following files are located:

config.xml
The configuration file, in XML format.
cert.pem, key.pem
The device’s RSA 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.
index-*.db
A directory holding the database with metadata and hashes of the files currently on disk and available from peers.
csrftokens.txt
A list of recently issued CSRF tokens (for protection against browser cross site request forgery).

Config File Format

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

<configuration version="14">
    <folder id="zj2AA-q55a7" label="Default Folder (zj2AA-q55a7)" path="/Users/jb/Sync/" type="readwrite" rescanIntervalS="60" ignorePerms="false" autoNormalize="true">
        <device id="3LT2GA5-CQI4XJM-WTZ264P-MLOGMHL-MCRLDNT-MZV4RD3-KA745CL-OGAERQZ"></device>
        <minDiskFree unit="%">1</minDiskFree>
        <versioning></versioning>
        <copiers>0</copiers>
        <pullers>0</pullers>
        <hashers>0</hashers>
        <order>random</order>
        <ignoreDelete>false</ignoreDelete>
        <scanProgressIntervalS>0</scanProgressIntervalS>
        <pullerSleepS>0</pullerSleepS>
        <pullerPauseS>0</pullerPauseS>
        <maxConflicts>-1</maxConflicts>
        <disableSparseFiles>false</disableSparseFiles>
        <disableTempIndexes>false</disableTempIndexes>
        <fsync>false</fsync>
    </folder>
    <device id="3LT2GA5-CQI4XJM-WTZ264P-MLOGMHL-MCRLDNT-MZV4RD3-KA745CL-OGAERQZ" name="syno" compression="metadata" introducer="false">
        <address>dynamic</address>
    </device>
    <gui enabled="true" tls="false">
        <address>127.0.0.1:8384</address>
        <apikey>k1dnz1Dd0rzTBjjFFh7CXPnrF12C49B1</apikey>
        <theme>default</theme>
    </gui>
    <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>
        <urUniqueID></urUniqueID>
        <urURL>https://data.syncthing.net/newdata</urURL>
        <urPostInsecurely>false</urPostInsecurely>
        <urInitialDelayS>1800</urInitialDelayS>
        <restartOnWakeup>true</restartOnWakeup>
        <autoUpgradeIntervalH>12</autoUpgradeIntervalH>
        <keepTemporariesH>24</keepTemporariesH>
        <cacheIgnoredFiles>false</cacheIgnoredFiles>
        <progressUpdateIntervalS>5</progressUpdateIntervalS>
        <limitBandwidthInLan>false</limitBandwidthInLan>
        <minHomeDiskFree unit="%">1</minHomeDiskFree>
        <releasesURL>https://api.github.com/repos/syncthing/syncthing/releases?per_page=30</releasesURL>
        <overwriteRemoteDeviceNamesOnConnect>false</overwriteRemoteDeviceNamesOnConnect>
        <tempIndexMinBlocks>10</tempIndexMinBlocks>
        <defaultFolderPath>~</defaultFolderPath>
    </options>
</configuration>

Configuration Element

This is the root element.

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

Folder Element

<folder id="zj2AA-q55a7" label="Default Folder (zj2AA-q55a7)" path="/Users/jb/Sync/" type="readwrite" rescanIntervalS="60" ignorePerms="false" autoNormalize="true" ro="false">
    <device id="3LT2GA5-CQI4XJM-WTZ264P-MLOGMHL-MCRLDNT-MZV4RD3-KA745CL-OGAERQZ" introducedBy="2CYF2WQ-AKZO2QZ-JAKWLYD-AGHMQUM-BGXUOIS-GYILW34-HJG3DUK-LRRYQAR"></device>
    <minDiskFree unit="%">1</minDiskFree>
    <versioning></versioning>
    <copiers>0</copiers>
    <pullers>0</pullers>
    <hashers>0</hashers>
    <order>random</order>
    <ignoreDelete>false</ignoreDelete>
    <scanProgressIntervalS>0</scanProgressIntervalS>
    <pullerSleepS>0</pullerSleepS>
    <pullerPauseS>0</pullerPauseS>
    <maxConflicts>-1</maxConflicts>
    <disableSparseFiles>false</disableSparseFiles>
    <disableTempIndexes>false</disableTempIndexes>
    <fsync>false</fsync>
</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
The folder ID, must be unique. (mandatory)
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)
path
The path to the directory where the folder is stored on this device; not sent to other devices. (mandatory)
type

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

readwrite
The folder is in default mode. Sending local and accepting remote changes.
readonly
The folder is in “send-only” mode – it will not be modified by Syncthing on this device.
rescanIntervalS
The rescan interval, in seconds. Can be set to zero to disable when external plugins are used to trigger rescans.
ignorePerms
True if the folder should ignore permissions.
autoNormalize
Automatically correct UTF-8 normalization errors found in file names.

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.
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. Accepted units are %, kB, MB, GB and TB. Set to zero to disable.
versioning
Specifies a versioning configuration.

See also

File Versioning

copiers, pullers, hashers
The number of copier, puller and hasher routines to use, or zero for the system determined optimum. 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. :)
order

The order in which needed files should be pulled from the cluster. The possibles values are:

random
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.
ignoreDelete
When set to true, this device will pretend not to see instructions to delete files from other devices.
scanProgressIntervalS
The interval with which scan progress information is sent to the GUI. Zero means the default value (two seconds).
pullerSleepS, pullerPauseS
Tweaks for rate limiting the puller. Don’t change these 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 zero disables conflict copies altogether.
disableSparseFiles
By default, blocks containing all zeroes are not written, causing files to be sparse on filesystems that support the concept. 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. When set to true, such information is not exchanged for this folder.
fsync
Transfer updated (from other devices) files to permanent storage before committing the changes to the internal database.

Device Element

<device id="5SYI2FS-LW6YAXI-JJDYETS-NDBBPIO-256MWBO-XDPXWVG-24QPUM4-PDW4UQU" name="syno" compression="metadata" introducer="false" introducedBy="2CYF2WQ-AKZO2QZ-JAKWLYD-AGHMQUM-BGXUOIS-GYILW34-HJG3DUK-LRRYQAR">
    <address>dynamic</address>
</device>
<device id="2CYF2WQ-AKZO2QZ-JAKWLYD-AGHMQUM-BGXUOIS-GYILW34-HJG3DUK-LRRYQAR" name="syno local" compression="metadata" introducer="false">
    <address>tcp://192.0.2.1:22001</address>
</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
The device ID. This must be written in canonical form, that is without any spaces or dashes. (mandatory)
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.
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.

In addition, one or more address child elements must be present. Each contains an address or host name to use when attempting to connect to this device and will be tried in order. Entries other than dynamic must be prefixed with tcp:// (dual-stack), tcp4:// (IPv4 only) or tcp6:// (IPv6 only). Note that IP addresses need not use tcp4/tcp6; 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 tcp:// prefix) means to use local and global discovery to find the device.

IgnoredDevice Element

<ignoredDevice>5SYI2FS-LW6YAXI-JJDYETS-NDBBPIO-256MWBO-XDPXWVG-24QPUM4-PDW4UQU</ignoredDevice>

This optional element lists device IDs that have been specifically ignored. One element must be present for each device ID. Connection attempts from these devices are logged to the console but never displayed in the web GUI.

GUI Element

<gui enabled="true" tls="false">
    <address>127.0.0.1:8384</address>
    <apikey>l7jSbCqPD95JYZ0g8vi4ZLAMg3ulnN1b</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 this is set to false, TLS connections are still possible but it is not mandatory.
theme
The name of the theme to use.

The following child elements may be present:

address

Set the listen address. One address element must be present. Allowed address formats are:

IPv4 address and port (127.0.0.1:8384)
The address and port is used as given.
IPv6 address and port ([::1]:8384)
The address and port is 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.
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.

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>
    <urUniqueID></urUniqueID>
    <urURL>https://data.syncthing.net/newdata</urURL>
    <urPostInsecurely>false</urPostInsecurely>
    <urInitialDelayS>1800</urInitialDelayS>
    <restartOnWakeup>true</restartOnWakeup>
    <autoUpgradeIntervalH>12</autoUpgradeIntervalH>
    <keepTemporariesH>24</keepTemporariesH>
    <cacheIgnoredFiles>false</cacheIgnoredFiles>
    <progressUpdateIntervalS>5</progressUpdateIntervalS>
    <limitBandwidthInLan>false</limitBandwidthInLan>
    <minHomeDiskFree unit="%">1</minHomeDiskFree>
    <releasesURL>https://api.github.com/repos/syncthing/syncthing/releases?per_page=30</releasesURL>
    <overwriteRemoteDeviceNamesOnConnect>false</overwriteRemoteDeviceNamesOnConnect>
    <tempIndexMinBlocks>10</tempIndexMinBlocks>
    <defaultFolderPath>~</defaultFolderPath>
</options>

The options element contains all other global configuration options.

listenAddress
The listen address for incoming sync connections. See Listen Addresses for 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 a 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.
relayServer
Lists one or more relay servers, on the format relay://hostname:port. Alternatively, a relay list can be loaded over https by using an URL like dynamic+https://somehost/path. The default loads the list of relays from the relay pool server, relays.syncthing.net.
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.
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 to the first usage report being 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. a folded up laptop).
autoUpgradeIntervalH
Check for a newer version after this many hours. Set to zero to disable automatic upgrades.
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.
databaseBlockCacheMiB
Override the automatically calculated database block cache size. Don’t, unless you’re very short on memory, in which case you want to set this to 8.
pingTimeoutS
Ping-timeout in seconds. Don’t change it unless you are having issues due to slow response time (slow connection/cpu) and large index exchanges.
pingIdleTimeS
Ping interval in seconds. Don’t change it unless you feel it’s necessary.
minHomeDiskFree
The minimum required free space that should be available on the partition holding the configuration and index. Accepted units are %, kB, MB, GB and TB.
releasesURL
The URL from which release information is loaded, for automatic upgrades.
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.
defaultFolderPath
The UI will propose to create new folders at this path. This can be disabled by setting this to an empty string.

Listen Addresses

The following address types are accepted in sync protocol listen addresses:

Default listen addresses (default)
This is equivalent to tcp://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.
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.