.. -*- coding: utf-8-with-signature -*- ============================= Configuring a Tahoe-LAFS node ============================= 1. `Node Types`_ 2. `Overall Node Configuration`_ 3. `Client Configuration`_ 4. `Storage Server Configuration`_ 5. `Frontend Configuration`_ 6. `Running A Helper`_ 7. `Running An Introducer`_ 8. `Other Files in BASEDIR`_ 9. `Other files`_ 10. `Example`_ A Tahoe-LAFS node is configured by writing to files in its base directory. These files are read by the node when it starts, so each time you change them, you need to restart the node. The node also writes state to its base directory, so it will create files on its own. This document contains a complete list of the config files that are examined by the client node, as well as the state files that you'll observe in its base directory. The main file is named "``tahoe.cfg``", and is an ".INI"-style configuration file (parsed by the Python stdlib 'ConfigParser' module: "``[name]``" section markers, lines with "``key.subkey: value``", rfc822-style continuations). There are also other files containing information that does not easily fit into this format. The "``tahoe create-node``" or "``tahoe create-client``" command will create an initial ``tahoe.cfg`` file for you. After creation, the node will never modify the ``tahoe.cfg`` file: all persistent state is put in other files. The item descriptions below use the following types: ``boolean`` one of (True, yes, on, 1, False, off, no, 0), case-insensitive ``strports string`` a Twisted listening-port specification string, like "``tcp:80``" or "``tcp:3456:interface=127.0.0.1``". For a full description of the format, see `the Twisted strports documentation`_. Please note, if interface= is not specified, Tahoe-LAFS will attempt to bind the port specified on all interfaces. ``FURL string`` a Foolscap endpoint identifier, like ``pb://soklj4y7eok5c3xkmjeqpw@192.168.69.247:44801/eqpwqtzm`` .. _the Twisted strports documentation: https://twistedmatrix.com/documents/current/api/twisted.application.strports.html Node Types ========== A node can be a client/server, an introducer, a statistics gatherer, or a key generator. Client/server nodes provide one or more of the following services: * web-API service * SFTP service * FTP service * drop-upload service * helper service * storage service. A client/server that provides storage service (i.e. storing shares for clients) is called a "storage server". If it provides any of the other services, it is a "storage client" (a node can be both a storage server and a storage client). A client/server node that provides web-API service is called a "gateway". Overall Node Configuration ========================== This section controls the network behavior of the node overall: which ports and IP addresses are used, when connections are timed out, etc. This configuration applies to all node types and is independent of the services that the node is offering. If your node is behind a firewall or NAT device and you want other clients to connect to it, you'll need to open a port in the firewall or NAT, and specify that port number in the tub.port option. If behind a NAT, you *may* need to set the ``tub.location`` option described below. ``[node]`` ``nickname = (UTF-8 string, optional)`` This value will be displayed in management tools as this node's "nickname". If not provided, the nickname will be set to "". This string shall be a UTF-8 encoded Unicode string. ``web.port = (strports string, optional)`` This controls where the node's web server should listen, providing node status and, if the node is a client/server, providing web-API service as defined in webapi.rst_. This file contains a Twisted "strports" specification such as "``3456``" or "``tcp:3456:interface=127.0.0.1``". The "``tahoe create-node``" or "``tahoe create-client``" commands set the ``web.port`` to "``tcp:3456:interface=127.0.0.1``" by default; this is overridable by the ``--webport`` option. You can make it use SSL by writing "``ssl:3456:privateKey=mykey.pem:certKey=cert.pem``" instead. If this is not provided, the node will not run a web server. ``web.static = (string, optional)`` This controls where the ``/static`` portion of the URL space is served. The value is a directory name (``~username`` is allowed, and non-absolute names are interpreted relative to the node's basedir), which can contain HTML and other files. This can be used to serve a Javascript-based frontend to the Tahoe-LAFS node, or other services. The default value is "``public_html``", which will serve ``BASEDIR/public_html`` . With the default settings, ``http://127.0.0.1:3456/static/foo.html`` will serve the contents of ``BASEDIR/public_html/foo.html`` . ``tub.port = (integer, optional)`` This controls which port the node uses to accept Foolscap connections from other nodes. If not provided, the node will ask the kernel for any available port. The port will be written to a separate file (named ``client.port`` or ``introducer.port``), so that subsequent runs will re-use the same port. ``tub.location = (string, optional)`` In addition to running as a client, each Tahoe-LAFS node also runs as a server, listening for connections from other Tahoe-LAFS clients. The node announces its location by publishing a "FURL" (a string with some connection hints) to the Introducer. The string it publishes can be found in ``BASEDIR/private/storage.furl`` . The ``tub.location`` configuration controls what location is published in this announcement. If you don't provide ``tub.location``, the node will try to figure out a useful one by itself, by using tools like "``ifconfig``" to determine the set of IP addresses on which it can be reached from nodes both near and far. It will also include the TCP port number on which it is listening (either the one specified by ``tub.port``, or whichever port was assigned by the kernel when ``tub.port`` is left unspecified). You might want to override this value if your node lives behind a firewall that is doing inbound port forwarding, or if you are using other proxies such that the local IP address or port number is not the same one that remote clients should use to connect. You might also want to control this when using a Tor proxy to avoid revealing your actual IP address through the Introducer announcement. If ``tub.location`` is specified, by default it entirely replaces the automatically determined set of IP addresses. To include the automatically determined addresses as well as the specified ones, include the uppercase string "``AUTO``" in the list. The value is a comma-separated string of host:port location hints, like this:: 123.45.67.89:8098,tahoe.example.com:8098,127.0.0.1:8098 A few examples: * Emulate default behavior, assuming your host has IP address 123.45.67.89 and the kernel-allocated port number was 8098:: tub.port = 8098 tub.location = 123.45.67.89:8098,127.0.0.1:8098 * Use a DNS name so you can change the IP address more easily:: tub.port = 8098 tub.location = tahoe.example.com:8098 * Use a DNS name but also include the default set of addresses:: tub.port = 8098 tub.location = tahoe.example.com:8098,AUTO * Run a node behind a firewall (which has an external IP address) that has been configured to forward port 7912 to our internal node's port 8098:: tub.port = 8098 tub.location = external-firewall.example.com:7912 * Run a node behind a Tor proxy (perhaps via ``torsocks``), in client-only mode (i.e. we can make outbound connections, but other nodes will not be able to connect to us). The literal '``unreachable.example.org``' will not resolve, but will serve as a reminder to human observers that this node cannot be reached. "Don't call us.. we'll call you":: tub.port = 8098 tub.location = unreachable.example.org:0 * Run a node behind a Tor proxy, and make the server available as a Tor "hidden service". (This assumes that other clients are running their node with ``torsocks``, such that they are prepared to connect to a ``.onion`` address.) The hidden service must first be configured in Tor, by giving it a local port number and then obtaining a ``.onion`` name, using something in the ``torrc`` file like:: HiddenServiceDir /var/lib/tor/hidden_services/tahoe HiddenServicePort 29212 127.0.0.1:8098 once Tor is restarted, the ``.onion`` hostname will be in ``/var/lib/tor/hidden_services/tahoe/hostname``. Then set up your ``tahoe.cfg`` like:: tub.port = 8098 tub.location = ualhejtq2p7ohfbb.onion:29212 Most users will not need to set ``tub.location``. ``log_gatherer.furl = (FURL, optional)`` If provided, this contains a single FURL string that is used to contact a "log gatherer", which will be granted access to the logport. This can be used to gather operational logs in a single place. Note that in previous releases of Tahoe-LAFS, if an old-style ``BASEDIR/log_gatherer.furl`` file existed it would also be used in addition to this value, allowing multiple log gatherers to be used at once. As of Tahoe-LAFS v1.9.0, an old-style file is ignored and a warning will be emitted if one is detected. This means that as of Tahoe-LAFS v1.9.0 you can have at most one log gatherer per node. See ticket `#1423`_ about lifting this restriction and letting you have multiple log gatherers. .. _`#1423`: https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1423 ``timeout.keepalive = (integer in seconds, optional)`` ``timeout.disconnect = (integer in seconds, optional)`` If ``timeout.keepalive`` is provided, it is treated as an integral number of seconds, and sets the Foolscap "keepalive timer" to that value. For each connection to another node, if nothing has been heard for a while, we will attempt to provoke the other end into saying something. The duration of silence that passes before sending the PING will be between KT and 2*KT. This is mainly intended to keep NAT boxes from expiring idle TCP sessions, but also gives TCP's long-duration keepalive/disconnect timers some traffic to work with. The default value is 240 (i.e. 4 minutes). If timeout.disconnect is provided, this is treated as an integral number of seconds, and sets the Foolscap "disconnect timer" to that value. For each connection to another node, if nothing has been heard for a while, we will drop the connection. The duration of silence that passes before dropping the connection will be between DT-2*KT and 2*DT+2*KT (please see ticket `#521`_ for more details). If we are sending a large amount of data to the other end (which takes more than DT-2*KT to deliver), we might incorrectly drop the connection. The default behavior (when this value is not provided) is to disable the disconnect timer. See ticket `#521`_ for a discussion of how to pick these timeout values. Using 30 minutes means we'll disconnect after 22 to 68 minutes of inactivity. Receiving data will reset this timeout, however if we have more than 22min of data in the outbound queue (such as 800kB in two pipelined segments of 10 shares each) and the far end has no need to contact us, our ping might be delayed, so we may disconnect them by accident. .. _`#521`: https://tahoe-lafs.org/trac/tahoe-lafs/ticket/521 ``ssh.port = (strports string, optional)`` ``ssh.authorized_keys_file = (filename, optional)`` This enables an SSH-based interactive Python shell, which can be used to inspect the internal state of the node, for debugging. To cause the node to accept SSH connections on port 8022 from the same keys as the rest of your account, use:: [tub] ssh.port = 8022 ssh.authorized_keys_file = ~/.ssh/authorized_keys ``tempdir = (string, optional)`` This specifies a temporary directory for the web-API server to use, for holding large files while they are being uploaded. If a web-API client attempts to upload a 10GB file, this tempdir will need to have at least 10GB available for the upload to complete. The default value is the ``tmp`` directory in the node's base directory (i.e. ``BASEDIR/tmp``), but it can be placed elsewhere. This directory is used for files that usually (on a Unix system) go into ``/tmp``. The string will be interpreted relative to the node's base directory. .. _webapi.rst: frontends/webapi.rst Client Configuration ==================== ``[client]`` ``introducer.furl = (FURL string, mandatory)`` This FURL tells the client how to connect to the introducer. Each Tahoe-LAFS grid is defined by an introducer. The introducer's FURL is created by the introducer node and written into its private base directory when it starts, whereupon it should be published to everyone who wishes to attach a client to that grid ``helper.furl = (FURL string, optional)`` If provided, the node will attempt to connect to and use the given helper for uploads. See helper.rst_ for details. ``key_generator.furl = (FURL string, optional)`` If provided, the node will attempt to connect to and use the given key-generator service, using RSA keys from the external process rather than generating its own. ``stats_gatherer.furl = (FURL string, optional)`` If provided, the node will connect to the given stats gatherer and provide it with operational statistics. ``shares.needed = (int, optional) aka "k", default 3`` ``shares.total = (int, optional) aka "N", N >= k, default 10`` ``shares.happy = (int, optional) 1 <= happy <= N, default 7`` These three values set the default encoding parameters. Each time a new file is uploaded, erasure-coding is used to break the ciphertext into separate shares. There will be ``N`` (i.e. ``shares.total``) shares created, and the file will be recoverable if any ``k`` (i.e. ``shares.needed``) shares are retrieved. The default values are 3-of-10 (i.e. ``shares.needed = 3``, ``shares.total = 10``). Setting ``k`` to 1 is equivalent to simple replication (uploading ``N`` copies of the file). These values control the tradeoff between storage overhead and reliability. To a first approximation, a 1MB file will use (1MB * ``N``/``k``) of backend storage space (the actual value will be a bit more, because of other forms of overhead). Up to ``N``-``k`` shares can be lost before the file becomes unrecoverable. So large ``N``/``k`` ratios are more reliable, and small ``N``/``k`` ratios use less disk space. ``N`` cannot be larger than 256, because of the 8-bit erasure-coding algorithm that Tahoe-LAFS uses. ``k`` can not be greater than ``N``. See performance.rst_ for more details. ``shares.happy`` allows you control over how well to "spread out" the shares of an immutable file. For a successful upload, shares are guaranteed to be initially placed on at least ``shares.happy`` distinct servers, the correct functioning of any ``k`` of which is sufficient to guarantee the availability of the uploaded file. This value should not be larger than the number of servers on your grid. A value of ``shares.happy`` <= ``k`` is allowed, but this is not guaranteed to provide any redundancy if some servers fail or lose shares. It may still provide redundancy in practice if ``N`` is greater than the number of connected servers, because in that case there will typically be more than one share on at least some storage nodes. However, since a successful upload only guarantees that at least ``shares.happy`` shares have been stored, the worst case is still that there is no redundancy. (Mutable files use a different share placement algorithm that does not currently consider this parameter.) ``mutable.format = sdmf or mdmf`` This value tells Tahoe-LAFS what the default mutable file format should be. If ``mutable.format=sdmf``, then newly created mutable files will be in the old SDMF format. This is desirable for clients that operate on grids where some peers run older versions of Tahoe-LAFS, as these older versions cannot read the new MDMF mutable file format. If ``mutable.format`` is ``mdmf``, then newly created mutable files will use the new MDMF format, which supports efficient in-place modification and streaming downloads. You can overwrite this value using a special mutable-type parameter in the webapi. If you do not specify a value here, Tahoe-LAFS will use SDMF for all newly-created mutable files. Note that this parameter applies only to files, not to directories. Mutable directories, which are stored in mutable files, are not controlled by this parameter and will always use SDMF. We may revisit this decision in future versions of Tahoe-LAFS. See mutable.rst_ for details about mutable file formats. .. _helper.rst: helper.rst .. _performance.rst: performance.rst .. _mutable.rst: specifications/mutable.rst Frontend Configuration ====================== The Tahoe client process can run a variety of frontend file-access protocols. You will use these to create and retrieve files from the virtual filesystem. Configuration details for each are documented in the following protocol-specific guides: HTTP Tahoe runs a webserver by default on port 3456. This interface provides a human-oriented "WUI", with pages to create, modify, and browse directories and files, as well as a number of pages to check on the status of your Tahoe node. It also provides a machine-oriented "WAPI", with a REST-ful HTTP interface that can be used by other programs (including the CLI tools). Please see webapi.rst_ for full details, and the ``web.port`` and ``web.static`` config variables above. The `download-status.rst`_ document also describes a few WUI status pages. CLI The main "bin/tahoe" executable includes subcommands for manipulating the filesystem, uploading/downloading files, and creating/running Tahoe nodes. See CLI.rst_ for details. SFTP, FTP Tahoe can also run both SFTP and FTP servers, and map a username/password pair to a top-level Tahoe directory. See FTP-and-SFTP.rst_ for instructions on configuring these services, and the ``[sftpd]`` and ``[ftpd]`` sections of ``tahoe.cfg``. Drop-Upload A node running on Linux or Windows can be configured to automatically upload files that are created or changed in a specified local directory. See `drop-upload.rst`_ for details. .. _download-status.rst: frontends/download-status.rst .. _CLI.rst: frontends/CLI.rst .. _FTP-and-SFTP.rst: frontends/FTP-and-SFTP.rst .. _drop-upload.rst: frontends/drop-upload.rst Storage Server Configuration ============================ ``[storage]`` ``enabled = (boolean, optional)`` If this is ``True``, the node will run a storage server, offering space to other clients. If it is ``False``, the node will not run a storage server, meaning that no shares will be stored on this node. Use ``False`` for clients who do not wish to provide storage service. The default value is ``True``. ``readonly = (boolean, optional)`` If ``True``, the node will run a storage server but will not accept any shares, making it effectively read-only. Use this for storage servers that are being decommissioned: the ``storage/`` directory could be mounted read-only, while shares are moved to other servers. Note that this currently only affects immutable shares. Mutable shares (used for directories) will be written and modified anyway. See ticket `#390`_ for the current status of this bug. The default value is ``False``. ``reserved_space = (str, optional)`` If provided, this value defines how much disk space is reserved: the storage server will not accept any share that causes the amount of free disk space to drop below this value. (The free space is measured by a call to ``statvfs(2)`` on Unix, or ``GetDiskFreeSpaceEx`` on Windows, and is the space available to the user account under which the storage server runs.) This string contains a number, with an optional case-insensitive scale suffix, optionally followed by "B" or "iB". The supported scale suffixes are "K", "M", "G", "T", "P" and "E", and a following "i" indicates to use powers of 1024 rather than 1000. So "100MB", "100 M", "100000000B", "100000000", and "100000kb" all mean the same thing. Likewise, "1MiB", "1024KiB", "1024 Ki", and "1048576 B" all mean the same thing. "``tahoe create-node``" generates a tahoe.cfg with "``reserved_space=1G``", but you may wish to raise, lower, or remove the reservation to suit your needs. ``expire.enabled =`` ``expire.mode =`` ``expire.override_lease_duration =`` ``expire.cutoff_date =`` ``expire.immutable =`` ``expire.mutable =`` These settings control garbage collection, in which the server will delete shares that no longer have an up-to-date lease on them. Please see garbage-collection.rst_ for full details. .. _#390: https://tahoe-lafs.org/trac/tahoe-lafs/ticket/390 .. _garbage-collection.rst: garbage-collection.rst Running A Helper ================ A "helper" is a regular client node that also offers the "upload helper" service. ``[helper]`` ``enabled = (boolean, optional)`` If ``True``, the node will run a helper (see helper.rst_ for details). The helper's contact FURL will be placed in ``private/helper.furl``, from which it can be copied to any clients that wish to use it. Clearly nodes should not both run a helper and attempt to use one: do not create ``helper.furl`` and also define ``[helper]enabled`` in the same node. The default is ``False``. Running An Introducer ===================== The introducer node uses a different ``.tac`` file (named "``introducer.tac``"), and pays attention to the ``[node]`` section, but not the others. The Introducer node maintains some different state than regular client nodes. ``BASEDIR/private/introducer.furl`` This is generated the first time the introducer node is started, and used again on subsequent runs, to give the introduction service a persistent long-term identity. This file should be published and copied into new client nodes before they are started for the first time. Other Files in BASEDIR ====================== Some configuration is not kept in ``tahoe.cfg``, for the following reasons: * it is generated by the node at startup, e.g. encryption keys. The node never writes to ``tahoe.cfg``. * it is generated by user action, e.g. the "``tahoe create-alias``" command. In addition, non-configuration persistent state is kept in the node's base directory, next to the configuration knobs. This section describes these other files. ``private/node.pem`` This contains an SSL private-key certificate. The node generates this the first time it is started, and re-uses it on subsequent runs. This certificate allows the node to have a cryptographically-strong identifier (the Foolscap "TubID"), and to establish secure connections to other nodes. ``storage/`` Nodes that host StorageServers will create this directory to hold shares of files on behalf of other clients. There will be a directory underneath it for each StorageIndex for which this node is holding shares. There is also an "incoming" directory where partially-completed shares are held while they are being received. ``tahoe-client.tac`` This file defines the client, by constructing the actual Client instance each time the node is started. It is used by the "``twistd``" daemonization program (in the ``-y`` mode), which is run internally by the "``tahoe start``" command. This file is created by the "``tahoe create-node``" or "``tahoe create-client``" commands. ``tahoe-introducer.tac`` This file is used to construct an introducer, and is created by the "``tahoe create-introducer``" command. ``tahoe-key-generator.tac`` This file is used to construct a key generator, and is created by the "``tahoe create-key-gernerator``" command. ``tahoe-stats-gatherer.tac`` This file is used to construct a statistics gatherer, and is created by the "``tahoe create-stats-gatherer``" command. ``private/control.furl`` This file contains a FURL that provides access to a control port on the client node, from which files can be uploaded and downloaded. This file is created with permissions that prevent anyone else from reading it (on operating systems that support such a concept), to insure that only the owner of the client node can use this feature. This port is intended for debugging and testing use. ``private/logport.furl`` This file contains a FURL that provides access to a 'log port' on the client node, from which operational logs can be retrieved. Do not grant logport access to strangers, because occasionally secret information may be placed in the logs. ``private/helper.furl`` If the node is running a helper (for use by other clients), its contact FURL will be placed here. See helper.rst_ for more details. ``private/root_dir.cap`` (optional) The command-line tools will read a directory cap out of this file and use it, if you don't specify a '--dir-cap' option or if you specify '--dir-cap=root'. ``private/convergence`` (automatically generated) An added secret for encrypting immutable files. Everyone who has this same string in their ``private/convergence`` file encrypts their immutable files in the same way when uploading them. This causes identical files to "converge" -- to share the same storage space since they have identical ciphertext -- which conserves space and optimizes upload time, but it also exposes file contents to the possibility of a brute-force attack by people who know that string. In this attack, if the attacker can guess most of the contents of a file, then they can use brute-force to learn the remaining contents. So the set of people who know your ``private/convergence`` string is the set of people who converge their storage space with you when you and they upload identical immutable files, and it is also the set of people who could mount such an attack. The content of the ``private/convergence`` file is a base-32 encoded string. If the file doesn't exist, then when the Tahoe-LAFS client starts up it will generate a random 256-bit string and write the base-32 encoding of this string into the file. If you want to converge your immutable files with as many people as possible, put the empty string (so that ``private/convergence`` is a zero-length file). Other files =========== ``logs/`` Each Tahoe-LAFS node creates a directory to hold the log messages produced as the node runs. These logfiles are created and rotated by the "``twistd``" daemonization program, so ``logs/twistd.log`` will contain the most recent messages, ``logs/twistd.log.1`` will contain the previous ones, ``logs/twistd.log.2`` will be older still, and so on. ``twistd`` rotates logfiles after they grow beyond 1MB in size. If the space consumed by logfiles becomes troublesome, they should be pruned: a cron job to delete all files that were created more than a month ago in this ``logs/`` directory should be sufficient. ``my_nodeid`` this is written by all nodes after startup, and contains a base32-encoded (i.e. human-readable) NodeID that identifies this specific node. This NodeID is the same string that gets displayed on the web page (in the "which peers am I connected to" list), and the shortened form (the first few characters) is recorded in various log messages. ``access.blacklist`` Gateway nodes may find it necessary to prohibit access to certain files. The web-API has a facility to block access to filecaps by their storage index, returning a 403 "Forbidden" error instead of the original file. For more details, see the "Access Blacklist" section of webapi.rst_. Example ======= The following is a sample ``tahoe.cfg`` file, containing values for some of the keys described in the previous section. Note that this is not a recommended configuration (most of these are not the default values), merely a legal one. :: [node] nickname = Bob's Tahoe-LAFS Node tub.port = 34912 tub.location = 123.45.67.89:8098,44.55.66.77:8098 web.port = 3456 log_gatherer.furl = pb://soklj4y7eok5c3xkmjeqpw@192.168.69.247:44801/eqpwqtzm timeout.keepalive = 240 timeout.disconnect = 1800 ssh.port = 8022 ssh.authorized_keys_file = ~/.ssh/authorized_keys [client] introducer.furl = pb://ok45ssoklj4y7eok5c3xkmj@tahoe.example:44801/ii3uumo helper.furl = pb://ggti5ssoklj4y7eok5c3xkmj@helper.tahoe.example:7054/kk8lhr [storage] enabled = True readonly = True reserved_space = 10000000000 [helper] enabled = True Old Configuration Files ======================= Tahoe-LAFS releases before v1.3.0 had no ``tahoe.cfg`` file, and used distinct files for each item. This is no longer supported and if you have configuration in the old format you must manually convert it to the new format for Tahoe-LAFS to detect it. See `historical/configuration.rst`_. .. _historical/configuration.rst: historical/configuration.rst