1 ========================
2 Configuring a Tahoe node
3 ========================
5 1. `Overall Node Configuration`_
6 2. `Client Configuration`_
7 3. `Storage Server Configuration`_
9 5. `Running An Introducer`_
10 6. `Other Files in BASEDIR`_
12 8. `Backwards Compatibility Files`_
15 A Tahoe node is configured by writing to files in its base directory. These
16 files are read by the node when it starts, so each time you change them, you
17 need to restart the node.
19 The node also writes state to its base directory, so it will create files on
22 This document contains a complete list of the config files that are examined
23 by the client node, as well as the state files that you'll observe in its
26 The main file is named 'tahoe.cfg', which is an ".INI"-style configuration
27 file (parsed by the Python stdlib 'ConfigParser' module: "[name]" section
28 markers, lines with "key.subkey: value", rfc822-style continuations). There
29 are other files that contain information which does not easily fit into this
30 format. The 'tahoe create-node' or 'tahoe create-client' command will create
31 an initial tahoe.cfg file for you. After creation, the node will never modify
32 the 'tahoe.cfg' file: all persistent state is put in other files.
34 The item descriptions below use the following types:
37 one of (True, yes, on, 1, False, off, no, 0), case-insensitive
40 a Twisted listening-port specification string, like "tcp:80"
41 or "tcp:3456:interface=127.0.0.1". For a full description of
43 http://twistedmatrix.com/documents/current/api/twisted.application.strports.html
46 a Foolscap endpoint identifier, like
47 pb://soklj4y7eok5c3xkmjeqpw@192.168.69.247:44801/eqpwqtzm
50 Overall Node Configuration
51 ==========================
53 This section controls the network behavior of the node overall: which ports
54 and IP addresses are used, when connections are timed out, etc. This
55 configuration is independent of the services that the node is offering: the
56 same controls are used for client and introducer nodes.
58 If your node is behind a firewall or NAT device and you want other clients to
59 connect to it, you'll need to open a port in the firewall or NAT, and specify
60 that port number in the tub.port option. If behind a NAT, you *may* need to
61 set the tub.location option described below.
67 nickname = (UTF-8 string, optional)
69 This value will be displayed in management tools as this node's "nickname".
70 If not provided, the nickname will be set to "<unspecified>". This string
71 shall be a UTF-8 encoded unicode string.
73 web.port = (strports string, optional)
75 This controls where the node's webserver should listen, providing filesystem
76 access and node status as defined in webapi.txt . This file contains a
77 Twisted "strports" specification such as "3456" or
78 "tcp:3456:interface=127.0.0.1". The 'tahoe create-node' or 'tahoe create-client'
79 commands set the web.port to "tcp:3456:interface=127.0.0.1" by default; this
80 is overridable by the "--webport" option. You can make it use SSL by writing
81 "ssl:3456:privateKey=mykey.pem:certKey=cert.pem" instead.
83 If this is not provided, the node will not run a web server.
85 web.static = (string, optional)
87 This controls where the /static portion of the URL space is served. The
88 value is a directory name (~username is allowed, and non-absolute names are
89 interpreted relative to the node's basedir) which can contain HTML and other
90 files. This can be used to serve a javascript-based frontend to the Tahoe
91 node, or other services.
93 The default value is "public_html", which will serve $BASEDIR/public_html .
94 With the default settings, http://127.0.0.1:3456/static/foo.html will serve
95 the contents of $BASEDIR/public_html/foo.html .
97 tub.port = (integer, optional)
99 This controls which port the node uses to accept Foolscap connections from
100 other nodes. If not provided, the node will ask the kernel for any available
101 port. The port will be written to a separate file (named client.port or
102 introducer.port), so that subsequent runs will re-use the same port.
104 tub.location = (string, optional)
106 In addition to running as a client, each Tahoe node also runs as a server,
107 listening for connections from other Tahoe clients. The node announces its
108 location by publishing a "FURL" (a string with some connection hints) to the
109 Introducer. The string it publishes can be found in
110 $BASEDIR/private/storage.furl . The "tub.location" configuration controls
111 what location is published in this announcement.
113 If you don't provide tub.location, the node will try to figure out a useful
114 one by itself, by using tools like 'ifconfig' to determine the set of IP
115 addresses on which it can be reached from nodes both near and far. It will
116 also include the TCP port number on which it is listening (either the one
117 specified by tub.port, or whichever port was assigned by the kernel when
118 tub.port is left unspecified).
120 You might want to override this value if your node lives behind a firewall
121 that is doing inbound port forwarding, or if you are using other proxies
122 such that the local IP address or port number is not the same one that
123 remote clients should use to connect. You might also want to control this
124 when using a Tor proxy to avoid revealing your actual IP address through the
125 Introducer announcement.
127 The value is a comma-separated string of host:port location hints, like
130 123.45.67.89:8098,tahoe.example.com:8098,127.0.0.1:8098
134 Emulate default behavior, assuming your host has IP address 123.45.67.89
135 and the kernel-allocated port number was 8098:
138 tub.location = 123.45.67.89:8098,127.0.0.1:8098
140 Use a DNS name so you can change the IP address more easily:
143 tub.location = tahoe.example.com:8098
145 Run a node behind a firewall (which has an external IP address) that has
146 been configured to forward port 7912 to our internal node's port 8098:
149 tub.location = external-firewall.example.com:7912
151 Run a node behind a Tor proxy (perhaps via torsocks), in client-only mode
152 (i.e. we can make outbound connections, but other nodes will not be able to
153 connect to us). The literal 'unreachable.example.org' will not resolve, but
154 will serve as a reminder to human observers that this node cannot be
155 reached. "Don't call us.. we'll call you":
158 tub.location = unreachable.example.org:0
160 Run a node behind a Tor proxy, and make the server available as a Tor
161 "hidden service". (this assumes that other clients are running their node
162 with torsocks, such that they are prepared to connect to a .onion address).
163 The hidden service must first be configured in Tor, by giving it a local
164 port number and then obtaining a .onion name, using something in the torrc
167 HiddenServiceDir /var/lib/tor/hidden_services/tahoe
168 HiddenServicePort 29212 127.0.0.1:8098
170 once Tor is restarted, the .onion hostname will be in
171 /var/lib/tor/hidden_services/tahoe/hostname . Then set up your tahoe.cfg
175 tub.location = ualhejtq2p7ohfbb.onion:29212
177 Most users will not need to set tub.location .
179 Note that the old 'advertised_ip_addresses' file from earlier releases is no
180 longer supported. Tahoe 1.3.0 and later will ignore this file.
182 log_gatherer.furl = (FURL, optional)
184 If provided, this contains a single FURL string which is used to contact a
185 'log gatherer', which will be granted access to the logport. This can be
186 used by centralized storage meshes to gather operational logs in a single
187 place. Note that when an old-style BASEDIR/log_gatherer.furl file exists
188 (see 'Backwards Compatibility Files', below), both are used. (for most other
189 items, the separate config file overrides the entry in tahoe.cfg)
191 timeout.keepalive = (integer in seconds, optional)
192 timeout.disconnect = (integer in seconds, optional)
194 If timeout.keepalive is provided, it is treated as an integral number of
195 seconds, and sets the Foolscap "keepalive timer" to that value. For each
196 connection to another node, if nothing has been heard for a while, we will
197 attempt to provoke the other end into saying something. The duration of
198 silence that passes before sending the PING will be between KT and 2*KT.
199 This is mainly intended to keep NAT boxes from expiring idle TCP sessions,
200 but also gives TCP's long-duration keepalive/disconnect timers some traffic
201 to work with. The default value is 240 (i.e. 4 minutes).
203 If timeout.disconnect is provided, this is treated as an integral number of
204 seconds, and sets the Foolscap "disconnect timer" to that value. For each
205 connection to another node, if nothing has been heard for a while, we will
206 drop the connection. The duration of silence that passes before dropping the
207 connection will be between DT-2*KT and 2*DT+2*KT (please see ticket #521 for
208 more details). If we are sending a large amount of data to the other end
209 (which takes more than DT-2*KT to deliver), we might incorrectly drop the
210 connection. The default behavior (when this value is not provided) is to
211 disable the disconnect timer.
213 See ticket #521 for a discussion of how to pick these timeout values. Using
214 30 minutes means we'll disconnect after 22 to 68 minutes of inactivity.
215 Receiving data will reset this timeout, however if we have more than 22min
216 of data in the outbound queue (such as 800kB in two pipelined segments of 10
217 shares each) and the far end has no need to contact us, our ping might be
218 delayed, so we may disconnect them by accident.
220 ssh.port = (strports string, optional)
221 ssh.authorized_keys_file = (filename, optional)
223 This enables an SSH-based interactive Python shell, which can be used to
224 inspect the internal state of the node, for debugging. To cause the node to
225 accept SSH connections on port 8022 from the same keys as the rest of your
230 ssh.authorized_keys_file = ~/.ssh/authorized_keys
232 tempdir = (string, optional)
234 This specifies a temporary directory for the webapi server to use, for
235 holding large files while they are being uploaded. If a webapi client
236 attempts to upload a 10GB file, this tempdir will need to have at least 10GB
237 available for the upload to complete.
239 The default value is the "tmp" directory in the node's base directory (i.e.
240 $NODEDIR/tmp), but it can be placed elsewhere. This directory is used for
241 files that usually (on a unix system) go into /tmp . The string will be
242 interpreted relative to the node's base directory.
250 introducer.furl = (FURL string, mandatory)
252 This FURL tells the client how to connect to the introducer. Each Tahoe grid
253 is defined by an introducer. The introducer's furl is created by the
254 introducer node and written into its base directory when it starts,
255 whereupon it should be published to everyone who wishes to attach a client
258 helper.furl = (FURL string, optional)
260 If provided, the node will attempt to connect to and use the given helper
261 for uploads. See docs/helper.txt for details.
263 key_generator.furl = (FURL string, optional)
265 If provided, the node will attempt to connect to and use the given
266 key-generator service, using RSA keys from the external process rather than
269 stats_gatherer.furl = (FURL string, optional)
271 If provided, the node will connect to the given stats gatherer and provide
272 it with operational statistics.
274 shares.needed = (int, optional) aka "k", default 3
275 shares.total = (int, optional) aka "N", N >= k, default 10
276 shares.happy = (int, optional) 1 <= happy <= N, default 7
278 These three values set the default encoding parameters. Each time a new file
279 is uploaded, erasure-coding is used to break the ciphertext into separate
280 pieces. There will be "N" (i.e. shares.total) pieces created, and the file
281 will be recoverable if any "k" (i.e. shares.needed) pieces are retrieved.
282 The default values are 3-of-10 (i.e. shares.needed = 3, shares.total = 10).
283 Setting k to 1 is equivalent to simple replication (uploading N copies of
286 These values control the tradeoff between storage overhead, performance, and
287 reliability. To a first approximation, a 1MB file will use (1MB*N/k) of
288 backend storage space (the actual value will be a bit more, because of other
289 forms of overhead). Up to N-k shares can be lost before the file becomes
290 unrecoverable, so assuming there are at least N servers, up to N-k servers
291 can be offline without losing the file. So large N/k ratios are more
292 reliable, and small N/k ratios use less disk space. Clearly, k must never be
295 Large values of N will slow down upload operations slightly, since more
296 servers must be involved, and will slightly increase storage overhead due to
297 the hash trees that are created. Large values of k will cause downloads to
298 be marginally slower, because more servers must be involved. N cannot be
299 larger than 256, because of the 8-bit erasure-coding algorithm that Tahoe
302 shares.happy allows you control over the distribution of your immutable file.
303 For a successful upload, shares are guaranteed to be initially placed on
304 at least 'shares.happy' distinct servers, the correct functioning of any
305 k of which is sufficient to guarantee the availability of the uploaded file.
306 This value should not be larger than the number of servers on your grid.
308 A value of shares.happy <= k is allowed, but does not provide any redundancy
309 if some servers fail or lose shares.
311 (Mutable files use a different share placement algorithm that does not
312 consider this parameter.)
315 Storage Server Configuration
316 ============================
321 enabled = (boolean, optional)
323 If this is True, the node will run a storage server, offering space to other
324 clients. If it is False, the node will not run a storage server, meaning
325 that no shares will be stored on this node. Use False this for clients who
326 do not wish to provide storage service. The default value is True.
328 readonly = (boolean, optional)
330 If True, the node will run a storage server but will not accept any shares,
331 making it effectively read-only. Use this for storage servers which are
332 being decommissioned: the storage/ directory could be mounted read-only,
333 while shares are moved to other servers. Note that this currently only
334 affects immutable shares. Mutable shares (used for directories) will be
335 written and modified anyway. See ticket #390 for the current status of this
336 bug. The default value is False.
338 reserved_space = (str, optional)
340 If provided, this value defines how much disk space is reserved: the storage
341 server will not accept any share which causes the amount of free disk space
342 to drop below this value. (The free space is measured by a call to statvfs(2)
343 on Unix, or GetDiskFreeSpaceEx on Windows, and is the space available to the
344 user account under which the storage server runs.)
346 This string contains a number, with an optional case-insensitive scale
347 suffix like "K" or "M" or "G", and an optional "B" or "iB" suffix. So
348 "100MB", "100M", "100000000B", "100000000", and "100000kb" all mean the same
349 thing. Likewise, "1MiB", "1024KiB", and "1048576B" all mean the same thing.
353 expire.override_lease_duration =
358 These settings control garbage-collection, in which the server will delete
359 shares that no longer have an up-to-date lease on them. Please see the
360 neighboring "garbage-collection.txt" document for full details.
366 A "helper" is a regular client node that also offers the "upload helper"
372 enabled = (boolean, optional)
374 If True, the node will run a helper (see docs/helper.txt for details). The
375 helper's contact FURL will be placed in private/helper.furl, from which it
376 can be copied to any clients which wish to use it. Clearly nodes should not
377 both run a helper and attempt to use one: do not create both helper.furl and
378 run_helper in the same node. The default is False.
381 Running An Introducer
382 =====================
384 The introducer node uses a different '.tac' file (named introducer.tac), and
385 pays attention to the "[node]" section, but not the others.
387 The Introducer node maintains some different state than regular client
390 BASEDIR/introducer.furl : This is generated the first time the introducer
391 node is started, and used again on subsequent runs, to give the introduction
392 service a persistent long-term identity. This file should be published and
393 copied into new client nodes before they are started for the first time.
396 Other Files in BASEDIR
397 ======================
399 Some configuration is not kept in tahoe.cfg, for the following reasons:
401 * it is generated by the node at startup, e.g. encryption keys. The node
402 never writes to tahoe.cfg
403 * it is generated by user action, e.g. the 'tahoe create-alias' command
405 In addition, non-configuration persistent state is kept in the node's base
406 directory, next to the configuration knobs.
408 This section describes these other files.
411 This contains an SSL private-key certificate. The node
412 generates this the first time it is started, and re-uses it on subsequent
413 runs. This certificate allows the node to have a cryptographically-strong
414 identifier (the Foolscap "TubID"), and to establish secure connections to
418 Nodes which host StorageServers will create this directory to hold
419 shares of files on behalf of other clients. There will be a directory
420 underneath it for each StorageIndex for which this node is holding shares.
421 There is also an "incoming" directory where partially-completed shares are
422 held while they are being received.
425 this file defines the client, by constructing the actual Client
426 instance each time the node is started. It is used by the 'twistd'
427 daemonization program (in the "-y" mode), which is run internally by the
428 "tahoe start" command. This file is created by the "tahoe create-node" or
429 "tahoe create-client" commands.
432 this file contains a FURL that provides access to a
433 control port on the client node, from which files can be uploaded and
434 downloaded. This file is created with permissions that prevent anyone else
435 from reading it (on operating systems that support such a concept), to insure
436 that only the owner of the client node can use this feature. This port is
437 intended for debugging and testing use.
440 this file contains a FURL that provides access to a
441 'log port' on the client node, from which operational logs can be retrieved.
442 Do not grant logport access to strangers, because occasionally secret
443 information may be placed in the logs.
446 if the node is running a helper (for use by other
447 clients), its contact FURL will be placed here. See docs/helper.txt for more
450 private/root_dir.cap (optional)
451 The command-line tools will read a directory
452 cap out of this file and use it, if you don't specify a '--dir-cap' option or
453 if you specify '--dir-cap=root'.
455 private/convergence (automatically generated)
456 An added secret for encrypting
457 immutable files. Everyone who has this same string in their
458 private/convergence file encrypts their immutable files in the same way when
459 uploading them. This causes identical files to "converge" -- to share the
460 same storage space since they have identical ciphertext -- which conserves
461 space and optimizes upload time, but it also exposes files to the possibility
462 of a brute-force attack by people who know that string. In this attack, if
463 the attacker can guess most of the contents of a file, then they can use
464 brute-force to learn the remaining contents.
466 So the set of people who know your private/convergence string is the set of
467 people who converge their storage space with you when you and they upload
468 identical immutable files, and it is also the set of people who could mount
471 The content of the private/convergence file is a base-32 encoded string. If
472 the file doesn't exist, then when the Tahoe client starts up it will generate
473 a random 256-bit string and write the base-32 encoding of this string into
474 the file. If you want to converge your immutable files with as many people as
475 possible, put the empty string (so that private/convergence is a zero-length
482 Each Tahoe node creates a directory to hold the log messages produced
483 as the node runs. These logfiles are created and rotated by the "twistd"
484 daemonization program, so logs/twistd.log will contain the most recent
485 messages, logs/twistd.log.1 will contain the previous ones, logs/twistd.log.2
486 will be older still, and so on. twistd rotates logfiles after they grow
487 beyond 1MB in size. If the space consumed by logfiles becomes troublesome,
488 they should be pruned: a cron job to delete all files that were created more
489 than a month ago in this logs/ directory should be sufficient.
492 this is written by all nodes after startup, and contains a
493 base32-encoded (i.e. human-readable) NodeID that identifies this specific
494 node. This NodeID is the same string that gets displayed on the web page (in
495 the "which peers am I connected to" list), and the shortened form (the first
496 characters) is recorded in various log messages.
498 Backwards Compatibility Files
499 =============================
501 Tahoe releases before 1.3.0 had no 'tahoe.cfg' file, and used distinct files
502 for each item listed below. For each configuration knob, if the distinct file
503 exists, it will take precedence over the corresponding item in tahoe.cfg.
505 =========================== =============================== =================
506 Config setting File Comment
507 =========================== =============================== =================
508 [node]nickname BASEDIR/nickname
509 [node]web.port BASEDIR/webport
510 [node]tub.port BASEDIR/client.port (for Clients, not Introducers)
511 [node]tub.port BASEDIR/introducer.port (for Introducers, not Clients) (note that, unlike other keys, tahoe.cfg overrides this file)
512 [node]tub.location BASEDIR/advertised_ip_addresses
513 [node]log_gatherer.furl BASEDIR/log_gatherer.furl (one per line)
514 [node]timeout.keepalive BASEDIR/keepalive_timeout
515 [node]timeout.disconnect BASEDIR/disconnect_timeout
516 [client]introducer.furl BASEDIR/introducer.furl
517 [client]helper.furl BASEDIR/helper.furl
518 [client]key_generator.furl BASEDIR/key_generator.furl
519 [client]stats_gatherer.furl BASEDIR/stats_gatherer.furl
520 [storage]enabled BASEDIR/no_storage (False if no_storage exists)
521 [storage]readonly BASEDIR/readonly_storage (True if readonly_storage exists)
522 [storage]sizelimit BASEDIR/sizelimit
523 [storage]debug_discard BASEDIR/debug_discard_storage
524 [helper]enabled BASEDIR/run_helper (True if run_helper exists)
525 =========================== =============================== =================
527 Note: the functionality of [node]ssh.port and [node]ssh.authorized_keys_file
528 were previously combined, controlled by the presence of a
529 BASEDIR/authorized_keys.SSHPORT file, in which the suffix of the filename
530 indicated which port the ssh server should listen on, and the contents of the
531 file provided the ssh public keys to accept. Support for these files has been
532 removed completely. To ssh into your Tahoe node, add [node]ssh.port and
533 [node].ssh_authorized_keys_file statements to your tahoe.cfg.
535 Likewise, the functionality of [node]tub.location is a variant of the
536 now-unsupported BASEDIR/advertised_ip_addresses . The old file was additive
537 (the addresses specified in advertised_ip_addresses were used in addition to
538 any that were automatically discovered), whereas the new tahoe.cfg directive
539 is not (tub.location is used verbatim).
545 The following is a sample tahoe.cfg file, containing values for all keys
546 described above. Note that this is not a recommended configuration (most of
547 these are not the default values), merely a legal one.
552 nickname = Bob's Tahoe Node
554 tub.location = 123.45.67.89:8098,44.55.66.77:8098
556 log_gatherer.furl = pb://soklj4y7eok5c3xkmjeqpw@192.168.69.247:44801/eqpwqtzm
557 timeout.keepalive = 240
558 timeout.disconnect = 1800
560 ssh.authorized_keys_file = ~/.ssh/authorized_keys
563 introducer.furl = pb://ok45ssoklj4y7eok5c3xkmj@tahoe.example:44801/ii3uumo
564 helper.furl = pb://ggti5ssoklj4y7eok5c3xkmj@helper.tahoe.example:7054/kk8lhr
568 readonly_storage = True
569 sizelimit = 10000000000