This note documents how to deploy a secure, hidden tahoe-lafs grid over the tor network. The storage servers are hard-coded so no introducer is required. All storage servers are accessed only through their onion address, and the onion addresses are protected using stealth access mode. Thus, a cookie for each storage server in the grid is included in the client's torrc file.

The possibility of doing this was first discussed in the comments following a posting on the tor blog. Below I summarize the steps required to actually implement the secure, hidden tahoe-lafs grid.

In what follows, we will assume that the storage server configuration directory is located at ~/.tahoe-server and the client configuration directory is located at ~/.tahoe. Modify the instructions below according to your installation. The easiest way to create these configuration directories is to use the create-node (for the servers) and create-client commands. On each server node, run tahoe create-node --hostname=fixme .tahoe-server. This will generate a skeleton configuration for the server. Similarly, the command tahoe create-client .tahoe wil create a skeleton client configuration. You will modify these configurations as described below.

Storage server configuration

For each storage server, the first step is to create a tor hidden service that points to the local tub.port. Include the following lines in the storage server's /etc/tor/torrc file (modify the HiddenServiceDir and HiddenServicePort parameters as appropriate for your installation):

HiddenServiceDir /var/lib/tor/tahoe-server/
HiddenServiceAuthorizeClient stealth server_1
HiddenServicePort 3457 127.0.0.1:3457

and restart the storage server's tor daemon.

To determine the onion address for the storage server, cat /var/lib/tor/tahoe-server/hostname. The output of this command will look something like:

adfmcm3mkfkx8fds.onion fdjkhasz734mxhuaiTUjfs # client: server_1

The first string in this line is the hidden service onion address, and the second string is the stealth cookie. The comment following the # symbol is just to remind you which storage server these credentials correspond to.

Repeat this process on each storage server node. You will get a unique onion address and stealth cookie for each storage server. Save these for later

The ~/.tahoe-server/tahoe.cfg file for each server node looks like this:

# -*- mode: conf; coding: utf-8 -*-

# This file controls the configuration of the Tahoe node that
# lives in this directory. It is only read at node startup.
# For details about the keys that can be set here, please
# read the 'docs/configuration.rst' file that came with your
# Tahoe installation.


[node]
nickname = node_l
reveal-IP-address = false
web.port =
web.static = public_html
tub.port = tcp:3457:interface=127.0.0.1
tub.location = tor:adfmcm3mkfkx8fds.onion:3457

[client]
# Which services should this client connect to?
introducer.furl =
helper.furl =
#stats_gatherer.furl =

# Encoding parameters this client will use for newly-uploaded files
# This can be changed at any time: the encoding is saved in
# each filecap, and we can download old files with any encoding
# settings
shares.needed = 3
shares.happy = 7
shares.total = 10

[storage]
# Shall this node provide storage service?
enabled = true
#readonly =
reserved_space = 1G
expire.enabled = true
expire.mode = age
expire.override_lease_duration = 3 months

[helper]
# Shall this node run a helper service that clients can use?
enabled = false

[connections]
tcp = tor

The onion address set in tub.location must match the onion address you obtained for that storage server node. The port must also match that set in the HiddenServicePort parameter. Adjust parameters such as nickname, lease expiration, and reserved_space as appropriate for your installation.

Start each storage server with tahoe start ~/.tahoe-server, modifying the server directory as appropriate. The storage grid setup is now complete and all of your storage servers should be running.

Client configuration

The first step is to configure the client's tor daemon so that it can find and access the storage server onions. Add the following lines to the bottom of /etc/tor/torrc on the client node (one line for each storage server):

HidServAuth adfmcm3mkfkx8fds.onion fdjkhasz734mxhuaiTUjfs # client: server_1
HidServAuth zxlkj33klsjfu3nf.onion lajdf8z33nmnnxuiufjlds # client: server_2
...

The strings following the HidServAuth parameter should match those you saved for later in the server configuration instructions above. Restart the tor daemon.

The next step is to create the ~/.tahoe/private/servers.yaml file. This file contains hardcoded information on how the client will connect to the storage servers. In order to enhance the privacy and anonymity of the grid, no introducer or helper nodes are used. The formatting of the servers.yaml file is critical. Be sure to follow the formatting exactly as shown here (two spaces per indentation).

storage:
  v0-lkzjkleloafjko3kfldskojfiiui34ljkkljfadkljfdjkljfakl:
    ann:
      nickname: server_1
      anonymous-storage-FURL: pb://hxmipb3sfebovhev2mwbumtcn276ph6z@tor:adfmcm3mkfkx8fds.onion:3457/7pqmhbq2s2m4ms72zaz23jixd64wt34h
# storage
  v0-lj3lmziojprmklzxpoguik33jkfl889lzjfskljfkslfjkdslffd:
    ann:
      nickname: server_2
      anonymous-storage-FURL: pb://syw73rxtygpomuhtsqzqdhhtoopwo7gp@tor:zxlkj33klsjfu3nf.onion:3457/c4iahx6xbpzrxrn5rjnc4rie23gcglk3
# storage
...

The strings beginning with v0- are the public keys of each of the storage servers. These are in ~/.tahoe-server/node.pubkey. Be sure to just include the part of the key beginning v0- in the servers.yaml file. Replace each storage server public key in servers.yaml with your storage server's public key.

The anonymous-storage-FURL's beginning with pb:// should be replaced with the FURL's from your actual storage servers. The FURL for each storage server can be found at ~/.tahoe-server/private/storage.furl. Apparently, the # storage comment lines between each storage server's information are required, so be sure to include these.

The client's ~/.tahoe/tahoe.cfg file should look like this:

[node]
nickname = client_1
reveal-ip-address = false
web.port = tcp:3456:interface=127.0.0.1
web.static = public_html
tub.port = disabled
tub.location = disabled

[client]
introducer.furl =
#helper.furl =
shares.needed = 3
shares.happy = 7
shares.total = 10

[storage]
enabled = false
reserved_space = 1G

[helper]
enabled = false

[connections]
tcp = tor

Edit the client nickname parameter as appropriate, as well as the web.port and shares.* parameters.

Finally, start the client with tahoe start ~/.tahoe.

Browse to localhost:3456 and you should see your new grid connected!

Note added 1/30/2017

After I posted this note, a reader on the #tahoe-lafs channel on freenode pointed me to a pastebin by him that summarized the format for the servers.yaml file nicely. You can read his discussion here.