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Using Tahoe-LAFS with an anonymizing network: Tor, I2P
- Use cases
- Native Tor integration for Tahoe-LAFS
- Software Dependencies
- Configuration
- Performance and security issues of Tor Hidden Services
- Torsocks: the old way of configuring Tahoe-LAFS to use Tor
Use cases
Tor is an anonymizing network used to help hide the identity of internet clients and servers. Please see the Tor Project's website for more information: https://www.torproject.org/
Informative description about what i2p is... here.
There are three potential use-cases for Tahoe-LAFS on the client side:
- User does not care to protect their anonymity or to connect to anonymous storage servers. This document is not useful to you... so stop reading.
- User does not care to protect their anonymity but they wish to connect to Tahoe-LAFS storage servers which are accessbile only via Tor Hidden Services or I2P. (For Tor users this means only use Tor if the endpoint string has a .onion address.)
- User wishes to always use an anonymizing network (Tor, I2P) to protect their anonymity when connecting to Tahoe-LAFS storage grids (whether or not the storage servers are anonymous).
For Tahoe-LAFS storage servers there are three use-cases:
Storage server operator does not care to protect their own anonymity nor to help the clients protect theirs. Stop reading this document and run your Tahoe-LAFS storage server using publicly routed TCP/IP.
The operator does not require anonymity for the storage server, but they want it to be available over both publicly routed TCP/IP and through an anonymizing network (I2P, Tor Hidden Services). One possible reason to do this is because being reachable through an anonymizing network is a convenient way to bypass NAT or firewall that prevents publicly routed TCP/IP connections to your server. Another is that making your storage server reachable through an anonymizing network can provide better protection for your clients who themselves use that anonymizing network to protect their anonymity.
See this Tor Project page for more information about Tor Hidden Services: https://www.torproject.org/docs/hidden-services.html.en
See this I2P Project page for more information about I2P: https://...
The operator wishes to protect their anonymity by making their Tahoe server accessible only via Tor Hidden Services.
Native Tor integration for Tahoe-LAFS
Native Tor integration for Tahoe-LAFS utilizes the Twisted endpoints API:: * https://twistedmatrix.com/documents/current/core/howto/endpoints.html
Twisted's endpoint parser plugin system is extensible via installing additional Twisted packages. The native Tor integration for Tahoe-LAFS uses endpoint and parser plugins from the txsocksx and txtorcon modules. Although the Twisted endpoint API is very flexible it is missing a feature so that servers can be written in an endpoint agnostic style. We've opened a Twisted trac ticket for this feature here:: * https://twistedmatrix.com/trac/ticket/7603
Once this ticket is resolved then an additional changes can be made to Foolscap so that it's server side API is completely endpoint agnostic which will allow users to easily to use Tahoe-LAFS with many protocols on the server side.
txsocksx will try to use the system tor's SOCKS port if available; attempts are made on ports 9050 and 9151. Currently the maintainer of txsocksx has not merged in our code for the Tor client endpoint. We'll use this branch until the Tor endpoint code is merged upstream:: * https://github.com/david415/txsocksx/tree/endpoint_parsers_retry_socks
txtorcon will use the system tor control port to configure Tor Hidden Services pending resolution of tor trac ticket 11291:: * https://trac.torproject.org/projects/tor/ticket/11291
See also Tahoe-LAFS Tor related tickets #1010 and #517.
Software Dependencies
Tor (tor) must be installed. See here: https://www.torproject.org/docs/installguide.html.en
The "Tor-friendly" branch of txsocksx must be installed ( Once this is merged then you can use upstream txsocksx; https://github.com/habnabit/txsocksx/pull/8 ) :
pip install git+https://github.com/david415/txsocksx.gittxtorcon must be installed :
pip install txtorcon
Once these software dependencies are installed and the Tahoe-LAFS node is restarted, then no further configuration is necessary for "unsafe" Tor connectivity to other Tahoe-LAFS nodes (client use-case 2 from Use cases, above).
In order to implement client use-case 3 or server use-cases 2 or 3, further configuration is necessary.
Configuration
[node] anonymize = (boolean, optional)
- This specifies two changes in behavior:
- Transform all non-Tor client endpoints into Tor client endpoints.
- Force
tub.locationto be set to "safe" values.
This option is critical to preserving the client's anonymity (client use-case 3 from Use cases, above). It is also necessary to preserve a server's anonymity (server use-case 3).
When anonymize is set to true then tub.location does not need to be specified... and it is an error to specify a tub.location value that contains anything other than "UNREACHABLE" or a Tor Hidden Service Twisted endpoint descriptor string.
If server use-case 2 from Use cases above is desired then you can set tub.location to a Tor Hidden Service endpoint string AND "AUTODETECT" like this:: tub.location = "AUTODETECT,onion:80:hiddenServiceDir=/var/lib/tor/my_service"
It is an error to specify a tub.location value that contains "AUTODETECT" when anonymize is also set to true.
Operators of Tahoe-LAFS storage servers wishing to protect the identity of their storage server should set anonymize to true and specify a Tor Hidden Service endpoint descriptor string for the tub.location value in the tahoe.cfg like this:: tub.location = "onion:80:hiddenServiceDir=/var/lib/tor/my_service"
Setting this configuration option is necessary for Server use-cases 2 and 3 (from Use cases, above).
Performance and security issues of Tor Hidden Services
If you are running a server which does not itself need to be anonymous, should you make it reachable as a Tor Hidden Service or not? Or should you make it reachable both as a Tor Hidden Service and as a publicly traceable TCP/IP server?
There are several trade-offs effected by this decision.
NAT/Firewall penetration
Making a server be reachable as a Tor Hidden Service makes it reachable even if there are NATs or firewalls preventing direct TCP/IP connections to the server.
Anonymity
Making a Tahoe-LAFS server accessible only via Tor Hidden Services can be used to guarantee that the Tahoe-LAFS clients use Tor to connect. This prevents misconfigured clients from accidentally de-anonymizing themselves by connecting to your server through the traceable Internet.
Also, interaction, through Tor, with a Tor Hidden Service may be more protected from network traffic analysis than interaction, through Tor, with a publicly traceable TCP/IP server.
XXX is there a document maintained by Tor developers which substantiates or refutes this belief? If so we need to link to it. If not, then maybe we should explain more here why we think this?
Performance
A client connecting to a Tahoe-LAFS server through Tor incurs substantially higher latency and sometimes worse throughput than the same client connecting to the same server over a normal traceable TCP/IP connection.
A client connecting to a Tahoe-LAFS server which is a Tor Hidden Service incurs much more latency and probably worse throughput.
Positive and negative effects on other Tor users
Sending your Tahoe-LAFS traffic over Tor adds cover traffic for other Tor users who are also transmitting bulk data. So that is good for them -- increasing their anonymity.
However, it makes the performance of other Tor users' interactive sessions -- e.g. ssh sessions -- much worse. This is because Tor doesn't currently have any prioritization or quality-of-service features, so someone else's ssh keystrokes may have to wait in line while your bulk file contents get transmitted. The added delay might make other people's interactive sessions unusable.
Both of these effects are doubled if you upload or download files to a Tor Hidden Service, as compared to if you upload or download files over Tor to a publicly traceable TCP/IP server.
Native I2P Integration for Tahoe-LAFS
Really cool and interesting description of how the I2p integration works...
Software Dependencies
I2p software deps here
Configuration
informative configuration info for i2p users goes here
link to tahoe trac ticket regarding client endpoint string parameter concatenation
Performance and security issues of I2p (if applicable)
i2p info here
Torsocks: the old way of configuring Tahoe-LAFS to use Tor
Before the native Tor integration for Tahoe-LAFS, users would use Torsocks. Please see these pages for more information about Torsocks: https://code.google.com/p/torsocks/
https://trac.torproject.org/projects/tor/wiki/doc/torsocks
https://github.com/dgoulet/torsocks/
Starting And Stopping
Assuming you have your Tahoe-LAFS node directory placed in ~/.tahoe, use Torsocks to start Tahoe like this :
usewithtor tahoe startLikewise if restarting, then with Torsocks like this :
usewithtor tahoe restartAfter Tahoe is started, additional Tahoe commandline commands will not need to be executed with Torsocks because the Tahoe gateway long running process handles all the network connectivity.
Configuration
Before Tahoe-LAFS had native Tor integration it would deanonymize the user if a tub.location value is not set. This is because Tahoe-LAFS at that time defaulted to autodetecting the external IP interface and announced that IP address to the server.
Tahoe-LAFS + Torsocks client configuration
NOTE: before diving into Tor + Tahoe-LAFS configurations you should ensure your familiarity with with installing Tor on unix systems. If you intend to operate an anonymous Tahoe-LAFS storage node then you will also want to read about configuring Tor Hidden Services. See here:
https://www.torproject.org/docs/tor-doc-unix.html.en
https://www.torproject.org/docs/tor-hidden-service.html.en
Run a node using 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 'client.fakelocation' 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 = tcp:interface=127.0.0.1:8098
tub.location = client.fakelocation:0Tahoe-LAFS + Torsocks storage server configuration
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.) Your instance of Tor should be configured for Hidden Services... for instance specify the Hidden Service listening on port 29212 should proxy to 127.0.0.1 port 8098 by adding this to your torrc :
HiddenServiceDir /var/lib/tor/services/tahoe-storage
HiddenServicePort 29212 127.0.0.1:8098once Tor is restarted, the .onion hostname will be in /var/lib/tor/services/tahoe-storage/hostname. Then set up your tahoe.cfg like:
tub.port = tcp:interface=127.0.0.1:8098
tub.location = ualhejtq2p7ohfbb.onion:29212Troubleshooting
On some NetBSD systems, torsocks may segfault:
$ torsocks telnet www.google.com 80
Segmentation fault (core dumped)and backtraces show looping libc and syscalls:
#7198 0xbbbda26e in *__socket30 (domain=2, type=1, protocol=6) at socket.c:64
#7199 0xbb84baf9 in socket () from /usr/lib/libc.so.12
#7200 0xbbbda19b in tsocks_socket (domain=2, type=1, protocol=6) at socket.c:56
#7201 0xbbbda26e in *__socket30 (domain=2, type=1, protocol=6) at socket.c:64
#7202 0xbb84baf9 in socket () from /usr/lib/libc.so.12
[...etc...]This has to do with the nature of the torsocks socket() call wrapper being unaware of NetBSD's internal binary backwards compatibility.
Information on a the first parts of a solution patch can be found in a tor-dev thread here from Thomas Klausner:
As of this writing, torsocks still exists in the pkgsrc wip tree here:
but the NetBSD-specific patches have been merged upstream into torsocks as of commitid 6adfba809267d9c217906d6974468db22293ab9b:
Legacy I2P Tahoe-LAFS Configuration
legacy i2p info here