[tor-relays] New obfsproxy transport: scramblesuit [bridge operators: please upgrade!]

[George Kadianakis]

Greetings,

a few days ago we integrated ScrambleSuit to obfsproxy. ScrambleSuit
is a pluggable transport by Philipp Winter; you can find more about it
at: http://www.cs.kau.se/philwint/scramblesuit/

If you are running a bridge, please consider upgrading your obfsproxy
to the latest version (0.2.6) by using pip or fetching the latest git
master.  Unfortunately, we don't have Linux packages yet, but we will
hopefully have some soon. In the meanwhile, we would appreciate some
testing :)

After you upgrade obfsproxy, please change your ServerTransportPlugin
line from:
     ServerTransportPlugin obfs2,obfs3 exec /usr/bin/obfsproxy managed 
to:
     ServerTransportPlugin obfs3,scramblesuit exec /usr/bin/obfsproxy managed 

This will disable obfs2 [0] and enable scramblesuit.

It's also important to know that scramblesuit is a password-based
pluggable transport, which means that each scramblesuit bridge has a
password and if the user doesn't know the password he/she can't
connect to the bridge. If you publishing your bridge to BridgeDB, Tor
will automatically send the ScrambleSuit password to BridgeDB so that
clients can get it. By default ScrambleSuit will generate a random
password; if you want to specify your own password, you can use a
torrc line like this:
      ServerTransportOptions scramblesuit password=LLDNOWV7I4P6RKFJMDEMIY2GNU2IQISA

By the way, expect not to see any scramblesuit users in the
beginning. After a few people have set up scramblesuit bridges, we
will roll out a Tor Browser Bundle with scramblesuit enabled.

Feel free to ask any questions you have!

Thanks!

PS: If you are running a bridge without any pluggable transports,
    please consider installing obfsproxy [1]. Normal bridges are not
    hard to block these days and we are working on increasing the
    number of obfuscated bridges out there.

[0]: https://trac.torproject.org/projects/tor/ticket/10314
[1]: https://www.torproject.org/projects/obfsproxy.html.en