[tor-reports] Damian's Status Report - January 2015

[Damian Johnson]

This was a great start to the year! Highlight was lunch with David White,
author of Battle for Wesnoth who also gave me a tour of Valve. But January
had lots of neat Tor stuff too...

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Nyx Connections Despite DisableDebuggerAttachment
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For years Tor's DisableDebuggerAttachment has been the bane of Nyx. The
feature wasn't intended to effect us, but screws with proc permissions
breaking every connection resolver we have.

Resolvers read /proc/<pid>/fd to get connection inodes, then use that
to determine what from /proc/net/tcp belongs to our process. Tor's
DisableDebuggerAttachment breaks that by making /proc/<pid>/fd only
readable by root. However, even without knowing the inodes we can
identify Tor related connections by if they go to a relay or our
Tor ports. This is exactly what Nyx already does to identify a
connection's type.

TL;DR. Connection resolution now works all the time. Only drawbacks are...

* This will blend connections when running multiple Tor processes.

* Connection resolution can't work until we have consensus information. This
  can take a few seconds when starting up.

* We can't show client or exit connections. Nyx already scrubbed these so
  no big loss, but means we now can't even show that they exist.

Small drawbacks to have the connection panel work by default once again.
User can still set 'DisableDebuggerAttachment 0' in their torrc for more
reliable connection resolution.

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IPv6 Connection Resolvers
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Thanks to toralf Stem can now retrieve IPv6 connection information. More
important for users, this means Nyx's connection panel now works for IPv6
relays!

https://trac.torproject.org/projects/tor/ticket/18079

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Few other noteworthy things...

* Working with Karsten and Philipp we now have benchmarks for how our
  descriptor parsing libraries perform...

  https://stem.torproject.org/tutorials/mirror_mirror_on_the_wall.html#are-there-any-other-parsing-libraries
  https://lists.torproject.org/pipermail/tor-dev/2016-January/010230.html

* Nyx is faster! There's still a lot of room to improve but quick pass over
  low hanging fruit reduced its load by an order of magnitude.

Cheers! -Damian