Shirish Agarwal: The road to TOR
Happy Independence Day to all. I had been looking forward to this day so I can use to share with my brothers and sisters what little I know about TOR . Independence means so many things to many people. For me, it means having freedom, valuing it and using it to benefit not just to ourselves but to people at large. And for that to happen, at least on the web, it has to rise above censorship if we are to get there at all. I am 40 years old, and if I can t read whatever I want to read without asking the state-military-Corporate trinity than be damned with that. Debconf was instrumental as I was able to understand and share many of the privacy concerns that we all have. This blog post is partly a tribute to being part of a community and being part of Debconf16.
So, in that search for privacy couple of years ago, I came across TOR . TOR stands for The Onion Router project. Explaining tor is simple. Let us take the standard way in which we approach the website using a browser or any other means.
a. We type out a site name, say debian.org in the URL/URI bar .b. Now the first thing the browser would do is look into its DNS Cache to see if the name/URL has been used before. If it is something like debian.org which has been used before and is *fresh* and there is content already it would serve the content from the cache there itself.
c. In case, if it s not or the content is stale or something, it would generate a DNS lookup through the various routing tables till the DNS IP Address is found and information relayed to the browser.
d. The browser takes the IP Address and opens a TCP connection to the server, you have the handshake happen and after that it s business as usual.
e. In case if it doesn t work, you could get errors like Could not connect to server xyz or some special errors with error codes. This is a much simplified version of what happens or goes through normally with most/all of the browsers. One good way to see how the whole thing happens is to use traceroute and use the whois service. For e.g.
[$] traceroute debian.org
and then
[$] whois 5.153.231.4 grep inetnum
inetnum: 5.153.231.0 - 5.153.231.255
Just using whois IP Address gives much more. I just shared a short version because I find it interesting that Debian has booked all 255 possible IP Addresses but speculating on that would be probably be a job for a different day.
Now the difference when using TOR are two things
a. The conversation is encrypted (somewhat like using https but encrypted through the relays)b. The conversation is relayed over 2-3 relays and it will give a somewhat different identification to the DNS server at the other end.
c. It is only at the end-points that the conversation will be in plain text. For e.g. the TOR connection I m using atm is from me France (relay) Switzerland (relay) Germany (relay) WordPress.com . So wordpress thinks that all the connection is happening via Germany while I m here in India. It would also tells that I m running MS-Windows some version and a different browser while I m from somewhere in India, on Debian, using another browser altogether
There are various motivations for doing that. For myself, I m just a private person and do not need or want that any other person/s or even the State should be looking over my shoulder as to what I m doing. And the argument that we need to spy on citizens because Terrorists are there doesn t hold water over me. There are many ways in which they can pass messages even without tor or web. The Government-Corporate-Military just get more powerful if and when they know what common people think, do, eat etc.
So the question is how does you install tor if you a private sort of person . If you are on a Debian machine, you are one step closer to doing that.
So the first thing that you need to do is install the following
$ sudo aptitude install ooniprobe python-certifi tor tor-geoipdb torsocks torbrowser-launcher
Once the above is done, then run torbrowser-launcher. This is how it would work out the first time it is run
[$] torbrowser-launcher
Tor Browser Launcher
By Micah Lee, licensed under MIT
version 0.2.6
https://github.com/micahflee/torbrowser-launcher
Creating GnuPG homedir /home/shirish/.local/share/torbrowser/gnupg_homedir
Downloading and installing Tor Browser for the first time.
Downloading https://dist.torproject.org/torbrowser/update_2/release/Linux_x86_64-gcc3/x/en-US
Latest version: 6.0.3
Downloading https://dist.torproject.org/torbrowser/6.0.3/tor-browser-linux64-6.0.3_en-US.tar.xz.asc
Downloading https://dist.torproject.org/torbrowser/6.0.3/tor-browser-linux64-6.0.3_en-US.tar.xz
Verifying signature
Extracting tor-browser-linux64-6.0.3_en-US.tar.xz
Running /home/shirish/.local/share/torbrowser/tbb/x86_64/tor-browser_en-US/start-tor-browser.desktop
Launching './Browser/start-tor-browser --detach'...
As can be seen above, you basically download the tor browser remotely from the website. Obviously, for this port 80 needs to be opened.
One of the more interesting things is that it tells you where it installs the browser.
/home/shirish/.local/share/torbrowser/tbb/x86_64/tor-browser_en-US/Browser/start-tor-browser and then detaches.
The first time the TOR browser actually runs it looks something similar to this
Torbrowser picture
[$] alias tor
tor=/home/shirish/.local/share/torbrowser/tbb/x86_64/tor-browser_en-US/Browser/start-tor-browser
It is suggested that you do not use the same usernames on the onion network.
Also apart from the regular URL addresses such as flossexperiences.wordpress.com you will also see sites such as https://www.abc12defgh3ijkl.onion.to (fictional address)
Now there would be others who would want to use the same/similar settings say as there are in their Mozilla Firefox installation.
To do that do the following steps
a. First close down both Torbrowser and Mozilla Firefox .b. Open your file browser and go to where your mozilla profile details are. In typical Debian installations it is at
~/.mozilla/firefox/5r7t1r92.default
In the next tab, navigate to
~/.local/share/torbrowser/tbb/x86_64/tor-browser_en-US/Browser/TorBrowser/Data/Browser/profile.default
c. Now copy the following files over from your mozilla profile to your tor browser profile and you can resume where you left off.
- cert8.db
chromeappsstore.sqlite
content-prefs.sqlite
cookies.sqlite
formhistory.sqlite
key3.db
logins.json (Firefox 32 and above)
mimeTypes.rdf
permissions.sqlite
persdict.dat
places.sqlite
signons3.txt (if exists)
webappsstore.sqlite
-
bookmarkbackups
chrome (if it exists)
searchplugins (if it exists)
Filed under: Miscellenous Tagged: #anonymity, #Debconf16, #debian, #tor, #torbrowser, GNU, Linux, Privacy
A while back, I found myself in need of some TLS certificates set up and issued for a testing environment.
I remembered there was some code for issuing TLS certs in Docker, so I yanked some of that code and made a sensable CLI API over it.
Thus was born 
At some point back when the dinosaurs roamed the Earth and I was in
high school, I borrowed my first digital signal processing book from a friend.
I later went on to an engineering education and master's thesis about DSP,
but the very basics of DSP never stop to fascinate me. Today, I wanted to
write something about one of them and how it affects audio processing in
Nageru (and finally, how Debian's policies put me in a bit of a bind on
this issue).
DSP texts tend to obscure profound truths with large amounts of maths,
so I'll try to present a somewhat less general result that doesn't require
going into the mathematical details. That rule is:
Adding a signal to weighted, delayed copies of itself is a filtering operation.
(It's simple, but ignoring it will have sinister effects, as we'll see later.)
Let's see exactly what that means with a motivating example. Let's say that
I have a signal where I want to get rid of (or rather, reduce) high frequencies.
The simplest way I can think of is to add every neighboring sample; that is,
set yn = xn + xn-1. For each sample, we
add the previous sample, ie., the signal as it was one sample ago.
(We ignore what happens at the edges; the common
convention is to assume signals extend out to infinity with zeros.)
What effect will this have? We can figure it out with some trigonometry,
but let's just demonstrate it by plotting instead: We assume 48 kHz sample rate
(which means that our one-sample delay is 20.83 s) and a 22 kHz
note (definitely treble!), and plot the signal with one-sample delay
(the x axis is sample number):
As you can see, the resulting signal is a new signal of the same frequency
(which is always true; linear filtering can never create new frequencies,
just boost or dampen existing ones), but with much lower amplitude.
The signal and the delayed version of it end up cancelling each other mostly
out. Also note that there signal has changed phase; the resulting signal
has been a bit delayed compared to the original.
Now let's look at a 50 Hz signal (turn on your bass face). We need to zoom out a bit to see
full 50 Hz cycles:
The original signal and the delayed one overlap almost exactly! For a lower
frequency, the one-sample delay means almost nothing (since the waveform is
varying so slowly), and thus, in this case, the resulting signal is amplified,
not dampened. (The signal has changed phase here, too actually exactly as much
in terms of real time but we don't really see it, because we've zoomed out.)
Real signals are not pure sines, but they can be seen as sums of many sines
(another fundamental DSP result), and since filtering is a linear operation,
it affects those sines independently. In other words, we now have a very
simple filter that will amplify low frequencies and dampen high frequencies
(and delay the entire signal a little bit). We can do this for all
frequencies from 0 to 24000 Hz; let's ask Octave to do it for us:
(Of course, in a real filter, we'd probably multiply the result with 0.5
to leave the bass untouched instead of boosting it, but it doesn't really
change anything. A real filter would have a lot more coefficients, though,
and they wouldn't all be the same!)
Let's now turn to a problem that will at first seem different: Combining
audio from multiple different time sources. For instance, when mixing video,
you could have input from two different cameras or sounds card and would want
to combine them (say, a source playing music and then some audience sound
from a camera). However, unless you are lucky enough to have a professional-grade setup
where everything runs off the same clock (and separate clock source cables
run to every device), they won't be in sync; sample clocks are good, but they are
not perfect, and they have e.g. some temperature variance. Say we have really
good clocks and they only differ by 0.01%; this means that after an hour of
streaming, we have 360 ms delay, completely ruining lip sync!
This means we'll need to resample at least one of the sources to match the
other; that is, play one of them faster or slower than it came in originally.
There are two problems here: How do you determine how much to resample
the signals, and how do we resample them?
The former is a difficult problem in its own right; about every algorithm
not backed in solid control theory
is doomed to fail in one way or another, and when they fail, it's extremely
annoying to listen to. Nageru follows 
One criminally-unknown new UNIX tool is 
The big 1.0.0 is here! Following the unsurpassed lead of the 
There s a 
Please note that the environment it runs on is deployment . The backend server it uses is the great Starman, also by the great Miyagawa.
Now, if you add or change dependencies on Makefile.PL, next time you push, those will get updated.
Very cool, right? :)
(Some) people seem to be anxious to know what I m doing next, and my answer is, go mind your own fucking business. However, life is short and I would love to do any of the following:
Oh, also: he discovered key combinations that did things that were unsurprising to me (like taking the screen grab above) and also things that I'm still scratching my head about (like causing a prompt on the screen that said: "Downloading shockwave plugin." No thanks. And, how did he do that?
The gig poster
Nano Kino 7"
