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Glasnost: Results from tests for BitTorrent traffic blocking

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Almost 70,000 users from locations around the world have used our tool, Glasnost, to test whether their BitTorrent traffic is being manipulated. On this page, we present preliminary results from these tests. The tests were conducted between March 18th and October 20th, 2008.

We will update this page with more detailed results as we get more data from the tests. We also hope to uncover more cases of blocking as we refine our measurement tool and our analysis. So make sure to check back later. Alternately, you can stay up-to-date on our findings by subscribing to the glasnost-updates mailing list.

We have released the source code of our tool. You are welcome to download and inspect the code. Please contact us if you find any bugs or have questions, comments, or suggestions.

We published a paper on this work in the ACM Internet Measurement Conference 2008. It contains updated results up to July 25th, 2008 from more than 47,300 end users. You can download the paper in pdf format here.
You can find the older version of this page from 25.07.2008 here.

 

Table of contents
  1. How do we detect BitTorrent blocking by ISPs?
  2. Are ISPs blocking BitTorrent traffic?
  3. Details of blocked BitTorrent transfers
  4. Is BitTorrent blocked only during periods of network congestion?
  5. Are ISPs changing their BitTorrent blocking policies?

 

1. How do we detect BitTorrent blocking by ISPs?

At a high level, our test sets up a series of BitTorrent flows between an end user's host and our Glasnost test servers. We collect the packet trace for each flow on the server side, and we closely monitor both end points for any error conditions that might cause a flow to be aborted. If a flow is aborted by a control (RST) packet that was not sent by either of the end points, we report the flow as being blocked by some ISP along its path.

For more details on how we detect BitTorrent blocking, please click here.

 

2. Are ISPs blocking BitTorrent traffic?

Location of tested nodes

Note: This map was created using GeoLite data by MaxMind, available from http://www.maxmind.com/.

The map plots the geographic location of the 69,696 nodes that ran our BitTorrent tests. These hosts are distributed across 149 countries and 2,614 access ISPs. Hosts that found their BitTorrent transfers being blocked are marked in red. Circles represent multiple measurements from the same location; the bigger the circle the more the number of measurements from the same place.

Note: ISPs may throttle (rate-limit) BitTorrent traffic without blocking it. The results we present here are limited to hosts whose BitTorrent transfers to our servers are blocked, i.e., interrupted by RST packets generated by some ISP along the path. We are still actively investigating techniques to accurately detect throttling. So we do not report any results on rate-limiting BitTorrent traffic at this time and we do not mark such throttled hosts in red.

The table below shows for each country (a) the number of hosts that ran our test, (b) the number of hosts for which we detected BitTorrent blocking, (c) the number of distinct access ISPs from which our test was run, and (d) the number of these ISPs that contained one or more hosts for which we detected BitTorrent blocking.

Country# measured
hosts
# blocked
hosts
# measured
ISPs
# blocked
ISPs
Afghanistan1010
Albania5030
Algeria125030
American Samoa1010
Andorra3010
Antigua and Barbuda4010
Argentina7920320
Aruba2010
Australia11771661
Austria2440320
Azerbaijan2010
Bahamas2010
Bahrain5020
Bangladesh270160
Barbados12010
Belarus1010
Belgium2812171
Belize3010
Bhutan1010
Bolivia9050
Bosnia and Herzegovina12080
Botswana1010
Brazil1008741212
Brunei Darussalam7010
Bulgaria2130500
Cambodia4040
Canada5976151449
Chile13600230
China1717263
Colombia1540220
Costa Rica19020
Cote D'Ivoire1010
Croatia147070
Cyprus26060
Czech Republic860240
Denmark1710270
Dominica3010
Dominican Republic41020
Ecuador16080
Egypt49060
El Salvador14040
Equatorial Guinea1010
Estonia50050
Faroe Islands3020
Finland6674291
France5350240
French Guiana2010
French Polynesia1010
Gabon1010
Georgia1010
Germany20951641
Ghana3010
Gibraltar1010
Greece6438191
Guadeloupe1010
Guam13020
Guatemala16050
Guyana3010
Honduras11050
Hong Kong1900110
Hungary6891441
Iceland36040
India4831251
Indonesia490130
Iran, Islamic Republic of17090
Ireland3775253
Israel7753163
Italy21440600
Jamaica14131
Japan177501090
Jordan13040
Kazakhstan6020
Kenya1010
Korea, Republic of377101
Kuwait33782
Country# measured
hosts
# blocked
hosts
# measured
ISPs
# blocked
ISPs
Latvia370140
Lebanon10050
Liechtenstein3020
Lithuania1231221
Luxembourg22050
Macedonia19050
Malaysia62020123
Maldives4010
Malta22050
Marshall Islands1010
Martinique2020
Mauritius3020
Mexico5240220
Moldova, Republic of6020
Monaco1010
Mongolia1010
Montenegro4020
Morocco4020
Mozambique2020
Nepal1010
Netherlands12000350
Netherlands Antilles11151
New Zealand4032202
Nicaragua4020
Niger1010
Nigeria2020
Northern Mariana Islands4010
Norway5640280
Oman2020
Pakistan46080
Palestinian Territory13020
Panama30020
Paraguay17030
Peru71030
Philippines2900130
Poland1590400
Portugal6240200
Puerto Rico32261
Reunion5030
Romania3361451
Russian Federation860520
Saint Lucia1010
Saint Vincent and the Grenadines2010
San Marino2010
Saudi Arabia27191
Senegal1010
Serbia1940150
Seychelles1111
Singapore320101151
Slovakia580150
Slovenia650130
South Africa27090
Spain29861391
Sri Lanka19040
Sudan4030
Sweden4511351
Switzerland2910310
Taiwan18286373
Thailand1141121
Trinidad and Tobago12020
Tunisia7010
Turkey49050
Ukraine210160
United Arab Emirates23020
United Kingdom41119804
United States21622410076635
Uruguay29020
Vanuatu1010
Venezuela83050
Vietnam90040
Virgin Islands, U.S.3010
Yemen1010
Zambia1010
Zimbabwe1010
Total696954315261488

 

3. Details of blocked BitTorrent transfers

1. All hosts which observed blocking did so in the upstream direction (i.e., when the client host attempted to upload data to one of our Glasnost servers). Only a handful of hosts observed blocking for downstream BitTorrent transfers.

2. We found widespread blocking of BitTorrent transfers only in the U.S. and Singapore. Interestingly, even within these countries, most of the hosts that observed blocking belonged to a few large ISPs.

3. Both in the U.S. and in Singapore, all hosts that suffered BitTorrent blocking are located in cable ISPs. We did not see any blocking of BitTorrent transfers from DSL hosts in these countries.

Most (3,894 of 4,100) U.S. hosts that observed blocking are located in Comcast and Cox networks. In Singapore, all blocked hosts are connected using the StarHub network. While we did observe blocking for hosts in 88 other ISPs (35 of which are in the U.S.), we did not see widespread blocking of BitTorrent traffic for hosts in those ISPs.

The table below shows the details of BitTorrent blocking for Comcast, Cox, and StarHub. For each ISP, we show (a) the number of distinct hosts we measured, and (b) the number of these hosts for which we detected BitTorrent blocking.

ISP# measured
hosts
# blocked
hosts
Comcast62213263
Cox1510631
StarHub225101

 

4. Is BitTorrent blocked only during periods of network congestion?

Recently it has been reported that Comcast defended its BitTorrent blocking before FCC as a necessary practice that is done only during periods of heavy network traffic. It is widely known that network traffic exhibits a strongly diurnal pattern. So we analyzed our data to see if hosts in Comcast and Cox networks see fewer of their upstream transfers blocked during early morning or weekends (when network load is generally low) than during other times of the day.

The left graph below shows (a) the number of measurements to Comcast hosts at different hours of the day and (b) the percentage of these measurements for which we observed BitTorrent blocking. The percentage of blocked tests remains high at all times of the day. Our data suggests that the BitTorrent blocking is independent of the time of the day.
The right graph below shows that the percentage of blocked BitTorrent connections remains fairly high even during the weekends for Comcast hosts.

comcast    comcast

Similarly, the left graph below shows that Cox hosts suffer BitTorrent blocking at all times of the day. Note that the data for Cox is more noisy than Comcast, due to smaller number of measured hosts.
The right graph below shows that the percentage of blocked BitTorrent connections remains fairly high even during the weekends for Cox hosts.

cox    cox

 

5. Are ISPs changing their BitTorrent blocking policies?

The graphs below show how the percentage of blocked BitTorrent connections changed during the last 6 months for Comcast, Cox, and StarHub customers. We notice a significant reduction in blocked BitTorrent tests for all three ISPs.

Comcast    Cox    StarHub

 

Contact

We are researchers at the Max Planck Institute for Software Systems. Our research focuses on characterizing residential broadband networks and understanding their implications for the designers of future protocols and applications. In case you have questions about this tool or our research, please visit our network transparency project webpage or contact us via e-mail: broadband @at@ mpi-sws mpg de

Faculty   Students
* Krishna P. Gummadi
  * Marcel Dischinger
* Andreas Haeberlen
* Alan Mislove