The current state of anonymous file-sharing - Marc's Blog

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Contents 1 Different needs for anonymity 1 2 Basic concept of anonymity in file-sharing 2 2.1 What is there to know about me? . . . . . . . . . . . . . . . . . . . . . . 2 2.2 The wrong place at the wrong time . . . . . . . . . . . . . . . . . . . . . 2 2.3 Motivation: Freedom of speech / Freedom of the press . . . . . . . . . . 3 3 Technical Networking Background 3 3.1 Namespaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2 Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.3 Identification throughout the OSI layers . . . . . . . . . . . . . . . . . . 5 4 Current popular file-sharing-protocols 7 4.1 A small history of file-sharing . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1.1 The beginning: Server Based . . . . . . . . . . . . . . . . . . . . . 7 4.1.2 The evolution: Centralized Peer-to-Peer . . . . . . . . . . . . . . 8 4.1.3 The current state: Decentralized Peer-to-Peer . . . . . . . . . . . 8 4.1.4 The new kid on the block: Structured Peer-to-Peer networks . . . 9 4.1.5 The amount of data . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.2 Bittorrent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2.1 Roles in a Bittorrent network . . . . . . . . . . . . . . . . . . . . 12 4.2.2 Creating a network . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.2.3 Downloading/Uploading a file . . . . . . . . . . . . . . . . . . . . 13 4.2.4 Superseeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.3 eDonkey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3.1 Joining the network . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3.2 File identification . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3.3 Searching the network . . . . . . . . . . . . . . . . . . . . . . . . 16 4.3.4 Downloading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.4 Gnutella . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.4.1 Joining the network . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.4.2 Scalability problems in the Gnutella Network . . . . . . . . . . . 21 4.4.3 QRP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.4.4 Dynamic Querying . . . . . . . . . . . . . . . . . . . . . . . . . . 23 4.5 Anonymity in the current file-sharing protocols . . . . . . . . . . . . . . 24 4.5.1 Bittorrent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.5.2 eDonkey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4.5.3 Gnutella . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 5 Patterns supporting anonymity 29 5.1 The Darknet pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 5.1.1 Extending Darknets - Turtle Hopping . . . . . . . . . . . . . . . . 30 IV
5.2 The Brightnet pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 5.2.1 the legal situation of brightnets . . . . . . . . . . . . . . . . . . . 32 5.3 Proxy chaining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 5.3.1 What is a proxy server? . . . . . . . . . . . . . . . . . . . . . . . 33 5.3.2 How can I create a network out of this? (aka: the proxy chaining pattern) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 5.3.3 How does this improve anonymity? . . . . . . . . . . . . . . . . . 34 5.3.4 legal implications of being a proxy . . . . . . . . . . . . . . . . . 35 5.3.5 illegal content stored on a node (child pornography as an example) 36 5.3.6 copyright infringing content . . . . . . . . . . . . . . . . . . . . . 37 5.4 Hop to Hop / End to End Encyrption . . . . . . . . . . . . . . . . . . . . 38 5.4.1 Hop to Hop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 5.4.2 End to End . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 5.4.3 Problems with end to end encryption in anonymous networks . . 39 6 Current software-implementations 41 6.1 OFF- the owner free filesystem - a brightnet . . . . . . . . . . . . . . . . 41 6.1.1 Structure of the network . . . . . . . . . . . . . . . . . . . . . . . 41 6.1.2 Cache and Bucket . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 6.1.3 Bootstrapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 6.1.4 Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 6.1.5 Downloading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 6.1.6 Sharing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 6.1.7 Scaling OFF under load . . . . . . . . . . . . . . . . . . . . . . . 46 6.2 Retroshare - a friend to friend network . . . . . . . . . . . . . . . . . . . 49 6.2.1 Bootstrapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 6.2.2 Encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 6.3 Stealthnet - Proxychaining . . . . . . . . . . . . . . . . . . . . . . . . . . 49 6.3.1 Bootstrapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.3.2 Encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.3.3 Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.3.4 "Stealthnet decloaked" . . . . . . . . . . . . . . . . . . . . . . . . 51 7 Attack-Patterns on anonymity 53 7.1 Attacks on communication channel . . . . . . . . . . . . . . . . . . . . . 53 7.1.1 Denial of Service . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 7.2 Attacks on Anonymity of peers . . . . . . . . . . . . . . . . . . . . . . . 54 7.2.1 Passive Logging Attacks . . . . . . . . . . . . . . . . . . . . . . . 54 7.2.2 Passive Logging: The Intersection Attack . . . . . . . . . . . . . . 55 7.2.3 Passive Logging: Flow Correlation Attacks . . . . . . . . . . . . . 55 7.2.4 Active Logging: Surrounding a node . . . . . . . . . . . . . . . . 56 V
Page 1 and 2: The current state of anonymous file
Page 3: Declaration of originality I hereby
Page 7 and 8: 2 Basic concept of anonymity in fil
Page 9 and 10: "MAC flapping" and make proper comm
Page 11 and 12: Physical Link Layer: Anonymity in t
Page 13 and 14: in email attachments until today).
Page 15 and 16: • structured search and content d
Page 17 and 18: about a "network" in context with B
Page 19 and 20: 4.2.4 Superseeding Figure 5: schema
Page 21 and 22: ed2k://|file||||/ a real-world exam
Page 23 and 24: ased on the property of societies,
Page 25 and 26: cliques. A little example would be,
Page 27 and 28: 3. An ultrapeer connected down to o
Page 29 and 30: This step is being called the "prob
Page 31 and 32: To keep the ISP from detecting this
Page 33 and 34: and the amount of traffic generated
Page 35 and 36: This might help to solve the proble
Page 37 and 38: it, has either no specific meaning
Page 39 and 40: This means that the packets being s
Page 41 and 42: 2. Die Übermittlung von Informatio
Page 43 and 44: 2. Der Versuch ist strafbar Another
Page 45 and 46: Figure 10: End to End encryption is
Page 47 and 48: identifies itself to other nodes se
Page 49 and 50: This will tell the client the follo
Page 51 and 52: passed out to trusted nodes (you ca
Page 53 and 54: and thus subject to legal attack, O
Page 55 and 56:
The application was designed to be
Page 57 and 58:
• The fact that the client used t
Page 59 and 60:
filtered by their networking equipm
Page 61 and 62:
7.2.4 Active Logging: Surrounding a
Page 63 and 64:
References [1] Arvin Nayaranan and
Page 65:
http://www.medialab.tfe.umu.se/publ
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