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

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2.3 Motivation: Freedom of speech / Freedom of the press The whole situation of free speech and a free press could be summarized by a famous quote of American journalist A. J. Liebling: Freedom of the press is guaranteed only to those who own one. While free speech and a free press are known to be a cornerstone of most modern civi- lizations (nearly every country in the western hemisphere has freedom of speech/freedom of the press protected by its constitution ), recent tendencies like the patriot act in the USA or the pressure on the media in Russia have shown that a lot of societies tend to trade freedom for a (supposed) feeling of security in times of terror or aren’t able to defend themselves against their power-hungry leaders. With fear-mongering media and overzealous government agencies all over the world, it might be a good idea to have some form of censorship resistant network which allows publishing and receiving of papers and articles in an anonymous manner and still allow the public to access the information within this network. Moreover, it should be possible to allow sharing of textual content as well as video and audio. This tends to be difficult as file sizes of video and audio content are pretty big when compared to simple textual content. 3 Technical Networking Background 3.1 Namespaces To really understand the patterns which allow accessing networks in an anonymous way, it is first necessary to understand the basic concepts of networks and the unique characteristics a PC possesses in any given network. There basically are two things that identify a PC in a network: • The NICs 1 MAC 2 address (e.g. "00:17:cb:a5:7c:4f") • The IP address used by the PC to communicate (e.g. "80.131.43.29") Although a MAC address should be unique to a NIC and an IP addresses should be unique on a network, both of them can be altered. Both of them can be spoofed to imitate other Clients or simply disguise the own identity. Spoofing the MAC address of another client that is connected to the same switch will usually lead to something called 1 NIC: Network Interface Card 2 MAC: Media Access Layer 3
"MAC flapping" and make proper communication impossible. Also: MAC Addresses are only of concern in the same collision domain. As soon as a Network-Packet is being transfered over a gateway to another network, the MAC Address of the source node will be overwritten by the MAC address of the gateway. As this is the case on the internet, we can mainly concentrate on the IP address as a means to identify a Computer on the internet. There are other means of identifying a Computer within a group of peers, this will be covered in Chapter 3.3, but first, we have to take a look at how the data is being transfered over the Internet. 3.2 Routing A main factor in the whole concept of anonymity is the way a file takes when traveling through the Internet. There are some patterns that allow an anonymous exchange of files when being on the same physical network, but that is usually not a "real-world" case and will not be discussed in this paper. When sending a file from one edge of the Internet to another, you usually end up going through several different stations in between. Let’s look at the usual "direct way" a TCP/IP packet will go by when traveling from the Stuttgart Media University to the MIT University to give a certain understanding of who is involved in the exchange of a simple IP packet: The tool (traceroute) visualizes the path a packet will usually take to Figure 1: IP hops from Germany to the US reach its target. As you can see in the trace log, there are 18 different nodes involved in the transfer of a packet from stuttgart to MIT. While this is necessary to keep the internet stable in the event of outages, it also increases the numbers of possibilities of a 4
Page 1 and 2: The current state of anonymous file
Page 3 and 4: Declaration of originality I hereby
Page 5 and 6: 5.2 The Brightnet pattern . . . . .
Page 7: 2 Basic concept of anonymity in fil
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
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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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