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- Centralized Network: The first generation architecture made use of number centralized
index servers that maintained a database of all the content on the network and clients logged on at any one time.
The database is updated whenever a client logs on to or off the network.
- Decentralized/Distributed Network: Instead of central servers deployed on a network, a
user's PC acts an integral part of the network performing the tasks of both an index server, searching locally held
resources, and as a router, relaying queries between peers.
- The query protocol works on a "waterfall" principle: Each peer is directly connected to
a number of other peers. This generates very large volumes of search traffic (chatter) as all search requests and
responses are relayed from each node to it's peers. From a Service Provider's perspective, while the queries are
small in size this protocol generates large amounts of upstream and downstream, off-network traffic
- Hybrid Networks: This hybrid architecture deploys a hierarchical structure by establishing
a backbone network of SuperNodes (or UltraPeers) that take on the characteristics of a central index server. When a client
logs on to the network, it makes a direct connection to a single SuperNode which gathers and stores information about
peer and content available for sharing.
- Dynamic Port Selection: Peer-to-Peer protocols have used fixed ports, however, many
P2P have introduced protocols that dynamically select a port for transfers, normally these ports are in the range
between 1024-4000. In some instances, traffic is even being masked by using ports normally associated with other main
stream applications such as ports 80 and 25 - the reserve of HTTP and SMTP traffic.
- Bi-Directional Downloads: eDonkey and BitTorrent have seen the introduction of bi-directional
streaming of download traffic. This enables multiple, simultaneous downloads and uploads of a single file and/or multiple,
simultaneous downloads of an element of a single file. Most traditional architectures require the object to be fully
downloaded before uploading can begin. The Bi-Directional downloads enables a single file to be downloaded by multiple
subscribers and/ or multiple subscribers to download the same file in fragments from multiple sources/clients.
- Anonymous distributed networks: The new generation of P2P networks offers completely anonymous
participation using many advanced techniques such as proxy anonymizers, encryption, tunneling and other anonymous and trusted
peer techniques. The user in those networks can not be identified. When encryption is used, not even the content being
transmitted (i.e., an audio or video file) can be identified. Below is a summary description of some of the 3rd generation
anonymous P2P networks.
- I2P: I2P is a scalable, self organizing, and resilient anonymous message based network layer,
upon which any number of different anonymity or security conscious applications can operate. Each application can make its
own anonymity, latency, and throughput tradeoffs without worrying about the proper implementation of a free route mix network ,
allowing it to obscure its activity by blending with the activities of a larger anonymity set of users running on the I2P
network. Applications available already provide the full range of typical Internet activities – i.e., anonymous web
browsing and anonymous web hosting. There are a great many other applications working on anonymous communication:
- Morphmix and Tarzan: Morphmix and Tarzan are both fully distributed, self-organizing
peer to peer networks of anonymizing proxy relays, allowing people to tunnel through a low latency mix network.
- TOR / Onion Routing: TOR and Onion Routing are anonymizing proxy networks related to an
Office of Naval Research information hiding project , that allow people to tunnel out through their low latency mix network.
- Mixminion / Mixmaster: Mixminion and Mixmaster are networks to support anonymous
email against powerful adversaries.
- Freenet: Freenet is a fully distributed, peer to peer anonymous publishing network,
offering secure ways to store and host data, as well as some approaches attempting to address the loads of a flash flood
- JAP: JAP (Java Anonymous Proxy) is a network of mix cascades for anonymizing web requests.
It uses a few centralized participants in the cascade to blend and mix requests from clients through a sequence of
participant nodes (the cascade) before proxying out onto the web
- MUTE / AntsP2P: Both of these systems work through the same basic “antnet” routing,
providing some degree of anonymity based on the threat model of providing plausible deniability against a simple
non-colluding adversary.
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