P2P and Open Source Flashcards
what is P2P
a network that relies on computing power and bandwidth of the participants
What are the different types of P2P networks
Full P2P (Decentralised)
- peers act as clients and servers
- no central server managing the network
- no central router
- e.g GNUtella
Centralised (Star)
- central server keeps info about peers and responds to requests for that information
- peers host info and upload it to server
- e.g. Napster
Super nodes (Flower)
- many servers
- e.g. BitTorrent
How does Napster work?
client server is used to locate files
files are downloaded directly from peers
centralised star P2P network
client-server architecture
- single logical point of failure
- potential for congestion
- napster in control
- no security, no anonymity, no authentication
what is the most efficient structure?
the star is most efficient but weakest in terms of law enforcement - server can just be traced and company shut down
full P2P is least efficient
flower network/supernode is best compromise
what are the advantages of P2P networks?
- sharing
- collaboration
- foundations of the internet
what is free-riding and what can be done?
when users download but do not upload.
fundamental tension between individual rationality and collective welfare
rational peers freeride e.g. 66% of GNUtella peers share no files
Incentives, rely on altruism, enforcement
What are indirect and direct reciprocity used as incentives?
Direct reciprocity - repeat interaction between peers encourages reciprocity
e.g. BitTorrient
indirect reciprocity - peers earn reputation via cooperation e.g. reputable peers receive preferential treatment.
give examples of attacks on P2P networks
- poisoning attacks - submitting a file with a different name - if people want to share their file that noone wants to download
- companies do this - they distribute files with the wrong name to put people off
- denial of service attack - too many requests at the same time slows down/halts service. Used as a hacking attempt or in protest.
- defection attacks - free riding, not uploading anything
- malware in the p2p network itself
can be countered by using encryption
what is open source?
a collaborative development, where the source code (the blueprint, the formula, the recipe, etc.) as well as any subsequent modification and improvement are disclosed, not only to the members of the project, but to the whole community.
advantages and disadvantages of open source
+
free or low cost
substantial crowds of developers
- IPR infringement
Business models for OS
- optimisation strategy - create two layers of product. Usually free version and premium version
- dual license strategy - e.g. software is free but users need to purchase hardware
- consultancy services, or both maintenance and consultancy
- complementary services e.g. RedHat - does not only supply the open source software, but also complementary services: easy to use installation assistant, support etc
Is android open?
apache 2.0 software license that insures the code can be modified, reused and distributed
based on linux, which is open source
a community development approach
assurance the user has total freedom over the device and software
a community development approach
partial freedom
can’t see what’s happening behind the scenes, nor can small developers contribute to the project in any meaningful way
detail the new anti-piracy Copyright Alert System
MPAA (Motion Picture Association of America) and RIAA (Recording Industry Association of America) has collaborated with ISPs.
ISPs monitor the P2P file-sharing sites
when they catch people uploading/downloading, they record IP address
Up to 6 warnings before punishment
Punishment at final stage may be a temporary suspension from the internet or reduced internet speeds.
Outline PIPA and SOPA
The Stop Online Piracy Act (Sopa) is the bill being considered by the House of Representatives.
The Protect Intellectual Property Act (Pipa) is the parallel bill being considered by the Senate.
The proposed legislation is designed to tackle online piracy, with particular emphasis on illegal copies of films and other forms of media hosted on foreign servers.
The bills propose that anyone found guilty of streaming copyrighted content without permission 10 or more times within six months should face up to five years in jail.
The US government and rights holders would have the right to seek court orders against any site accused of “enabling or facilitating” piracy. This could theoretically involve an entire website being shut down because it contains a link to a suspect site.
Opposition from Google, Wikipedia, Reddit
Act is postponed
Example of BitTorrrent and direct reciprocity
The BitTorrent file-sharing system went beyond currency and reputation, and adopted an incentive mechanism based on barter. By partitioning large files such as movies and software binaries into small chunks, file-sharing using the BitTorrent protocol necessitates repeat interactions among peers, allowing cooperation to flourish based on direct reciprocity rather than indirect reciprocity.
