LIS508 almost last lecture: Privacy and Ethics Thomas Krichel

The unethical network There are a lot of ethical issues arising in computer networks! Here we list a few.

Offensive Speech WWW and other network installations are full of speech that offends some –views on religion and politics –sexually explicit material –spam Are Internet Service Providers (ISPs) reliable for contents? Are they allowed to restrict contents?

Government snooping FBI has installed a system at many ISPs to snoop for any interesting contents. Originally called carnivore, now DCS1000. But fourth amendment prohibit searches without a search warrant. At the world summit for the information society, developing countries have pushed for UN control of the Internet.

Private snooping Web providers have cookies installed to recognize users of the some machine. If this is a home machine, behavior of a user may be quite traceable. But, of course, it can be used to provide convenient features that overcome the stateless nature of http.

Illegal copying Some copyright holders view the Internet as a giant copying machine. They may be right when it comes to file sharing. File sharing operates on peer-to-peer networks exchanging information.

Peer-to-Peer (P2P) Most Internet services are based on a client/server architecture. In a P2P architecture, users run clients that also run as servers, called "servents". But we can stick to client/server way of terminology –You act as a client when I want something –You act as a server when you give something

Napster Napster is sometimes referred to as a p2p network. This is not quite true. Napster ran a central server. You connected to that server and announced what files you had to share. Every search was conducted on the dataset assembled at the central server. Connections to download files where done between peer machines only!

end of Napster Napster argued since it was only involved in collecting the information about files available, it was legal. Napster never shared any illegal file. The courts thought otherwise. It was shut down. Napster network died without a central machine. To enable true piracy, we need a truly distributed system.

gnutella protocol This protocol underlies much of the current file-sharing activity on the Internet. It is based on TCP/IP and http! A file sharing network (fsn) is a bunch of machines that exchange files using gnutella. To connect to a gnutella network, you need the IP address of one single machine that is already part of the network.

connection to a fns Once you establish connection to the first servent, you announce your presence. The first servent will pass on that message to all the servents that it is connected to, and so on. These servents all reply with data about themselves –how many files it is sharing –how many kilo bytes the files take up This already adds up to a lot of traffic!

time to live Every gnutella message has a time to live (ttl). It is decremented every time it passes at a servent. The TTL is usually quite small. It can be arbitrarily reduced by servents. The number of servents that the packet has already been rooted to is also noted.

detail on the message MessageID16 bytes ID FunctionID1 byte function of packet –search –connection announcement (initialization), etc. RemainingTTL1 byteTTL left to this packet HopsTaken1 bytenumber of servents this packet has already been routed through DataLength4 bytessize of the remaining data in the packet (no need to remember for quiz)

example scenario Alice starts a servent. Knows Charlie's IP and send him an init packet. Charlie gets it and routes it to Bob and Eve. They pass it on further and so on, until TTL is reached. Charlie sends his file data to Alice. Charlie gets responses from Bob and Eve, sends it to Alice… Everyone only knows about the servents that they are connected to.

searches When you do a search, it is passed on from servent to servent through the fsn. Servents have their own rule how to repond to queries. –If you search for '.mp3' a servent may only look for a file '.mp3' a servent may look for all files ending with.mp3 –Servents may respond with a truncated results set. Searches are public, most fsn software has a search monitor.

downloading to establish downloads the servents use http. this is a well-established protocol with a good code base. Thus everyone who is connected to a file sharing network run a web server!

ease to infringe Clearly all the traffic on a fsn, with current technology, can be observed. But the infringement is so massive that it appears difficult to clamp down on. The easy to infringe is technological. RIAA have sued. They reach the tippy top of the iceberg, with the hope to dissuade.

copyright holders are scared ISPs can keep track who has what IP at a given moment. Some block the ports that are used for file sharing. Copyright holders have demanded these lists. This is a violation of customer privacy.

Freenet This is as different file sharing system that is still under development. It aims: –To allow people to distribute material anonymously. –To allow people to retrieve material anonymously. –To make the removal of material almost insuperably difficult. –To operate without central control. Ethics are more political.

operation of freenet Searches are only passed to one other servent, which pass it on. After no positive response from that chain, another servent is tried. But the entire document sought is passed along, unless it is too large Servents keep caches of popular documents until no one asks for it for a long time. popular documents frequent and close to users.

searching on freenet You basically can not search on freenet. Each document has an identifier. The identifier and the document can not be changed. This will make it difficult to use it on its own as a device for people to exchange copyrighted material.

Thank you for your attention!