Christian Grothoff transcribed 8.3K bytes: > Hi Philipp, > > Some answers inline below. > > On 04/18/2017 09:18 AM, Philipp wrote: > > Hello everyone, > > I am currently working on my master's thesis at the University of Ulm. > > As a part of my thesis, I performed a literature survey on some systems > > that offer anonymity properties in P2P environments, among them GNUnet. > > > > I have a few questions regarding GNUnet. I hope it is fine to post them > > here on the mailing list. Unfortunately, when visiting the FAQ website > > https://gnunet.org/faq-page I just get an emtpy page, so I couldn't > > figure out whether there are already answers posted to some of the > > questions I have.
Christian, do you know what happened to the page? It really is empty. If there was a page, we should get it back or delete the menu link. > > I would be very grateful for help on some of these topics. > > > > 1) In [1], it is mentioned that nodes observe the behavior of > > neighboring nodes. It also states that a node might pass files (or > > possbily blocks of a file) to other nodes depending on how trustworthy > > they seem. Are these trust values derived based on the scheme described > > in [2]? > > Nodes will pass blocks of files (never files) based on available > bandwidth (trying to keep their traffic profile constant). However, IF > a peer has earned trust ([2]) and IF that peer made a prioritized > request, nodes will prioritize such requests (possibly doing less work > for others, dropping other peer's blocks) over other requests from nodes > that either did not earn trust OR did not make a prioritized request. > Trust is lost/reduced/reassigned when making prioritized requests. > > > 2) As far as I understood, files that I want to publish are always > > placed on my local node and not actively distributed into the network. > > The files will be actively distributed into the network IF your > configuration allows it (CONTENT_PUSHING = YES). > > > I can, however, decide whether I want to generate a copy and place it in > > my local store in encrypted form or whether I just want to create the > > index and blocks are encrypted "on-the-fly" when requested. > > That's an orthogonal concept; indexing vs. insertion is about how > locally-published files are stored (kept in clear in FS or encrypted in > DB). This has no impact on the pushing strategy (see above). > > > In [3], the > > term "content migration" is used. Are blocks actively pushed to other > > nodes even without requests on them? > > Yes, see CONTENT_PUSHING and CONTENT_CACHING options. > > > 3) https://gnunet.org/file-sharing-concepts mentions a replication level > > for blocks. What exactly is the purpose for this and how does it affect > > replication? > > If you enable CONTENT_PUSHING, the peer will prioritize making > replication-level PUSH operations of each block of your file before > going back to making "random" pushes. Basically, it's a way to give new > blocks a 'push' in terms of visibility. > > > 4) In the GAP approach described in [4], a peer, say A, can decide to > > skip the source rewriting step. On the return path, the successor of A > > needs to communicate directly with the predecessor of A. However, GNUnet > > uses encrypted links. Does this imply that these nodes need to perform a > > session key exchange before being able to send the result along the > > return path? > > Yes. > > > 5) Taking a look at [3] or [4], the network is described as a rather > > unstructured P2P network. I know also about the DHT based R5N [5] which > > is a structured approach. How does these two play together in terms of > > network management? Are there separate routing tables and maintenance > > protocols? > > Yes, the DHT's routing table is separate from (anonymous) FS, and the > DHT uses R5N's topology maintenance while FS uses 'topology' (F2F, > gossip, etc.). However, these do interact some, as core-level encrypted > connections found by one may be used immediately by the other and vice > versa. > > > 6) I know R5N is currently used for non-anonymous file sharing. > > Indirectly via CADET, yes. > > > There is > > not really sender anonymity due to the hop counter that is used to > > determine when to switch from random to deterministic routing. > > Nope, it's worse as CADET explicitly identifies the end-points and > creates a multi-hope end-to-end encrypted communication channel. > > > Furthermore, packets are not intentionally delayed to impede traffic > > analysis. However, would it be possible to apply similar mechanisms just > > like in GAP and, e.g., replace the hop counter or use probabilistic > > behavir to achieve sender anonymity in R5N? > > The likelihood that a particular peer issues queries for a particular > key in a DHT is quite skewed; it'll be tricky to get this "right" for a > DHT, and I do not think your simple method works sufficiently well for > the DHT. For FS: see my comment on CADET. > > > 7) Does GNUnet use erasure codes to tolerate the loss of some of the > > blocks of a file? Or is a file unretrievable if a block is lost? > > We (still) do not use ECC. > > > 8) Are there any performance measurements in a scientific publication > > about GAP or GNUnets anonymous file sharing in general? > > AFAIK no. Initially our performance was always limited by database IO > (even for the largest setups we could manage), and for testbed-style > setups this would likely still be a problem today. Also, several people > said they would script some kind of "realistic behavior" for users (who > publishes/searches/downloads what), but AFAIK nobody ever actually > proposed (not to mention implemented) a good benchmark. > > > [1] Grothoff, Christian, et al. "The gnet whitepaper." Purdue University > > (2002). > > [2] Grothoff, Christian. "Resource allocation in peer-to-peer networks: > > An excess-based economic model." Wirtschaftsinformatik 45.3 (2003): > > 285-292. > > [3] Bennett, Krista, et al. "Gnunet-a truly anonymous networking > > infrastructure." In: Proc. Privacy Enhancing Technologies Workshop (PET. > > 2002. > > [4] Bennett, Krista, and Christian Grothoff. "GAP–practical anonymous > > networking." International Workshop on Privacy Enhancing Technologies. > > Springer Berlin Heidelberg, 2003. > > [5] Evans, Nathan S., and Christian Grothoff. "R5n: Randomized recursive > > routing for restricted-route networks." Network and System Security > > (NSS), 2011 5th International Conference on. IEEE, 2011. > > > > Best regards, > > Happy hacking! > > Christian > > _______________________________________________ > Help-gnunet mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/help-gnunet -- PGP and more: https://people.pragmatique.xyz/ng0/ _______________________________________________ Help-gnunet mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-gnunet
