wiki:NetDB/NextBackend

Version 9 (modified by hottuna, 6 years ago) (diff)

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General P2P networks

Name Search horizon* Comments
Gnutella Limited
Gnutella2 Limited


  • Search horizon describes how much the network that can be searched from a certain position in the network graph. Limited search horizon means that a search from one part of the network won't necessarily find results from another part of the network.

DHTs

DHTs are a good alternative due to O(log n) lookup time and a unlimited search horizon. But have serious issues when it comes to being robust against attacks.

Name Search horizon* Lookup steps Mutable data Comments
Kademlia Unlimited Min:O(log,,2 n) Max: O(log2b n) No Is susceptible to sybil and eclipse attacks.*
Freenet Unlimited O(log2 n) [2]No Does not handle mutable data gracefully?
Choord Unlimited No Is highly susceptible to sybil and eclipse attacks.*
Pastry Unlimited No Is highly susceptible to sybil and eclipse attacks.*


  • Kademlia is less susceptible to eclipse attacks. "For one thing, it is difficult to affect the routing tables of a Kademlia node, as each node tends to keep only highly available peers in its routing table. This increases the required costs for an attacker to convince honest nodes to link to the compromised nodes. Similarly, Kademlia uses iterative routing, exploring multiple nodes at each step, making routing less dependent on specific nodes and thus less vulnerable to attacks." [1]

Kademlia lookups can be optimized by enlarging how many bits of IDs b, that are considered for each bucket. With b > 1 lookup steps would be decreased from O(log2 n) to O(log2b n) but the number of buckets would be increased from bits_in_id(ID) to bits_in_id(ID)2. [2]


[1] A Survey of DHT Security Techniques http://www.globule.org/publi/SDST_acmcs2009.pdf
[2] Kademlia: A Peer-to-peer information system based on the XOR Metric https://github.com/ntoll/drogulus/raw/master/docs/papers/maymounkov-kademlia-lncs.pdf
[3] Searching in a Small World https://freenetproject.org/papers/lic.pdf

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