=== General P2P networks ===

|| '''Name''' || '''Search horizon*''' ||  '''Comments''' ||
|| Gnutella || Limited || ||
|| Gnutella2 || Limited || ||

[[BR]]
* 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(log2 n) Max: O(log2^b 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.* ||

[[BR]]
* 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] [[BR]]
** 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(log2^b n) but the number of buckets would be increased from bits_in_id(ID) to bits_in_id(ID)^2. [2] [[BR]]

[[BR]]

[1] A Survey of DHT Security Techniques http://www.globule.org/publi/SDST_acmcs2009.pdf [[BR]]
[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 [[BR]]
[3] Searching in a Small World https://freenetproject.org/papers/lic.pdf [[BR]]