[p2p-hackers] Work on NAT-friendly DHTs?

[Luca Piccarreta]

Forgive me, but I still don't have the picture clear.
One peer might need to contact another one:
1) Because it wants to ask something only that peer knows
    (e.g., get a file from that peer, or make a phone call)
2) Because it wants to ask something that other peers may know
    (e.g., routing informations)

I also made a distinction between routed network and non-routed network:
1) A peer exchanges messages with a small subset of nodes in the
overlay network. This small subset will manage delivery to unknown
peers
2) A peer exchanges search messages with possibly all peers in the network.
Search is done by interrogating a sequence of peers (determined by analyzing
peers answer) in order to reach the information desired (Kademlia)

I said that the scheme 2) can not take advantage of natted nodes for finding
informations. Well, of course it can... but it's not worth it. The UDP hole
opening traffic (or the relay traffic) requested to the non natted peers 
might
be more than the search traffic offloaded to the natted peers.
Is anyone really thinking of using UDP hole punching for key searches in
Kademlia-style networks?
In this case, can a rapid sketch be made?

For the moment I stick  in my position, that is a separation between a 
low bw
traffic for searches, managed by non natted peers, and a perhaps high bw
traffic for more advanced services (like file storage or even 
<key,value> storage)

I had to work with a NAT with a 5 seconds UDP hole timeout... how can one
think of opening more than a dozen of UDP holes if you have to keep them 
alive
so frequently? And what about NATs changing mapped ports whenever we
"forget" to keep alive to UDP hole?

I think that if effort is to be dedicated to the NAT issue, it is to be 
dedicated to
"many NAT layers" network schemes, in which a peer might have perhaps two or
three addresses...

Luca.

shudo at computer.org ha scritto:
>> From: Philip Matthews <philip_matthews at magma.ca>
>> Date: Thu, 26 Jan 2006 10:09:10 -0500
>>     
>
>   
>> I am wondering if anyone is aware of work on NAT-friendly DHT
>> algorithms?
>> In other words, a DHT algorithm that works with the peers are located
>> behind NATs.
>>     
>
> There will be 2 points of view. From the first standpoint, NAT
> traversal can be performed independently of a DHT algorithm. From
> another standpoint, an advanced DHT algorithm will be able to deal
> with such heterogeneity, in which even a NATted node can take a role
> on an overlay.
>
> As pointed out, it is common to introduce super-peers which host
> NATted peers. And an advanced algorithm, like HeterPastry, may adapt
> to such heterogeneous environemnt.
>
> UDP messaging service of Overlay Weaver implements UDP hole punching.
> The technique works with a lot of routers, but not all ones. The
> technique is not very reliable.
>
>   Overlay Weaver: An Overlay Construction Toolkit
>   http://overlayweaver.sf.net/
>
>
>   Kazuyuki Shudo	shudo at computer.org	http://www.shudo.net/
>
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