[bittorrent] question about bittorent traffic

David P. Mott dpmott at sep.com
Wed Oct 11 13:21:54 EDT 2006


It doesn't matter who initiates the connection, or for what reason.  Once 
a connection is established, either side can request a packet.

You should double-check your packet trace and determine if a request was 
sent (since you did not note that in your description).  If clients are 
connecting and then sending *unsolicited* chunks, then that's bad and 
should be seen as an attempted denial of service attack (it wastes the 
peer's bandwidth).

Note: I couldn't quote you on the rules that seeders use to connect to the 
swarm; they are well within their rights to sit back and only accept 
connections, or they could actively connect to leechers.  As I said above, 
the reason doesn't matter -- requests can flow either way once a 
connection is established.

-dpmott

> From: "Demetres Antoniades" <deanton at gmail.com>
>
> Hello,
>
> I am trying to understand when a bittorrent client will initiate a 
> connection to another client in order to upload a chunk of the file. I 
> would expect that the initiator of the connection would be the 
> interested leecher but in a packet trace that I have I see the uploader 
> initiating the connection sending the handshake message "19BitTorrent 
> Protocol" and after he gets a response it uploads a chunk of the file. 
> Does anyone know if this is the default way of sharing chunks or if this 
> happens under certain circumstances. I would expect this to happen when 
> the uploader is behind a NAT and so the downloader can not access him. 
> But in my experiment this is not the case.
>
> Thanks,
> Demetres



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