[bittorrent] Tracker is forgetting/currupting my port number

Justin Cormack justin at street-vision.com
Thu May 25 09:46:33 EDT 2006


Trackers hand out out of date port numbers for a long period, due to
the timeouts.

On Thu, 2006-05-25 at 09:23 -0400, Thad Ward wrote:
> An idea as to what might be happening has come to me recently. I think
> that these random ports you're seeing are from peers attempting to send
> data to your old outgoing port number. When your client needs to connect
> out, it uses some port number that is not currently in use (usually) between
> 1025 and 65535. Apparently, clients send DHT communication via UDP to the
> port they were talking to you on for the TCP peer connection. I think
> that the DHT-capable clients should only be sending the UDP packets if
> they know that you're listening on that port (ie, they connected to you,
> rather than the other way around) from their DHT port. This way,
> everyone can be sure the DHT packets are going where they should, and
> people without ports forwarded will still get their DHT packets, as most
> consumer routers will auto-forward UDP packets from a IP/port that it
> saw an outbound packet to. (Although it is likely to mangle the source
> port of the packet when it does NAT, anyway. hmm..)
> 
> Anyway, that's what I think might be going on with these packets you're
> seeing.
> 
> On Wed, Apr 26, 2006 at 12:17:19PM +1200, Mark Curly wrote:
> > Since these are UDP packets, I now believe this is a problem with DHT.
> > 
> > ----- Original Message ----- 
> > From: "Mark Curly" <markcurly at hotmail.com>
> > To: <bittorrent at lists.ibiblio.org>
> > Sent: Saturday, April 15, 2006 5:24 PM
> > Subject: Tracker is forgetting/currupting my port number
> > 
> > 
> > > I think I've found a bug in a tracker.
> > >
> > > I setup my client and configure my port number.
> > > I connect to a few trackers and download a few files.
> > > I exit my client.
> > >
> > > Then my firewall shows incoming refused UDP packets to the target torrent
> > > port, from many source IPs.
> > > All very good and expected: "Afterglow".
> > >
> > > Then several hours later it starts showing incoming refused packets to a
> > > different port, from many source IPs.
> > > What?
> > > Then again several hours later, same again with a different target port.
> > >
> > > It looks like the tracker has forgotten/mangled my bittorrent port number,
> > > and is telling clients the wrong port.
> > > Those clients then 'ping' (a bencoded ping) me, but with the wrong target
> > > port number.
> > > (I have a static IP BTW.)
> > >
> > > I can't easily tell which torrent or tracker has the problem, but maybe
> > > someone smarter than me could help me identify the tracker, or put me
> > right
> > > on what is happening?
> > >
> > > To be clear, my concern is just the (apparent) bug in the software used by
> > > that tracker, and other trackers.
> > > I could care less that I'm getting pinged for that particular torrent: my
> > > firewall just throws that stuff away.
> > >
> > > If it is too difficult to track down the tracker and what software it
> > might
> > > be using, then just ignore me :-)
> > >
> > > Thanks,
> > > Curly
> > >
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> > 
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