[p2p-hackers] UDP Keep-alive

Eugen Leitl eugen at leitl.org
Wed Jan 12 13:19:01 UTC 2005

On Tue, Jan 11, 2005 at 10:13:48PM +0100, Eugen Leitl wrote:
> On Tue, Jan 11, 2005 at 01:01:33PM -0800, coderman wrote:
> > Most NAT's appear to give a 1-5 minute timeout since last
> > packet seen.  It would be nice to find a market summary of
> > various NAT behaviors.  Anyone know of such a thing?
> Here's a data point: I've spent the better part of the day trying to remove
> default NAT (60 sec TCP, 180 sec UDP) idle connection decay from a Draytek
> Vigor 2900G with latest firmware.
> To no avail, had to send email to support (probably, /dev/null).
> Proprietary NAT boxes are evil, period.

I take that back, at least partly. Here's what Draytek support told me: 

Thanks for your e-mail.
Actually, 60 seconds idle time of TCP is for uncomplete TCP connection, as we
know, TCP connection has 3-way handshakes menchanism, when the TCP
+SYN send out, a session established, if the 3-way handshakes fail to
complete, router will delete it after 60 seconds idle.
But if the TCP 3-way handshakes is completed, the session should be
'persistent', it is only removed if it idles for 24 hours. For your scenario,
+when your browser call the cgi-bin, it's certainly after tcp connection
established, so there should be no problems.
Do you mean you have encountered problems when you try to call the cgi-bin?
Or you haven't meet problem but just want to prevent potential issue?

We'll look forward your further news.

I'm reasonably certain it's a firmware bug, or maybe a misconfiguration.
For time being I've switched over to Linksys WRT54G with Alchemy-6.0-RC5a
v3.01.3.8sv, and the problem has gone away.
> Which reminds me (since I've got my IPv6 subnet approved a few days ago):
> what's p2p application situation for IPv6? Can anyone give a brief summary?

Eugen* Leitl <a href="http://leitl.org">leitl</a>
ICBM: 48.07078, 11.61144            http://www.leitl.org
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http://moleculardevices.org         http://nanomachines.net
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