[JDEV] client timeouts

[Dave]

The "NAT hypothesis" is, in reality, the only way that an NAT router
knows to terminate a flow in its NAT table.  Because NAT is transparent
to its users, neither the client nor the server will (or can know to)
send the NAT router a notification that the connection has been ended
(and what about the case where your client is behind an NAT router which
itself is behind another NAT router?  If the client had some way of
alerting the closer NAT router, it'd still need to alert the other one,
or the closer one would have to alert the farther one - either way,
it's easy to tell that this kind of craziness would eliminate NAT's
major advantage: compatibility with existing hardware and software on
both sides of the network).  In other words, the NAT router must guess
on its own when a connection has been closed, and free up the ports used
so it doesn't run out.  (An easy way to DoS an NAT router from inside
the network is to open 64K connections to Yahoo! and/or Google and/or
AOL and/or MSN Web servers at the same time, and send a few bytes to
each every minute or so.)

 - Dave


PINSON Frederique FTRD/DMI/LAN wrote:
> 
> Hi !
> 
> I have few jabber servers in my intranet, and never get disconnected
> (unless particular problem).
> But when I used my account on my server outside the intranet, or the one
> I have on jabber.org, I often get disconnected...
> 
> This can validate the NAT hypothesis...
> 
> best regards, 
> Frederique
> 
> -----Message d'origine-----
> De : Matthias Wimmer [mailto:m at tthias.net]
> Envoye : lundi 1 juillet 2002 10:26
> A : jdev at jabber.org
> Objet : Re: [JDEV] client timeouts
> 
> 
> Hi Sean!
> 
> Sean Kirkby wrote:
> 
> >  Does the server need to see a bit of activity from the client 
> > regularly in order for the connection to stay alive?  The behavior in 
> > WinJab, Exodus, and JIM seem to indicate this.  Should my client 
> > emulate their behavior (i.e. sending "<sp><tab><sp>" every 60
> seconds)?
> 
> No, the server doesn't need this, it's done because of NAT-Routers. If 
> you are using a NAT-System to share an internet account between 
> different computers, this system forgets connections without activity 
> after some time.
> 
> 
> Tot kijk
>     Matthias
> 
> -- 
> Fon: +49-700 77007770		http://matthias-wimmer.de/
> Fax: +49-89 312 88654		jabber://mawis@charente.de
> 
> 
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