[tahoe-dev] uTP (low extra delay transport)

[Jack Lloyd]

On Tue, May 25, 2010 at 05:21:30PM -0700, Brian Parma wrote:
>   On 05/25/2010 03:44 PM, Jack Lloyd wrote:
> > On Tue, May 25, 2010 at 03:25:50PM -0700, Jeremy Fitzhardinge wrote:
> >    
> >>> Setting aside the ease of hole-punching with UDP,
> >>>        
> >> Is hole punching that much easier with UDP?  Does it help with the
> >> problem of getting in touch with a server behind a NAT gateway?
> >>      
> > Somewhat easier - many common NAT implementations will, upon seeing an
> > outbound UDP packet, set up a temporary forward from the originating
> > port to the machine behind the NAT.
> >
> >    
> Isn't that the idea behind this?
> http://samy.pl/pwnat/

This seems to be slightly sneakier. I'm not sure how necessary pwnat's
technique might be; most NATs I've encountered are perfectly OK with
opening ports if they think you want them open. It might be useful if
your NAT was particularly dumb or badly misconfigured, though.

(And in deploying things to work on the general Internet, it's
reasonably likely you'll encounter really dumn NAT implementations,
but I'm not even sure how relevent that is to Tahoe - how many people
are going to run storage servers behind a NAT and yet be
unable/unwilling to configure the NAT to forward the ports?)

-Jack