[tor-dev] [flashproxy] Not running using gnash

[David Fifield]

On Fri, Dec 23, 2011 at 01:00:01PM -0300, Mauricio Pasquier Juan wrote:
> On Thu, Dec 22, 2011 at 07:31:59PM -0800, David Fifield wrote:
> > On Thu, Dec 22, 2011 at 03:38:29PM +0100, Okhin wrote:
> > > Hello,
> > > 
> > > I was trying to run flashproxy using gnash following the RTMFP part of
> > > the tutorial located here:
> > > https://gitweb.torproject.org/flashproxy.git/blob/HEAD:/README
> > > 
> > > I do not use the gnash-plugin embedded in a browser, but the CLI tool
> > > gnash packaged with debian (and invoking it like this, as a standard
> > > user: gnash swfcat.swf -p client=1 -p debug=1
> > 
> > Thank you for testing this and for the thorough report. Unfortunately
> > I'm not surprised that it doesn't work with Gnash. I don't think Gnash
> > has some of the features we use, and probably doesn't have RTMFP, which
> > has only been partially reverse-engineered in another project. Some log
> > messages suggest this:
> 
> If the only reason to use flash is RTMFP, maybe it can be replaced with this
> technique: http://samy.pl/pwnat/ (if I didn't misunderstood the architecture of
> flashproxy)

Yes, the only reason to use Flash on the client is for RTMFP, and the
only reason to use RTMFP is to get across a NAT. I looked a pwnat and
didn't think it would work in this case, because a flash proxy doesn't
have raw socket access to send a Time Exceeded message. I could be
working under incorrect assumptions, though.

Long ago I wrote a very crude NAT puncher that doesn't require an
intermediary. It uses birthday collisions between randomly generated UDP
port numbers.
https://gitweb.torproject.org/flashproxy.git/blob/9c471b4b99d07c8db197d15fe6eb4d37d85b0ea6:/nat-birthday.py
We gave up on it because (1) it requires both client and server to know
each other's address in advance, (2) it takes a few hundred packets, and
(3) we don't have access to UDP sockets anyway, except through
abstractions like RTMFP.

> Anyway, if there is some javascript code to check, I'd like to help with that
> development.

There's no JavaScript yet, but we want to port the ActionScript (which
is similar). These are the primary source files:
https://gitweb.torproject.org/flashproxy.git/blob/HEAD:/swfcat.as
https://gitweb.torproject.org/flashproxy.git/blob/HEAD:/ProxyPair.as
I don't have any experience with JavaScript network programming yet, but
porting doesn't look too hard, as long as you get reasonable event
callbacks for things like reads.

David Fifield