[tor-dev] [Stegotorus] Fundamental problem with ack/retransmission mechanism

[Jeroen Massar]

On 2013-06-18 11:52 , Vmon wrote:
> Hey Zack,
> 
> I'm not sure if you were following Iranian filtering few days leading to
> the election. It was basically http white-list. Psipohn was sending few 'GET
> / HTTP 1.1' before start sending any real data and it was able to fool
> the box . But the filtering is going to get more intelligent next time,
> and hence I feel stegotorus is more important than ever.

A little birdy whispered in my ear that a much revised version with a
lot of new features and various fixes including a lot of ack/retransmit
fixes should come available soon, but it is pending $org review... that
version even works fine on Windows btw.

> The fundamental thing that is not clear for me is that "If we have the
> assumption that TCP is reliable, this means all packets are going to
> arrive sooner or later. In such situation what's the need for
> re-transmission".

The problem is not about TCP, but more about HTTP where a censor or a
rate-limitter in general (eg Hotel WiFi tends to have issues) does not
always answer every HTTP request and thus one loses packets. Retransmit
is also important in those cases.

Greets,
 Jeroen