Re: ncat is bit slow, corrupts and stops sending data for no reason

[David Fifield <david () bamsoftware com>]

On Wed, Mar 21, 2012 at 06:25:13PM +0200, rndbit wrote:
> Hello,
> I am trying to arrange myself a rdp connection to a firewalled machine.
> Idea is to have a 3rd party server with public ip act as an intermediary
> between rdp client and firewalled computer. It works like this - ncat on
> firewalled computer connects to rdp on 3389 port, then spawns a
> bidirectional connection to a public intermediary server. When ncat on
> public server gets an incoming connection it starts to listen on port
> 7777 for incoming rdp connection. When someone connects - two ncat
> instances join rdp client and firewalled machine via ssl tunnel.
> Something like this:
>
> It sure looks and sounds cool (at least to me), however there is a catch:
>
> Sometimes error pops up when connecting, sometimes i get to windows
> login screen and it pops up after entering credentials and pressing [Ok]
> to log in. RDP is working, but if it did not terminate instantly - it
> would be really awesome. Any idea how could data get corrupted? There
> aint much space for my errors so i guess it must be ncat misbehaving..
> Chasing mice when its not the time for games or something :|
>
> Another thing - if we take --ssl out of equation suddenly it does not
> error, however connection is still rather slow and rdp client just
> freezes before it finishes fully loading desktop. RDP client does not
> notify of disconnect though, it just does not do anything.
>
> I tested both development and stable versions - same. Any clues guys?

What specific versions did you try? This sounds similar to a problem we
had before, that I thought had been fixed:

http://seclists.org/nmap-dev/2010/q3/47

What is the output that you see when you run Ncat with the -vvv option?

David Fifield
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