Subject: Potential remote listener bug

Potential remote listener bug

From: Przemys³aw Szczygielski <>
Date: Sun, 25 Sep 2011 18:32:02 +0200


I am not sure if it is a libssh2 bug, it might be user side implementation
problem, but then again, you mighty libssh2 wizards know all and probably
will be able to test it.

There's some strange problem with remote listener. Strangely, it occurs In
libssh2 and Putty (i know Putty is not connected to libssh2), it doesn't
occur in Tunnelier or original ssh command. This bug shows up only when
trying to use microsoft RDC.

You may test it like this. Take a client C which is your workplace PC, your
home ssh server S and your home workstation - W. You want to RDC to C from

Client's RDC port 3389 is remotely forwatrded to some port on S (let's
assume 6000), then W connects to S:6000 using microsoft remote desktop
client. The client shows login screen, you enter your user and password,
press enter and... bam! The client disconnects after some seconds (showing
empty desktop for a moment). That is - it disconnects if the port was
forwarded using libssh2 or Putty. As mentioned before Tunnelier and
ssh don't have this problem, the client works as expected - you can work

Now to make it celar - I have a working implementation of "-R" forwarding in
my application, forwarded remote ports work with all other protocols - SSH,
SFTP and even my own file sharing protocol, it's only RDC that causes the
If I am not clear, read this post, that describes exactly the same problem,
with some "me too" responses:
Looks weird, doesn't it?



Received on 2011-09-25