More than one remote port fwd request for the same local port

[Ming-Ching Tiew]

Ming-Ching Tiew wrote:
> Matt Johnston wrote:
>> On Thu, Oct 30, 2008 at 02:37:44PM +0100, Michael Wiedmann wrote:
>>> Hi,
>>> 
>>> how deals dropbear with different clients which are requesting each
>>> a remote port forwarding to the same local port (on the server
>>> side), e.g.
>>> 
>>> system-1> dbclient -l user1 -N -R 7777:client-ip-1:80 server-ip
>>> ...
>>> system-2> dbclient -l user2 -N -R 7777:client-ip-2:80 server-ip
>>> 
>>> Doing a quick test it looks like dropbear accepts the client
>>> requests but the port forwarding does not work (actually it cannot
>>> because there is more than one 'target').
>> 
>> Unix sockets inherently only allow a single process (so a
>> single user) to listen on a port. What behaviour would
>> you expect?
>> 
> 
> I do face the same issue. In my usage, more than one system
> execute the same command ( ie client-ip is actually one only )
> and I don't run any remote shell, the sole purpose of the
> dbclient connection is to establish remote port forward, I
> would prefer the last command succeed and it drops the previous
> connection. However, I do realise  such a behaviour is rather
>  "unfair".
> 

And I did try implement a remote shell method to solve my 
problem, but I was stuck at a stage where I could not identify
the correct dropbear server process  to kill ( ie to kill the 
previous instance of dropbear which started up the 
same port forward ).