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Slow connection via Portforward

Mar 19, 2012 at 2:37 PM

Hi, I want to connect to a server application hidden on an open bsd box somewhere in the world. I have managed to get the portforward tunnel working and the connection is fine but seems quite slow to transfer data. I am comparing this to an android app that I have built using the JSch library that seems to perform exactly how I want it to.

Is this normal behaviour and I should accept it or is there a way I can tweek the connection?

The amount of data being transfered is quite small, less than 0.5k on each request, the server is on a slow connection and it does take a little time to establish the initial connection but while this is evident on both platforms the subsequent sluggish data transfer doesn't show on the android app.


Many thanks.




Mar 19, 2012 at 3:56 PM



I constantly trying to improve performance, if I can.

When I checked it last time, it seems that the bottleneck is encryption algorithm.

So improving algorithm performance will defiantly help but I didnt have much luck there.


The only thing I can suggest is to either to use different encryption algorithm or provide your own implementation which could be faster.


May be there is another reason in port forwarding case, since I was doing my code analysis based on SFTP  file transfer but I am not aware of it.




Mar 19, 2012 at 4:48 PM

I'll see if I can do some investigation. For the 1st part I'm only waiting for about 16 bytes to come back from the server, when connecting without ssh (I exposed the port) it seems to be ok. It can't take that long to decrypt 16 bytes, although I know nothing about how that is done!


Cheers for the reply.