OpenSSH server stops returning data from a server module

[Norbert Sendetzky]

Hi all

I've written a client/server application using OpenSSH for securing 
the transactions. The server is written as OpenSSH server module 
(same as sftp) while the client is a seperate application invoking 
the ssh client. My application and the ssh client are connected by 
socketpairs the same way as the OpenSSH server and the server module 
are.

After the connection between the ssh client and the server is 
established, the user is authenticated and the server module is 
loaded, the application starts sending messages to the server module. 
The server module then responds to the former request. After around 
1K of data returned by the server module, the OpenSSH server stops 
forwarding the data returned by the server module, so the failure is 
deterministic.

I've done several tests to exclude a mistake made by myself. The 
server module and the client application seperately work correctly on 
the same data. If I connect the client and the server module directly 
by replacing the execution of the ssh client in the client 
application with the execution of the server module, then there is no 
problem at all.

My tests have shown this behaviour from OpenSSH version 2.9 to 3.1. 
Is there any known problem related to this observation?

TIA


Norbert