Created attachment 1910 [details]
sshd debug and system strace

This was tested on a Suse Linux 11.2

Establishing a port forwarding channel 

ssh -N -R 11001:<clienthost>:443 -o TCPKeepAlive=yes target

and using the channel with 
wget -q --no-check-certificate https://127.0.0.1:11001/

many, many times. 
Every now and then a fd isn't freed again.
In the attachement there is the sshd debug output and
a strace to show that the number of supervised fds in the select call
increase.

The traces are quit big, but not to the bitter end (exhaustion of all fds).