I have followed the steps here http://www.macsat.com/macsat/content/view/37/30/ to install openssh-sftp-server.
Everything went fine but it didn't work, when the protocol is set to SFTP the error in winscp is:

Cannot initalize SFTP protocol. Is the host running a SFTP server?
Connection has been unexpectedly closed. Server sent command exit status 127

logread -f shows:

Sep  7 15:41:24 (none) kern.info dropbear[987]: Child connection from x.x.x.x:60555
Sep  7 15:41:25 (none) kern.notice dropbear[987]: password auth succeeded for 'root' from x.x.x.x:60555
Sep  7 15:41:25 (none) kern.info dropbear[987]: exit after auth (root): received data with bad writefd

or

Sep  7 15:40:32 (none) kern.info dropbear[981]: Child connection from x.x.x.x:60537
Sep  7 15:40:33 (none) kern.notice dropbear[981]: password auth succeeded for 'root' from x.x.x.x:60537
Sep  7 15:40:33 (none) kern.info dropbear[981]: exit after auth (root): Exited normally

When setting the protocol to scp, I can log in after displaying some errors. Any idea?

Thanks

WL500gp

Ok solved this already. The reason was that libopenssl, zlib packages were installed to /opt (usb). I had to add few synlinks:
ln -s /opt/usr/lib/libcrypto.so.0.9.7 /usr/lib/libcrypto.so.0.9.7
ln -s /opt/usr/lib/libz.so.1 /usr/lib/libz.so.1

I have followed this nice guide http://www.macsat.com/macsat/content/view/16/30/ and added export LD_LIBRARY_PATH=/lib:/usr/lib:/opt/usr/lib:/opt/lib to /etc/profile and rebooted to avoide this problem but didn't help.

Anything wrong?

Commands in /etc/profile are executed when you login, so if you login and start a program which needs a library in /opt/usr/lib it will work.
But the sftp-server is started by dropbear which in turn was started by one of the init scripts, which simply don't know of or care about /etc/profile.

ok, it's clear, why it doesn't work. But I'm looking for a solution, I don't have to solve for each package. What I'm looking for is a possibility to set path as well as ld_library_path at boot-time and therefore for all processes. That sounds total easy, but I haven't found a solution.

if that doesn't work with a symlink from /opt , that is because /opt is not mounted before sftp server sarted...

so mount your /opt before