Do you have a non-US source line?
deb ftp://non-us.debian.org/debian-non-US unstable/non-US main contrib non-free
apt-get install libssl0.9.6 ssh

That should get everything, of course the libssl package may be named
differently in potato.

Andrew S. Zbikowski | http://www.ringworld.org
"We can learn much more from wise words, little
from wisecracks and less from wise guys."
--William Arthur Ward