I would like to be able to allow connections from all host IP's, but
be able to block connections from any client-versions that we have not
deployed. Is there a way to do this?

For example I've found, that almost all 'crackers' use 'libssh-0.2'
but our users use 'PuTTY-Release-XXXX' so we can freely block

we use:
# ssh -V
OpenSSH_4.7p1-hpn13v1, OpenSSL 0.9.8g 19 Oct 2007
# cat /etc/gentoo-release
Gentoo Base System release

Denis Kot
ICQ: 13680126
Mobil: +375 29 6-1234-78