In addition to turning off root access by putting the following line in my 
/etc/sshd_config file...

PermitRootLogin no

...I also use tcp wrappers to deny access to people in Europe, South 
America and Asia and one annoying domain in Canada.  Here are the lines 
for /etc/hosts.deny

# I used to block ssh from everywhere, now I only block foreign countries
# see this web page:  http://www.iana.org/assignments/ipv4-address-space
sshd sshd2 sshdfwd-X11: 43. 61. 62. 80. 81. 193. 194. 195. 200. 201. 202. 203. 210. 211. 212. 213. 217. 218. 219. 220. .sympatico.ca

You must compile sshd to use tcp wrappers, I think by compiling against 
libwrap.a .  I also recommend this for VNC users.

Sorry that I won't be able to answer questions about this, if there are 
any, but I think there must be info on the 'net.

Mike

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