In /etc/ssh

you can create ssh.access and ssh.deny and set user can ssh in server

Note that you should also be able to use PAM. You can also specify what users/group are allowed to do with but writing some "Match group" "Match user" sections. See your man page for sshd_config.

It looks like you can set it in 4 ways in the /etc/ssh/sshd_config file with AllowGroups, AllowUsers, DenyGroups and DenyUsers.

You just seem to use it in that file such as:

AllowGroups sshusers

This link gives a comprehensive overview that even I can understand, so you should have no probs.

http://knowledgelayer.sof ...

I guess an "AllowUser root" or similar would be a good move at the top, just incase it all conflicts. :-)

Yes, I'm pretty sure that it's just AllowGroup isn't it ?