Add user to SSH group safe?
Solution 1:
The purpose of ssh group was described on Unix. There is no gain by adding user to ssh group, because the group is used only for pre-authentication process.
If you want to use a group to limit who can log in to your server using ssh, create a group sshuser, add AllowGroups sshuser to your /etc/ssh/sshd_config and restart your ssh service.