I want to allow only machines with allowed ip(s) to login to my system via ssh.
userA can use only ip
yy.yy.yy.yy to login via ssh, and no other ip can login as the
userB can use only ip
zz.zz.zz.zz to login via ssh, no ip other than
zz.zz.zz.zz can login as
How should I set up my Linux to achieve this?