I want to allow only machines with allowed ip(s) to login to my system via ssh.For example, userA can use only ip xx.xx.xx.xx or yy.yy.yy.yy to login via ssh, and no other ip can login as the userA. And userB can use only ip zz.zz.zz.zz to login via ssh, no ip other than  zz.zz.zz.zz can login as userB.How should I set up my Linux to achieve this?
How to allow only machines with specified ip to login via ssh?
linux;ssh;networking;permissions;sftp