none of these users have static IP addresses 

Ok, then you can not use host based authentication .

Possible solution:

Use AllowUsers in the /etc/ssh/sshd_config

for example

AllowUsers foo@, bar@ 

or even better

AllowUsers [email protected].*, [email protected].*, baz@111.* 

the same for DenyUsers

DenyUsers foo@badhost, [email protected].*, [email protected].* 

none of these users have static IP addresses 

Ok, then you can not use host based authentication .

Possible solution:

Use AllowUsers in the /etc/ssh/sshd_config

for example

AllowUsers foo@, bar@ 

or even better

AllowUsers [email protected].*, [email protected].*, baz@111.* 

the same for DenyUsers

DenyUsers foo@badhost, [email protected].*, [email protected].* 

These allow to configure access for any type of requirement.

none of these users have static IP addresses 

Ok, then you can not use host based authentication .

Possible solution:

Use AllowUsers in the /etc/ssh/sshd_config

for example

AllowUsers foo@, bar@ 

or even better

AllowUsers [email protected].*, [email protected].*, baz@111.* 

none of these users have static IP addresses 

Ok, then you can not use host based authentication .

Possible solution:

Use AllowUsers in the /etc/ssh/sshd_config

for example

AllowUsers foo@, bar@ 

or even better

AllowUsers [email protected].*, [email protected].*, baz@111.* 

the same for DenyUsers

DenyUsers foo@badhost, [email protected].*, [email protected].*