if they are on dynamic ips then you could look up their ip host name and set it as %.etc
like this
My ip : 118.93.**.***
My Ip Hostname : 118-93-**-***.dsl.dyn.ihug.co.nz
remove the ip part and replace with a %
Code:
%.dsl.dyn.ihug.co.nz
that would be for my ips and ip pool ....
you can use this site to look that up
or else take the easy way and set it as % which will allow it from any ip but be very careful with doing this ....