Filtering IP addresses by domain name

[Yasushi Okubo]

Ryan Golhar wrote:

>My machines keep getting attacked through ssh nightly.  I want to
>prevent users from connecting to SSH unless they are coming in through a
>specific ISP.  Is there a way I can filter a range of IPs based on
>provider in iptables?
>
>Ryan
>
>  
>
Is it cost too much/inconvenient for you to setup a dedicated gateway to 
allow remote login from outside/public domain ?
yasushi