Limiting SSH Access to Specific IP Addresses

1. Edit /etc/hosts.allow
2. Open a new line before:
   
   # Start by allowing everything (this prevents the rest of the file.
   # from working, so remove it when you need protection).
   # The rules here work on a "First match wins" basis.
   ALL : ALL : allow
   
   and add the following:
   
   sshd: ALL : deny
   
3. For each IP address you want to allow, add the following to /etc/hosts.allow above the line sshd : ALL : deny:
   
   sshd : xxx.xxx.xxx.xxx : allow
   sshd : xxx.xxx.xxx.xxx : allow
   sshd: ALL : deny
4. Save the file

IMPORTANT: Before you log off your current SSH session, try to open another SSH session to the machine you just made these settings on.  If you cannot get into the system, then in your already open SSH session, then comment out the lines you added.