Securing the Firewall in Mac OS X 10.5 "Leopard"

Mac OS X 10.5 includes a built-in firewall to protect your system from intruders, but a few security holes still exist. A third-party application can be used to complement the built-in firewall and further secure your computer from malicious services.

Note: A service refers to a computer program that runs in the background, rather than under the direct control of a user and typically allows external users to connect and exchange information over a network. Some examples of common services include SSH, FTP, and SMTP.

1. Download WaterRoof and install the program to your Applications folder.
2. From the Applications folder, open WaterRoof.
3. At the Welcome admin-account, please enter your password prompt, enter your password for the specified admin-account.
4. From Tools, go to Startup Script, and select Install Startup Script. Click OK at the prompt, and click OK again to confirm the installation.
5. Click Rule Sets to open the Rule Sets settings.
6. If you are not running any services, from the Select Rule set menu, choose Basic configuration.
   
   If you are running services, choose Basic configuration with services, and check the boxes for the services you wish to allow through the firewall.
   
   Note: Make sure that at least one box is checked or WaterRoof will allow any service to access your computer.


7. Make sure flush rules is checked. Click Add Rule Set when finished, and click OK at the confirmation.
   
   Note: If a service or application you are using is not listed by default under the Basic configuration and services rule set, you will need to manually set up a rule by selecting Static Rule from the WaterRoof menu. WaterRoof settings will override the built-in firewall settings.


8. From Tools, select Rules Configuration, and click Save to startup configuration. Click OK to confirm the save.
9. Click Quit to close WaterRoof.
10. From the Apple menu, go to System Preferences, and select Security.
11. Select the Firewall tab and choose Allow all incoming connections. Close the window to save changes.

Enabling Stealth Mode

Once the above steps are completed, you can make your computer appear invisible on the Internet by enabling stealth mode. Stealth mode conceals your computer from common probing techniques used by hackers and others to solicit information about your Internet connection.

1. From the Applications folder, open WaterRoof.
2. Click the Static Rules button.
3. From the Static Rules window, click "+".
4. Fill out the configuration as follows:
   
   Protocol: ICMP
   Rule action: deny
   Source adress, subnet or network: any
   Destination address, subnet or network: any
   Extra arguments: icmptypes 8
   
   Select In and click Add new rule.
   
   
5. From the Static Rules window, verify that the third rule from the bottom, under the rule action category, reads deny icmp from any to any in icmptypes 8.
6. From Tools, select Rules Configuration, and click Save to startup configuration. Click OK to confirm the save.
   

If you make any further changes to the WaterRoof settings, save the changes by going to Tools, selecting Rules Configuration, and clicking Save to startup configuration. This ensures your changes are kept after you reboot your computer.