Security Strategies in Linux Platforms and Applications, 3rd Edition

Best Practices: Testing and Reporting

When testing a Linux system, it’s important to test every part of a layered defense. Because some tests may require the temporarily disabling some defenses, it’s appropriate to withdraw a system from production before running some tests. Open ports on a system should appear different inside a firewall from outside a firewall. Tests of TCP Wrapper depend on the rules configured in the /etc/hosts.allow and /etc/hosts.deny files. Tests of some services may be specific to the limitations configured within the configuration files for that service. Tools such as John the Ripper can help identify passwords that are too simple. Be sure to re-enable any disabled services after tests are complete.

Services are not ...