Information Security Commons^™

Understanding Firewalld In Multi-Zone Configurations, Nathan R. Vance, William F. Polik

Faculty Publications

Stories of compromised servers and data theft fill today's news. It isn't difficult for someone who has read an informative blog post to access a system via a misconfigured service, take advantage of a recently exposed vulnerability, or gain control using a stolen password. Any of the many internet services found on a typical Linux server could harbor a vulnerability that grants unauthorized access to the system.

Since it's an impossible task to harden a system at the application level against every possible threat, firewalls provide security by limiting access to a system. Firewalls filter incoming packets based on their …