Permit One Service, Not One Host

Scenario

A security review found that the web servers can open any port on the application server, because the rule permitting the two to talk was written by address at a time when only one service was running. The application server now also hosts the database. Restrict the web tier to the application port only, without disturbing the administrators who legitimately need database access.

Learning objectives

• acl
• nftables
• port filtering
• least privilege

Topology and configuration

This environment contains 4 devices (3 Hosts, 1 Router). You configure and troubleshoot the networking skills listed above.

Curriculum topics

• Network Security and Access Control / Filtering by Service

Certification objectives

• ccna-200-301 · Objective 5.6: Configure and verify access control lists
• comptia-network-plus-n10-009 · Objective 4.3: Given a scenario, apply network security features, defense techniques, and solutions