Anderson, a network engineer, installs a firewall and opens ports 80 and 443. He can reach the website, but testing the File Transfer Protocol (FTP) service from the Wide Area Network (WAN) results in access being denied. What MOST LIKELY caused this issue?

Domain 7: Security Operations Practice Questions 
Questions relating to the following topics are included in this domain: 
Understanding and complying with investigations
Proper logging and monitoring activities
Performing configuration management 
Applying fundamental security concepts
Conducting resource protection and incident management