These are the port numbers that must be configured on a host-based firewall for a server that needs to allow SSH, FTP, and LDAP traffic. A port number is a numerical identifier that specifies a communication endpoint for a network protocol or an application. A host-based firewall is a software tool that monitors and controls incoming and outgoing network traffic on a single host based on predefined rules. SSH (Secure Shell) is a protocol that allows secure remote access and file transfer over an encrypted connection. The default port number for SSH is 22. FTP (File Transfer Protocol) is a protocol that allows transferring files between hosts over a network connection. The default port number for FTP is 21. LDAP (Lightweight Directory Access Protocol) is a protocol that allows accessing and managing directory services over a network connection. The default port number for LDAP is 389. References: https://www.howtogeek.com/190014/virtualization-basics- understanding-techniques-and-fundamentals/ https://www.howtogeek.com/220152/what-is-the-difference- between-127.0.0.1-and-0.0.0.0/https://www.howtogeek.com/428483/what-is-end-to-end-encryption-and-why- does-it-matter/