Which two ports need to be allowed on the firewall for secure access to a remote server?

To secure access to a remote server, allowing TCP port 22 is essential because this port is used by the SSH (Secure Shell) protocol. SSH is a cryptographic network protocol that provides a secure channel over an unsecured network in a client-server architecture. It is widely used for secure remote administration of servers and secure file transfers. By allowing traffic on port 22, you ensure that remote connections to the server are encrypted, which protects sensitive data from being intercepted.

In contrast, the other ports listed serve different purposes that may not provide the same level of security. For example, TCP port 21 is used for FTP (File Transfer Protocol), which transmits data in plaintext and is not secure. TCP port 23 is associated with Telnet, which also transmits data unencrypted. TCP port 25 is typically used for SMTP (Simple Mail Transfer Protocol) for email transmission, and while it has its importance, it does not pertain to secure remote server access. Thus, allowing port 22 is particularly crucial for maintaining secure communications with remote servers.