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Difficulty: Very hardCommon Ports and Protocols

A network administrator is configuring stateless inbound and outbound access control lists (ACLs) on an enterprise edge firewall connecting a remote branch to the corporate datacenter. Corporate security policy mandates that all administrative remote access and directory authentication services must be fully encrypted in transit, strictly prohibiting cleartext credentials or unencrypted management protocols. During post-deployment testing, packet captures show that administrative CLI management sessions and secure directory queries are being dropped by the firewall. Which of the following transport layer protocol and destination port combinations MUST be explicitly allowed in the firewall rules to restore these required secure services? (Select TWO.)

  1. TCP port 22Answer
  2. TCP port 636Answer
  3. C
    UDP port 22
  4. D
    TCP port 389

Answer

The firewall must permit TCP port 22 for secure SSH terminal access and TCP port 636 for encrypted LDAPS directory service authentication.
The correct answers represent the standard transport protocol and port assignments for secure administrative access and encrypted directory services. Secure Shell (SSH) uses TCP port 22 to establish encrypted terminal sessions. Lightweight Directory Access Protocol Secure (LDAPS) uses TCP port 636 to encapsulate directory service communication within an SSL/TLS tunnel, fulfilling the corporate requirement for encrypted transit.

Step-by-Step Solution

1
Identify the protocol requirements from the scenario constraints.
The scenario requires encrypted remote CLI management and encrypted directory service authentication.
Security policy explicitly forbids cleartext protocols such as Telnet or standard LDAP.
2
Determine the transport protocol and default port number for secure remote CLI management.
SSH (Secure Shell) provides encrypted CLI administration over TCP port 22.
SSH requires connection-oriented TCP to maintain reliable session control and stream encryption.
3
Determine the transport protocol and default port number for encrypted directory authentication.
LDAPS (LDAP over TLS/SSL) operates over TCP port 636.
Standard LDAP over TCP port 389 sends credentials in cleartext; TLS wrapper on port 636 encrypts the entire LDAP session payload.

Key Concept

Identification of default port numbers and transport layer choices for secure management and directory protocols (SSH on TCP 22 vs LDAPS on TCP 636).
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Topics

Common Ports and Protocols

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