Examkin

Question

Difficulty: Very hardNetworking Ports and Protocols

A security technician is auditing perimeter firewall rules to enforce encrypted transport standards across the enterprise. The audit reveals that network management agents and directory service clients are communicating using unencrypted protocols over TCP port 389 and UDP port 161. The technician must reconfigure the firewall access control list (ACL) to block these insecure services while permitting their secure, encrypted counterparts for directory queries and network management polling. Which of the following transport protocol and port combinations should be explicitly allowed on the firewall?

  1. TCP port 636 and UDP port 161Answer
  2. B
    TCP port 389 and UDP port 162
  3. C
    UDP port 636 and TCP port 161
  4. D
    TCP port 636 and TCP port 53

Answer

TCP port 636 and UDP port 161 must be allowed.
The combination specifying TCP port 636 and UDP port 161 is correct. LDAPS provides encrypted directory authentication over TCP port 636, replacing cleartext LDAP on TCP port 389. SNMPv3 provides message integrity, authentication, and encryption for network monitoring and continues to use UDP port 161 for polling operations.

Step-by-Step Solution

1
Identify the secure counterpart for unencrypted LDAP (port 389).
Lightweight Directory Access Protocol Secure (LDAPS) encrypts directory queries using SSL/TLS over TCP port 636.
Standard unencrypted LDAP operates on TCP port 389; migrating to LDAPS requires opening TCP port 636.
2
Identify the transport port used for secure network monitoring polling (SNMPv3).
SNMPv3 incorporates authentication and encryption while continuing to use UDP port 161 for standard manager-to-agent polling requests.
SNMP versions 1, 2c, and 3 all utilize UDP port 161 for request/response polling operations, with SNMPv3 adding cryptographic security within the payload.
3
Synthesize the required firewall rule combination.
Permit TCP port 636 for LDAPS and UDP port 161 for SNMPv3 polling.
This combination replaces cleartext LDAP while enabling encrypted directory traffic and secure network monitoring.

Key Concept

Identifying default port numbers and transport layer protocols for secure directory services (LDAPS) and network monitoring (SNMPv3).
Rate this question

Topics

Networking Ports and Protocols

More questions from this topic