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Difficulty: HardCommon Ports and Protocols

A network administrator is establishing stateful firewall rules to allow remote administrative workstations to securely manage internal Linux servers via encrypted command-line sessions and authenticate against a directory server using SSL/TLS encryption. Unencrypted management traffic must remain strictly blocked. Which TWO port and transport protocol combinations must be explicitly permitted to support these administrative requirements? (Select TWO.)

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

Answer

TCP port 22 (for SSH) and TCP port 636 (for LDAPS) must be explicitly permitted.
Encrypted remote terminal access is provided by SSH over TCP port 22. Encrypted directory services authentication is provided by LDAPS over TCP port 636. Both protocols require connection-oriented TCP transport to establish stateful, reliable cryptographic sessions.

Step-by-Step Solution

1
Identify the protocol required for secure remote command-line administration.
Secure Shell (SSH) is required, which operates on standard TCP port 22.
SSH replaces unencrypted Telnet (TCP 23) to satisfy secure remote administration policies.
2
Identify the protocol required for encrypted directory service queries.
Lightweight Directory Access Protocol over SSL/TLS (LDAPS) is required, which operates on standard TCP port 636.
LDAPS encrypts directory authentication traffic, whereas unencrypted LDAP uses TCP port 389.
3
Verify the correct Transport Layer protocol for both services.
Both SSH and LDAPS rely on TCP for connection reliability and TLS/session handling.
UDP is connectionless and cannot support the reliable handshakes required by SSH and TLS encryption streams.

Key Concept

Standard service port numbers and transport protocol selection for secure remote access and directory services
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Topics

Common Ports and Protocols

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