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SY0-301 · Question #52

A system administrator is using a packet sniffer to troubleshoot remote authentication. The administrator detects a device trying to communicate to TCP port 49. Which of the following authentication…

The correct answer is B. TACACS+. TCP port 49 is the well-known port for TACACS+, making it the authentication protocol most likely in use when traffic to that port is observed.

General security concepts

Question

A system administrator is using a packet sniffer to troubleshoot remote authentication. The administrator detects a device trying to communicate to TCP port 49. Which of the following authentication methods is MOST likely being attempted?

Options

  • ARADIUS
  • BTACACS+
  • CKerberos
  • DLDAP

How the community answered

(52 responses)
  • A
    2% (1)
  • B
    88% (46)
  • C
    4% (2)
  • D
    6% (3)

Why each option

TCP port 49 is the well-known port for TACACS+, making it the authentication protocol most likely in use when traffic to that port is observed.

ARADIUS

RADIUS uses UDP ports 1812 for authentication and 1813 for accounting, not TCP port 49.

BTACACS+Correct

TACACS+ (Terminal Access Controller Access Control System Plus) uses TCP port 49 for all of its authentication, authorization, and accounting communications. TCP provides reliable, connection-oriented transport, which TACACS+ requires to separate its AAA functions into distinct packets.

CKerberos

Kerberos operates on TCP/UDP port 88 for ticket-granting communications, not port 49.

DLDAP

LDAP listens on TCP port 389 (or 636 for LDAPS), not port 49.

Concept tested: TACACS+ default port and protocol

Source: https://www.cisco.com/c/en/us/support/docs/security-vpn/terminal-access-controller-access-control-system-tacacs-/13838-10.html

Topics

#TACACS+#port 49#remote authentication#authentication protocols

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