Security-Related Ports: LDAP, Kerberos, RADIUS, and More

Security and Authentication Ports

Security infrastructure relies on specific ports for authentication, authorization, and monitoring.

Directory and Authentication Services

Port	Service	Encryption
88	Kerberos	Native encryption
389	LDAP	None (STARTTLS available)
636	LDAPS	Implicit TLS
464	Kerberos Password Change	Native encryption
1812	RADIUS Authentication	Shared secret
1813	RADIUS Accounting	Shared secret

Kerberos (Port 88)

Kerberos is the primary authentication protocol for:

• Active Directory environments
• Linux/Unix single sign-on (SSO)
• Hadoop cluster security

It uses a ticket-based system where clients obtain tickets from a Key Distribution Center (KDC) to access services without transmitting passwords.

LDAP / LDAPS (Ports 389 / 636)

LDAP is the standard protocol for directory services:

• Port 389: Unencrypted LDAP (supports STARTTLS upgrade)
• Port 636: LDAP over implicit TLS

Always use LDAPS (636) or LDAP with STARTTLS (389) in production to encrypt directory queries that may contain sensitive user information.

Monitoring and Logging

Port	Service	Protocol
161	SNMP	UDP
162	SNMP Trap	UDP
514	Syslog	UDP

SNMP (Simple Network Management Protocol) is used to monitor network devices. Use SNMPv3 for encrypted monitoring. Syslog sends log messages to a centralized server. Consider using rsyslog with TLS for encrypted log transport.