Security+ SY0-701 Study Guide

Essential Port Numbers Reference

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About Port Numbers

Port numbers are used to identify specific processes or services running on a computer. Understanding common port numbers is essential for network security, firewall configuration, and troubleshooting.

  • Well-known ports: 0-1023 (system processes)
  • Registered ports: 1024-49151 (user processes)
  • Dynamic/private ports: 49152-65535 (ephemeral ports)
Common Services
Port 20/21
FTP (File Transfer Protocol)
File transfer protocol. Port 20 for data, 21 for control.
TCP
Port 22
SSH (Secure Shell)
Secure remote administration and file transfer.
TCP
Port 23
Telnet
Unencrypted remote administration (insecure).
TCP
Port 25
SMTP (Simple Mail Transfer Protocol)
Email transmission between mail servers.
TCP
Port 53
DNS (Domain Name System)
Domain name to IP address resolution.
TCP/UDP
Port 80
HTTP (Hypertext Transfer Protocol)
Web traffic (unencrypted).
TCP
Port 110
POP3 (Post Office Protocol v3)
Email retrieval from server to client.
TCP
Port 143
IMAP (Internet Message Access Protocol)
Email management on server.
TCP
Secure Services
Port 443
HTTPS (HTTP Secure)
Encrypted web traffic using SSL/TLS.
TCP
Port 993
IMAPS (IMAP Secure)
Secure version of IMAP.
TCP
Port 995
POP3S (POP3 Secure)
Secure version of POP3.
TCP
Port 22
SFTP (SSH File Transfer Protocol)
Secure file transfer over SSH.
TCP
Port 989/990
FTPS (FTP Secure)
FTP over SSL/TLS.
TCP
Remote Access
Port 3389
RDP (Remote Desktop Protocol)
Windows remote desktop access.
TCP
Port 5900
VNC (Virtual Network Computing)
Cross-platform remote desktop.
TCP
Port 1723
PPTP (Point-to-Point Tunneling Protocol)
VPN protocol (less secure).
TCP
Network Services
Port 67/68
DHCP (Dynamic Host Configuration Protocol)
Automatic IP address assignment.
UDP
Port 69
TFTP (Trivial File Transfer Protocol)
Simple file transfer without authentication.
UDP
Port 161/162
SNMP (Simple Network Management Protocol)
Network device monitoring and management.
UDP
Port 389
LDAP (Lightweight Directory Access Protocol)
Directory services access.
TCP/UDP
Port 636
LDAPS (LDAP Secure)
Secure LDAP over SSL.
TCP
Security & Management
Port 514
Syslog
System logging service.
UDP
Port 1812/1813
RADIUS (Remote Authentication Dial-In User Service)
Network access authentication and accounting.
UDP
Port 1645/1646
RADIUS (legacy)
Older RADIUS ports.
UDP
Port 1701
L2TP (Layer 2 Tunneling Protocol)
VPN protocol often used with IPsec.
UDP
Port 1720
H.323
VoIP and videoconferencing protocol.
TCP
Database Services
Port 1433
Microsoft SQL Server
Default SQL Server database port.
TCP
Port 1521
Oracle Database
Default Oracle database port.
TCP
Port 3306
MySQL
Default MySQL database port.
TCP
Port 5432
PostgreSQL
Default PostgreSQL database port.
TCP

Exam Tips

  • Memorize ports for common services (HTTP, HTTPS, SSH, DNS, etc.)
  • Understand which protocols use TCP vs UDP
  • Know secure vs insecure versions of protocols (HTTP vs HTTPS)
  • Remember port ranges: well-known (0-1023), registered (1024-49151), dynamic (49152-65535)
  • Focus on ports mentioned in Security+ exam objectives