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Network+ (N10-009) · ELI Explains Port Numbers (book)

Ports Beginners Should Memorize First

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On this page 3 sections
  1. In 30 seconds
  2. The college version
  3. Study tools

In 30 seconds

Use these five sets as a staged study path. Each set contains five ports already explained in the numerical reference.

The college version

Start with web and remote access

  • Port 80: HTTP
  • Port 443: HTTPS and HTTP/3
  • Port 22: SSH and SFTP
  • Port 23: Telnet; insecure remote terminal
  • Port 3389: RDP

Learn core network services

  • Port 53: DNS over UDP and TCP
  • Port 67: DHCP server
  • Port 68: DHCP client
  • Port 123: NTP
  • Port 161: SNMP queries

Add email

  • Port 25: SMTP server-to-server relay
  • Port 110: POP3
  • Port 143: IMAP
  • Port 465: Message submission over implicit TLS
  • Port 587: Message submission, commonly with STARTTLS

Add file sharing and directories

  • Port 20: FTP data in active mode
  • Port 21: FTP control and commands
  • Port 389: LDAP; may use StartTLS
  • Port 445: SMB
  • Port 636: LDAP over implicit TLS

Finish with secure mail and alerts

  • Port 162: SNMP traps
  • Port 993: IMAP over implicit TLS
  • Port 995: POP3 over implicit TLS
  • Port 69: TFTP
  • Port 88: Kerberos authentication

Keep learning

Ready to build on this? Continue to the next lesson.

Practice Network+ (N10-009)

This lesson has no separate scored set. Practice draws from the subject’s question bank.

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